Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-09-20 06:53:04 +00:00
Code Issues Packages Projects Releases Wiki Activity
1,303,990 Commits 7 Branches 853 Tags 5.7 GiB
master
Commit Graph

2564 Commits

Author SHA1 Message Date
Linus Torvalds
2004cef11e In the v6.12 scheduler development cycle we had 63 commits from 18 contributors: 
- Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot de Oliveira's
    last major contribution to the kernel:
 
      "SCHED_DEADLINE servers can help fixing starvation issues of low priority
      tasks (e.g., SCHED_OTHER) when higher priority tasks monopolize CPU
      cycles. Today we have RT Throttling; DEADLINE servers should be able to
      replace and improve that."
 
      (Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes,
       Youssef Esmat, Huang Shijie)
 
  - Preparatory changes for sched_ext integration:
 
      - Use set_next_task(.first) where required
      - Fix up set_next_task() implementations
      - Clean up DL server vs. core sched
      - Split up put_prev_task_balance()
      - Rework pick_next_task()
      - Combine the last put_prev_task() and the first set_next_task()
      - Rework dl_server
      - Add put_prev_task(.next)
 
       (Peter Zijlstra, with a fix by Tejun Heo)
 
  - Complete the EEVDF transition and refine EEVDF scheduling:
 
      - Implement delayed dequeue
      - Allow shorter slices to wakeup-preempt
      - Use sched_attr::sched_runtime to set request/slice suggestion
      - Document the new feature flags
      - Remove unused and duplicate-functionality fields
      - Simplify & unify pick_next_task_fair()
      - Misc debuggability enhancements
 
       (Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann,
        Valentin Schneider and Chuyi Zhou)
 
  - Initialize the vruntime of a new task when it is first enqueued,
    resulting in significant decrease in latency of newly woken tasks.
    (Zhang Qiao)
 
  - Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
    (K Prateek Nayak, Peter Zijlstra)
 
  - Clean up and clarify the usage of Clean up usage of rt_task()
    (Qais Yousef)
 
  - Preempt SCHED_IDLE entities in strict cgroup hierarchies
    (Tianchen Ding)
 
  - Clarify the documentation of time units for deadline scheduler
    parameters. (Christian Loehle)
 
  - Remove the HZ_BW chicken-bit feature flag introduced a year ago,
    the original change seems to be working fine.
    (Phil Auld)
 
  - Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
    Peilin He, Qais Yousefm and Vincent Guittot)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmbr8qcRHG1pbmdvQGtl
 cm5lbC5vcmcACgkQEnMQ0APhK1gdbw/+Mj3zWfYP+dtUkfgrR2FClPAJoo1/9Dz0
 LYD8XgYHu8rEJ0Aq+VbdkgYGUt9utvzUFPIxvWFDcldQl57KwhF4hp9Ir+PqJyYC
 NolQ1q8ddo1hnslxnEg6SgHVzQq/4FqMM0nDNUkQETCx6zTyFFeRf+q7o/2c2m5B
 uI9dSU1Wrx7XrXm2D3kB8+xP+ZRy+qhbFN5Pfuz96mhelfklylgKMfPzgAiCT/7T
 JTbQhQ2HdcCNgiLoSrWsHBDy2UYpouP4zb4jyd+lDQzhSUJrj3u4Xy4vVmuTKq+y
 sTgWlgKB+MTuh9UuJ4UYzSnMqg161UlMvtXeH84ABmAqDNGHRPtOKrrlcLtJ3D4x
 m1SPhNnsvpjOu2pH0XLIS8al3VUesWND5S+rucHRYSq6Nvhivf4MTvRJlicXXurL
 Mt2APnIlhGJuKBNWnmyZovVdtO0ZUUPlaZWfr3rCS4txAVo+HwWhsm3uhtTycQqN
 gazsCiuGh6Jds90ZqA/BvdLWG+DY8J0xLlV3ex4pCXuQ/HFrabVWTyThJsULhrZ2
 5mTdWIsocPctNMO9/RHMy7vJI7G7ljgHEquWVn5kiGGzXhK6VwVwKAMpfgXGw+YA
 yVP6/M7a7g2yEzj69gXkcDa8k/kedMVquJ/G/8YhZM7u7sPqsMjpmaGsqsJRfnpT
 ChngAzap+kA=
 =TEC6
 -----END PGP SIGNATURE-----

Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot
   de Oliveira's last major contribution to the kernel:

     "SCHED_DEADLINE servers can help fixing starvation issues of low
      priority tasks (e.g., SCHED_OTHER) when higher priority tasks
      monopolize CPU cycles. Today we have RT Throttling; DEADLINE
      servers should be able to replace and improve that."

   (Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes, Youssef
   Esmat, Huang Shijie)

 - Preparatory changes for sched_ext integration:
     - Use set_next_task(.first) where required
     - Fix up set_next_task() implementations
     - Clean up DL server vs. core sched
     - Split up put_prev_task_balance()
     - Rework pick_next_task()
     - Combine the last put_prev_task() and the first set_next_task()
     - Rework dl_server
     - Add put_prev_task(.next)

   (Peter Zijlstra, with a fix by Tejun Heo)

 - Complete the EEVDF transition and refine EEVDF scheduling:
     - Implement delayed dequeue
     - Allow shorter slices to wakeup-preempt
     - Use sched_attr::sched_runtime to set request/slice suggestion
     - Document the new feature flags
     - Remove unused and duplicate-functionality fields
     - Simplify & unify pick_next_task_fair()
     - Misc debuggability enhancements

   (Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann, Valentin
   Schneider and Chuyi Zhou)

 - Initialize the vruntime of a new task when it is first enqueued,
   resulting in significant decrease in latency of newly woken tasks
   (Zhang Qiao)

 - Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
   (K Prateek Nayak, Peter Zijlstra)

 - Clean up and clarify the usage of Clean up usage of rt_task()
   (Qais Yousef)

 - Preempt SCHED_IDLE entities in strict cgroup hierarchies
   (Tianchen Ding)

 - Clarify the documentation of time units for deadline scheduler
   parameters (Christian Loehle)

 - Remove the HZ_BW chicken-bit feature flag introduced a year ago,
   the original change seems to be working fine (Phil Auld)

 - Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
   Peilin He, Qais Yousefm and Vincent Guittot)

* tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
  sched/cpufreq: Use NSEC_PER_MSEC for deadline task
  cpufreq/cppc: Use NSEC_PER_MSEC for deadline task
  sched/deadline: Clarify nanoseconds in uapi
  sched/deadline: Convert schedtool example to chrt
  sched/debug: Fix the runnable tasks output
  sched: Fix sched_delayed vs sched_core
  kernel/sched: Fix util_est accounting for DELAY_DEQUEUE
  kthread: Fix task state in kthread worker if being frozen
  sched/pelt: Use rq_clock_task() for hw_pressure
  sched/fair: Move effective_cpu_util() and effective_cpu_util() in fair.c
  sched/core: Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
  sched: Add put_prev_task(.next)
  sched: Rework dl_server
  sched: Combine the last put_prev_task() and the first set_next_task()
  sched: Rework pick_next_task()
  sched: Split up put_prev_task_balance()
  sched: Clean up DL server vs core sched
  sched: Fixup set_next_task() implementations
  sched: Use set_next_task(.first) where required
  sched/fair: Properly deactivate sched_delayed task upon class change
  ...
 2024-09-19 15:55:58 +02:00
Linus Torvalds
4a39ac5b7d Random number generator updates for Linux 6.12-rc1. 
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEq5lC5tSkz8NBJiCnSfxwEqXeA64FAmboHyUACgkQSfxwEqXe
 A66wGQ/8DRIjBllwf1YuTWi4T6OcfoYxK6C9bXO6QPP5gzdTyFE9pvDuuPyad6+F
 FR086ydTHeodemz1dFiQCL9etcUaxo4+6FRKyXKF9/1ezGbTA5nJd0/fKJGlqbI2
 EoA4LNYHOsvCZk1BTpxRNWKeKphU9zQgQdSigy6Rx8p269UkGmIZjD1PtUc+vqfR
 Ox0dK/Cswyo236fRi5HzaoMntWI4vXgLfxty0e1R7tfbstkCxSKWAON1lo3uHgkA
 0HpJXWgWXAPt9gp++Fs/jGNpOqbt6IaKeV5f7CjYfvWhlFjNMhQxF+PbxknaZn/k
 K0gQsItOIoFTfbQdLDIdfnj9awMdLW8FB2A1WXHpNr9pVC4ickPb1bMTF/XRd0tm
 wBNu4BL0gklx6017KZg5uINMIduzMLGkBLRFiBW0en/sZMLTJTMg58BJn0CL1Pmh
 1ll/Q3ToSMHalvxU2OnJagTwh4fzzCEpK/hW9WiDO4jSCsMXyX0clinrCjNo1JfA
 tqgTWEy3uGtg+dg0Du9VD5JASbNQSJ0ZRnas5+qz10IRWWfTolrsk61dliXLQ4Sv
 tSryDtsE2znwJF1Krh4aHNSSVhD5/l/8QaXkf9aZc/kkaHxwsx83FuWnqw6nMz8c
 l4B2MbH0jUgsEqEyx+0iwk+FXE9kZKWumTVLjFZ6bRnq3q+uq0U=
 =mWCw
 -----END PGP SIGNATURE-----

Merge tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:
 "Originally I'd planned on sending each of the vDSO getrandom()
  architecture ports to their respective arch trees. But as we started
  to work on this, we found lots of interesting issues in the shared
  code and infrastructure, the fixes for which the various archs needed
  to base their work.

  So in the end, this turned into a nice collaborative effort fixing up
  issues and porting to 5 new architectures -- arm64, powerpc64,
  powerpc32, s390x, and loongarch64 -- with everybody pitching in and
  commenting on each other's code. It was a fun development cycle.

  This contains:

   - Numerous fixups to the vDSO selftest infrastructure, getting it
     running successfully on more platforms, and fixing bugs in it.

   - Additions to the vDSO getrandom & chacha selftests. Basically every
     time manual review unearthed a bug in a revision of an arch patch,
     or an ambiguity, the tests were augmented.

     By the time the last arch was submitted for review, s390x, v1 of
     the series was essentially fine right out of the gate.

   - Fixes to the the generic C implementation of vDSO getrandom, to
     build and run successfully on all archs, decoupling it from
     assumptions we had (unintentionally) made on x86_64 that didn't
     carry through to the other architectures.

   - Port of vDSO getrandom to LoongArch64, from Xi Ruoyao and acked by
     Huacai Chen.

   - Port of vDSO getrandom to ARM64, from Adhemerval Zanella and acked
     by Will Deacon.

   - Port of vDSO getrandom to PowerPC, in both 32-bit and 64-bit
     varieties, from Christophe Leroy and acked by Michael Ellerman.

   - Port of vDSO getrandom to S390X from Heiko Carstens, the arch
     maintainer.

  While it'd be natural for there to be things to fix up over the course
  of the development cycle, these patches got a decent amount of review
  from a fairly diverse crew of folks on the mailing lists, and, for the
  most part, they've been cooking in linux-next, which has been helpful
  for ironing out build issues.

  In terms of architectures, I think that mostly takes care of the
  important 64-bit archs with hardware still being produced and running
  production loads in settings where vDSO getrandom is likely to help.

  Arguably there's still RISC-V left, and we'll see for 6.13 whether
  they find it useful and submit a port"

* tag 'random-6.12-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (47 commits)
  selftests: vDSO: check cpu caps before running chacha test
  s390/vdso: Wire up getrandom() vdso implementation
  s390/vdso: Move vdso symbol handling to separate header file
  s390/vdso: Allow alternatives in vdso code
  s390/module: Provide find_section() helper
  s390/facility: Let test_facility() generate static branch if possible
  s390/alternatives: Remove ALT_FACILITY_EARLY
  s390/facility: Disable compile time optimization for decompressor code
  selftests: vDSO: fix vdso_config for s390
  selftests: vDSO: fix ELF hash table entry size for s390x
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO64
  powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32
  powerpc/vdso: Refactor CFLAGS for CVDSO build
  powerpc/vdso32: Add crtsavres
  mm: Define VM_DROPPABLE for powerpc/32
  powerpc/vdso: Fix VDSO data access when running in a non-root time namespace
  selftests: vDSO: don't include generated headers for chacha test
  arm64: vDSO: Wire up getrandom() vDSO implementation
  arm64: alternative: make alternative_has_cap_likely() VDSO compatible
  selftests: vDSO: also test counter in vdso_test_chacha
  ...
 2024-09-18 15:26:31 +02:00
Linus Torvalds
c903327d32 printk changes for 6.12 
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEESH4wyp42V4tXvYsjUqAMR0iAlPIFAmbi598ACgkQUqAMR0iA
 lPL3lw//WaRDKJ1Cb/bKAn3nRpjdqiNBI//K1gRJp0LgLE7qEudE25t4j3F9tvvP
 pc9AB81g1Au8Br6iOd+NiGXXW5KWJHaZ3rUAdeo6co4NQCbrY6qTA78ItZSQImBH
 A9fhWWr1TGRX8L/N/gR2eYBnpbDGIbRahUOQraUpBn4kEPyR47KEx7Njjo48GcmR
 Ye8dIYwUOWEgQeIuIxIAwNf6KyNjo5tQpgve+M8HGwy8mZqP9XV6UjXUACVwQNx6
 +CK+IGM+94tCq5KalOaJ5BtsXGKlabHIs7y9QpLS45M2QoHIlDIvpaxzLf0FTsPI
 CppqedAGN2jU0NyjfbFk1c+SNQfDZEAZVyF6vKFelP7t2jzAx301RyB2S+Cm7Hh+
 PajFty41UT0/y17V4sZawfMqpFyp7Wr6RKQYYKMBRdSQQkToh/dmebBvqPAHW9cJ
 LInQQf+XdzbonKa+CTmT/Tg+eM2R124FWeMVnEMdtyXpKUV9qdKWfngtzyRMQiYI
 q54ZwKd3VJ9kRIfb7Fp0TBr2NErdnEQE5hh9QhI8SAWENskw5+GmYaQit734U9wA
 SU7t9rir7NS4Rc1jHP9SQ9oWWI9HT4hthRGkLh2Knx0O2c6AwOuEI4wkjzSWI3GX
 /eeofnbZiUpi7fESf9qmTGtQZ4/9ogQ7fNaroWCSfQzq3+wl+2o=
 =28sV
 -----END PGP SIGNATURE-----

Merge tag 'printk-for-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:
 "This is the "last" part of the support for the new nbcon consoles.
  Where "nbcon" stays for "No Big console lock CONsoles" aka not under
  the console_lock.

  New callbacks are added to struct console:

   - write_thread() for flushing nbcon consoles in task context.

   - write_atomic() for flushing nbcon consoles in atomic context,
     including NMI.

   - con->device_lock() and device_unlock() for taking the driver
     specific lock, for example, port->lock.

  New printk-specific kthreads are created:

   - per-console kthreads which get responsible for flushing normal
     priority messages on nbcon consoles.

   - thread which gets responsible for flushing normal priority messages
     on all consoles when CONFIG_RT enabled.

  The new callbacks are called under a special per-console lock which
  has already been added back in v6.7. It allows to distinguish three
  severities: normal, emergency, and panic. A context with a higher
  priority could take over the ownership when it is safe even in the
  middle of handling a record. The panic context could do it even when
  it is not safe. But it is allowed only for the final desperate flush
  before entering the infinite loop.

  The new lock helps to flush the messages directly in emergency and
  panic contexts. But it is not enough in all situations:

   - console_lock() is still need for synchronization against boot
     consoles.

   - con->device_lock() is need for synchronization against other
     operations on the same HW, e.g. serial port speed setting,
     non-printk related read/write.

  The dependency on con->device_lock() is mutual. Any code taking the
  driver specific lock has to acquire the related nbcon console context
  as well. For example, see the new uart_port_lock() API. It provides
  the necessary synchronization against emergency and panic contexts
  where the messages are flushed only under the new per-console lock.

  Maybe surprisingly, a quite tricky part is the decision how to flush
  the consoles in various situations. It has to take into account:

   - message priority:    normal, emergency, panic

   - scheduling context:  task, atomic, deferred_legacy

   - registered consoles: boot, legacy, nbcon

   - threads are running: early boot, suspend, shutdown, panic

   - caller:              printk(), pr_flush(), printk_flush_in_panic(),
                          console_unlock(), console_start(), ...

  The primary decision is made in printk_get_console_flush_type(). It
  creates a hint what the caller should do:

   - flush nbcon consoles directly or via the kthread

   - call the legacy loop (console_unlock()) directly or via irq_work

  The existing behavior is preserved for the legacy consoles. The only
  exception is that they are not longer flushed directly from printk()
  in panic() before CPUs are stopped. But this blocking happens only
  when at least one nbcon console is registered. The motivation is to
  increase a chance to produce the crash dump. They legacy consoles
  might create a deadlock in compare with nbcon consoles. The nbcon
  console should allow to see the messages even when the crash dump
  fails.

  There are three possible ways how nbcon consoles are flushed:

   - The per-nbcon-console kthread is responsible for flushing messages
     added with the normal priority. This is the default mode.

   - The legacy loop, aka console_unlock(), is used when there is still
     a boot console registered. There is no easy way how to match an
     early console driver with a nbcon console driver. And the
     console_lock() provides the only reliable serialization at the
     moment.

     The legacy loop uses either con->write_atomic() or
     con->write_thread() callbacks depending on whether it is allowed to
     schedule. The atomic variant has to be used from printk().

   - In other situations, the messages are flushed directly using
     write_atomic() which can be called in any context, including NMI.
     It is primary needed during early boot or shutdown, in emergency
     situations, and panic.

  The emergency priority is used by a code called within
  nbcon_cpu_emergency_enter()/exit(). At the moment, it is used in four
  situations: WARN(), Oops, lockdep, and RCU stall reports.

  Finally, there is no nbcon console at the moment. It means that the
  changes should _not_ modify the existing behavior. The only exception
  is CONFIG_RT which would force offloading the legacy loop, for normal
  priority context, into the dedicated kthread"

* tag 'printk-for-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (54 commits)
  printk: Avoid false positive lockdep report for legacy printing
  printk: nbcon: Assign nice -20 for printing threads
  printk: Implement legacy printer kthread for PREEMPT_RT
  tty: sysfs: Add nbcon support for 'active'
  proc: Add nbcon support for /proc/consoles
  proc: consoles: Add notation to c_start/c_stop
  printk: nbcon: Show replay message on takeover
  printk: Provide helper for message prepending
  printk: nbcon: Rely on kthreads for normal operation
  printk: nbcon: Use thread callback if in task context for legacy
  printk: nbcon: Relocate nbcon_atomic_emit_one()
  printk: nbcon: Introduce printer kthreads
  printk: nbcon: Init @nbcon_seq to highest possible
  printk: nbcon: Add context to usable() and emit()
  printk: Flush console on unregister_console()
  printk: Fail pr_flush() if before SYSTEM_SCHEDULING
  printk: nbcon: Add function for printers to reacquire ownership
  printk: nbcon: Use raw_cpu_ptr() instead of open coding
  printk: Use the BITS_PER_LONG macro
  lockdep: Mark emergency sections in lockdep splats
  ...
 2024-09-17 08:52:28 +02:00
Linus Torvalds
9ea925c806 Updates for timers and timekeeping: 
- Core:
 
 	- Overhaul of posix-timers in preparation of removing the
 	  workaround for periodic timers which have signal delivery
 	  ignored.
 
         - Remove the historical extra jiffie in msleep()
 
 	  msleep() adds an extra jiffie to the timeout value to ensure
 	  minimal sleep time. The timer wheel ensures minimal sleep
 	  time since the large rewrite to a non-cascading wheel, but the
 	  extra jiffie in msleep() remained unnoticed. Remove it.
 
         - Make the timer slack handling correct for realtime tasks.
 
 	  The procfs interface is inconsistent and does neither reflect
 	  reality nor conforms to the man page. Show the correct 0 slack
 	  for real time tasks and enforce it at the core level instead of
 	  having inconsistent individual checks in various timer setup
 	  functions.
 
         - The usual set of updates and enhancements all over the place.
 
   - Drivers:
 
         - Allow the ACPI PM timer to be turned off during suspend
 
 	- No new drivers
 
 	- The usual updates and enhancements in various drivers
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmbn7jQTHHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYobqnD/9COlU0nwsulABI/aNIrsh6iYvnCC9v
 14CcNta7Qn+157Wfw9BWOyHdNhR1/fPCXE8jJ71zTyIOeW27HV2JyTtxTwe9ZcdK
 ViHAaj7YcIjcVUEC3StCoRCPnvLslEw4qJA5AOQuDyMivdQn+YVa2c0baJxKaXZt
 xk4HZdMj4NAS0jRKnoZSwtKW/+Oz6rR4GAWrZo+Zs1/8ur3HfqnQfi8lJ1hJtLLW
 V7XDCVRvamVi6Ah3ocYPPp/1P6yeQDA1ge9aMddqaza5STWISXRtSnFMUmYP3rbS
 FaL8TyL+ilfny8pkGB2WlG6nLuSbtvogtdEh1gG1k1RmZt44kAtk8ba/KiWFPBSb
 zK9cjojRMBS71f9G4kmb5F4rnXoLsg1YbD1Nzhz3wq2Cs1Z90dc2QwMren0zoQ1x
 Fn56ueRyAiagBlnrSaKyso/2RvqJTNoSdi3RkpjYeAph0UoDCqvTvKjGAf1mWiw1
 T/1lUWSVqWHnzZbM7XXzzajIN9bl6A7bbqlcAJ2O9vZIDt7273DG+bQym9Vh6Why
 0LTGGERHxzKBsG7WRg+2Gmvv6S18UPKRo8tLtlA758rHlFuPTZCShWrIriwSNl1K
 Hxon+d4BparSnm1h9W/NHPKJA574UbWRCBjdk58IkAj8DxZZY4ORD9SMP+ggkV7G
 F6p9cgoDNP9KFg==
 =jE0N
 -----END PGP SIGNATURE-----

Merge tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Core:

   - Overhaul of posix-timers in preparation of removing the workaround
     for periodic timers which have signal delivery ignored.

   - Remove the historical extra jiffie in msleep()

     msleep() adds an extra jiffie to the timeout value to ensure
     minimal sleep time. The timer wheel ensures minimal sleep time
     since the large rewrite to a non-cascading wheel, but the extra
     jiffie in msleep() remained unnoticed. Remove it.

   - Make the timer slack handling correct for realtime tasks.

     The procfs interface is inconsistent and does neither reflect
     reality nor conforms to the man page. Show the correct 0 slack for
     real time tasks and enforce it at the core level instead of having
     inconsistent individual checks in various timer setup functions.

   - The usual set of updates and enhancements all over the place.

  Drivers:

   - Allow the ACPI PM timer to be turned off during suspend

   - No new drivers

   - The usual updates and enhancements in various drivers"

* tag 'timers-core-2024-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  ntp: Make sure RTC is synchronized when time goes backwards
  treewide: Fix wrong singular form of jiffies in comments
  cpu: Use already existing usleep_range()
  timers: Rename next_expiry_recalc() to be unique
  platform/x86:intel/pmc: Fix comment for the pmc_core_acpi_pm_timer_suspend_resume function
  clocksource/drivers/jcore: Use request_percpu_irq()
  clocksource/drivers/cadence-ttc: Add missing clk_disable_unprepare in ttc_setup_clockevent
  clocksource/drivers/asm9260: Add missing clk_disable_unprepare in asm9260_timer_init
  clocksource/drivers/qcom: Add missing iounmap() on errors in msm_dt_timer_init()
  clocksource/drivers/ingenic: Use devm_clk_get_enabled() helpers
  platform/x86:intel/pmc: Enable the ACPI PM Timer to be turned off when suspended
  clocksource: acpi_pm: Add external callback for suspend/resume
  clocksource/drivers/arm_arch_timer: Using for_each_available_child_of_node_scoped()
  dt-bindings: timer: rockchip: Add rk3576 compatible
  timers: Annotate possible non critical data race of next_expiry
  timers: Remove historical extra jiffie for timeout in msleep()
  hrtimer: Use and report correct timerslack values for realtime tasks
  hrtimer: Annotate hrtimer_cpu_base_.*_expiry() for sparse.
  timers: Add sparse annotation for timer_sync_wait_running().
  signal: Replace BUG_ON()s
  ...
 2024-09-17 07:25:37 +02:00
Linus Torvalds
e8fc317dfc vfs-6.12.procfs 
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZuQEwAAKCRCRxhvAZXjc
 onI2AQDXa5XhIx0VpLWE9uVImVy3QuUKc/5pI1e1DKMgxLhKCgEAh15a4ETqmVaw
 Zp3ZSzoLD8Ez1WwWb6cWQuHFYRSjtwU=
 =+LKG
 -----END PGP SIGNATURE-----

Merge tag 'vfs-6.12.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull procfs updates from Christian Brauner:
 "This contains the following changes for procfs:

   - Add config options and parameters to block forcing memory writes.

     This adds a Kconfig option and boot param to allow removing the
     FOLL_FORCE flag from /proc/<pid>/mem write calls as this can be
     used in various attacks.

     The traditional forcing behavior is kept as default because it can
     break GDB and some other use cases.

     This is the simpler version that you had requested.

   - Restrict overmounting of ephemeral entities.

     It is currently possible to mount on top of various ephemeral
     entities in procfs. This specifically includes magic links. To
     recap, magic links are links of the form /proc/<pid>/fd/<nr>. They
     serve as references to a target file and during path lookup they
     cause a jump to the target path. Such magic links disappear if the
     corresponding file descriptor is closed.

     Currently it is possible to overmount such magic links. This is
     mostly interesting for an attacker that wants to somehow trick a
     process into e.g., reopening something that it didn't intend to
     reopen or to hide a malicious file descriptor.

     But also it risks leaking mounts for long-running processes. When
     overmounting a magic link like above, the mount will not be
     detached when the file descriptor is closed. Only the target
     mountpoint will disappear. Which has the consequence of making it
     impossible to unmount that mount afterwards. So the mount will
     stick around until the process exits and the /proc/<pid>/ directory
     is cleaned up during proc_flush_pid() when the dentries are pruned
     and invalidated.

     That in turn means it's possible for a program to accidentally leak
     mounts and it's also possible to make a task leak mounts without
     it's knowledge if the attacker just keeps overmounting things under
     /proc/<pid>/fd/<nr>.

     Disallow overmounting of such ephemeral entities.

   - Cleanup the readdir method naming in some procfs file operations.

   - Replace kmalloc() and strcpy() with a simple kmemdup() call"

* tag 'vfs-6.12.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  proc: fold kmalloc() + strcpy() into kmemdup()
  proc: block mounting on top of /proc/<pid>/fdinfo/*
  proc: block mounting on top of /proc/<pid>/fd/*
  proc: block mounting on top of /proc/<pid>/map_files/*
  proc: add proc_splice_unmountable()
  proc: proc_readfdinfo() -> proc_fdinfo_iterate()
  proc: proc_readfd() -> proc_fd_iterate()
  proc: add config & param to block forcing mem writes
 2024-09-16 09:36:59 +02:00
Linus Torvalds
3352633ce6 vfs-6.12.file 
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZuQEwAAKCRCRxhvAZXjc
 osS0AQCgIpvey9oW5DMyMw6Bv0hFMRv95gbNQZfHy09iK+NMNAD9GALhb/4cMIVB
 7YrZGXEz454lpgcs8AnrOVjVNfctOQg=
 =e9s9
 -----END PGP SIGNATURE-----

Merge tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs file updates from Christian Brauner:
 "This is the work to cleanup and shrink struct file significantly.

  Right now, (focusing on x86) struct file is 232 bytes. After this
  series struct file will be 184 bytes aka 3 cacheline and a spare 8
  bytes for future extensions at the end of the struct.

  With struct file being as ubiquitous as it is this should make a
  difference for file heavy workloads and allow further optimizations in
  the future.

   - struct fown_struct was embedded into struct file letting it take up
     32 bytes in total when really it shouldn't even be embedded in
     struct file in the first place. Instead, actual users of struct
     fown_struct now allocate the struct on demand. This frees up 24
     bytes.

   - Move struct file_ra_state into the union containg the cleanup hooks
     and move f_iocb_flags out of the union. This closes a 4 byte hole
     we created earlier and brings struct file to 192 bytes. Which means
     struct file is 3 cachelines and we managed to shrink it by 40
     bytes.

   - Reorder struct file so that nothing crosses a cacheline.

     I suspect that in the future we will end up reordering some members
     to mitigate false sharing issues or just because someone does
     actually provide really good perf data.

   - Shrinking struct file to 192 bytes is only part of the work.

     Files use a slab that is SLAB_TYPESAFE_BY_RCU and when a kmem cache
     is created with SLAB_TYPESAFE_BY_RCU the free pointer must be
     located outside of the object because the cache doesn't know what
     part of the memory can safely be overwritten as it may be needed to
     prevent object recycling.

     That has the consequence that SLAB_TYPESAFE_BY_RCU may end up
     adding a new cacheline.

     So this also contains work to add a new kmem_cache_create_rcu()
     function that allows the caller to specify an offset where the
     freelist pointer is supposed to be placed. Thus avoiding the
     implicit addition of a fourth cacheline.

   - And finally this removes the f_version member in struct file.

     The f_version member isn't particularly well-defined. It is mainly
     used as a cookie to detect concurrent seeks when iterating
     directories. But it is also abused by some subsystems for
     completely unrelated things.

     It is mostly a directory and filesystem specific thing that doesn't
     really need to live in struct file and with its wonky semantics it
     really lacks a specific function.

     For pipes, f_version is (ab)used to defer poll notifications until
     a write has happened. And struct pipe_inode_info is used by
     multiple struct files in their ->private_data so there's no chance
     of pushing that down into file->private_data without introducing
     another pointer indirection.

     But pipes don't rely on f_pos_lock so this adds a union into struct
     file encompassing f_pos_lock and a pipe specific f_pipe member that
     pipes can use. This union of course can be extended to other file
     types and is similar to what we do in struct inode already"

* tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
  fs: remove f_version
  pipe: use f_pipe
  fs: add f_pipe
  ubifs: store cookie in private data
  ufs: store cookie in private data
  udf: store cookie in private data
  proc: store cookie in private data
  ocfs2: store cookie in private data
  input: remove f_version abuse
  ext4: store cookie in private data
  ext2: store cookie in private data
  affs: store cookie in private data
  fs: add generic_llseek_cookie()
  fs: use must_set_pos()
  fs: add must_set_pos()
  fs: add vfs_setpos_cookie()
  s390: remove unused f_version
  ceph: remove unused f_version
  adi: remove unused f_version
  mm: Removed @freeptr_offset to prevent doc warning
  ...
 2024-09-16 09:14:02 +02:00
Linus Torvalds
8f72c31f45 vfs-6.12.misc 
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZuQEGwAKCRCRxhvAZXjc
 ojIuAQC433+hBkvjvmQ7H0r5rgZSjUuCTG3bSmdU7RJmPHUHhwEA85v/NGq53f+W
 IhandK6t+Cf0JYpFZ3N0bT88hDYVhQQ=
 =9zGL
 -----END PGP SIGNATURE-----

Merge tag 'vfs-6.12.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "This contains the usual pile of misc updates:

  Features:

   - Add F_CREATED_QUERY fcntl() that allows userspace to query whether
     a file was actually created. Often userspace wants to know whether
     an O_CREATE request did actually create a file without using
     O_EXCL. The current logic is that to first attempts to open the
     file without O_CREAT | O_EXCL and if ENOENT is returned userspace
     tries again with both flags. If that succeeds all is well. If it
     now reports EEXIST it retries.

     That works fairly well but some corner cases make this more
     involved. If this operates on a dangling symlink the first openat()
     without O_CREAT | O_EXCL will return ENOENT but the second openat()
     with O_CREAT | O_EXCL will fail with EEXIST.

     The reason is that openat() without O_CREAT | O_EXCL follows the
     symlink while O_CREAT | O_EXCL doesn't for security reasons. So
     it's not something we can really change unless we add an explicit
     opt-in via O_FOLLOW which seems really ugly.

     All available workarounds are really nasty (fanotify, bpf lsm etc)
     so add a simple fcntl().

   - Try an opportunistic lookup for O_CREAT. Today, when opening a file
     we'll typically do a fast lookup, but if O_CREAT is set, the kernel
     always takes the exclusive inode lock. This was likely done with
     the expectation that O_CREAT means that we always expect to do the
     create, but that's often not the case. Many programs set O_CREAT
     even in scenarios where the file already exists (see related
     F_CREATED_QUERY patch motivation above).

     The series contained in the pr rearranges the pathwalk-for-open
     code to also attempt a fast_lookup in certain O_CREAT cases. If a
     positive dentry is found, the inode_lock can be avoided altogether
     and it can stay in rcuwalk mode for the last step_into.

   - Expose the 64 bit mount id via name_to_handle_at()

     Now that we provide a unique 64-bit mount ID interface in statx(2),
     we can now provide a race-free way for name_to_handle_at(2) to
     provide a file handle and corresponding mount without needing to
     worry about racing with /proc/mountinfo parsing or having to open a
     file just to do statx(2).

     While this is not necessary if you are using AT_EMPTY_PATH and
     don't care about an extra statx(2) call, users that pass full paths
     into name_to_handle_at(2) need to know which mount the file handle
     comes from (to make sure they don't try to open_by_handle_at a file
     handle from a different filesystem) and switching to AT_EMPTY_PATH
     would require allocating a file for every name_to_handle_at(2) call

   - Add a per dentry expire timeout to autofs

     There are two fairly well known automounter map formats, the autofs
     format and the amd format (more or less System V and Berkley).

     Some time ago Linux autofs added an amd map format parser that
     implemented a fair amount of the amd functionality. This was done
     within the autofs infrastructure and some functionality wasn't
     implemented because it either didn't make sense or required extra
     kernel changes. The idea was to restrict changes to be within the
     existing autofs functionality as much as possible and leave changes
     with a wider scope to be considered later.

     One of these changes is implementing the amd options:
      1) "unmount", expire this mount according to a timeout (same as
         the current autofs default).
      2) "nounmount", don't expire this mount (same as setting the
         autofs timeout to 0 except only for this specific mount) .
      3) "utimeout=<seconds>", expire this mount using the specified
         timeout (again same as setting the autofs timeout but only for
         this mount)

     To implement these options per-dentry expire timeouts need to be
     implemented for autofs indirect mounts. This is because all map
     keys (mounts) for autofs indirect mounts use an expire timeout
     stored in the autofs mount super block info. structure and all
     indirect mounts use the same expire timeout.

  Fixes:

   - Fix missing fput for FSCONFIG_SET_FD in autofs

   - Use param->file for FSCONFIG_SET_FD in coda

   - Delete the 'fs/netfs' proc subtreee when netfs module exits

   - Make sure that struct uid_gid_map fits into a single cacheline

   - Don't flush in-flight wb switches for superblocks without cgroup
     writeback

   - Correcting the idmapping mount example in the idmapping
     documentation

   - Fix a race between evice_inodes() and find_inode() and iput()

   - Refine the show_inode_state() macro definition in writeback code

   - Prevent dump_mapping() from accessing invalid dentry.d_name.name

   - Show actual source for debugfs in /proc/mounts

   - Annotate data-race of busy_poll_usecs in eventpoll

   - Don't WARN for racy path_noexec check in exec code

   - Handle OOM on mnt_warn_timestamp_expiry()

   - Fix some spelling in the iomap design documentation

   - Fix typo in procfs comment

   - Fix typo in fs/namespace.c comment

  Cleanups:

   - Add the VFS git tree to the MAINTAINERS file

   - Move FMODE_UNSIGNED_OFFSET to fop_flags freeing up another f_mode
     bit in struct file bringing us to 5 free f_mode bits

   - Remove the __I_DIO_WAKEUP bit from i_state flags as we can simplify
     the wait mechanism

   - Remove the unused path_put_init() helper

   - Replace a __u32 with u32 for s_fsnotify_mask as __u32 is uapi
     specific

   - Replace the unsigned long i_state member with a u32 i_state member
     in struct inode freeing up 4 bytes in struct inode. Instead of
     using the bit based wait apis we're now using the var event apis
     and using the individual bytes of the i_state member to wait on
     state changes

   - Explain how per-syscall AT_* flags should be allocated

   - Use in_group_or_capable() helper to simplify the posix acl mode
     update code

   - Switch to LIST_HEAD() in fsync_buffers_list() to simplify the code

   - Removed comment about d_rcu_to_refcount() as that function doesn't
     exist anymore

   - Add kernel documentation for lookup_fast()

   - Don't re-zero evenpoll fields

   - Remove outdated comment after close_fd()

   - Fix imprecise wording in comment about the pipe filesystem

   - Drop GFP_NOFAIL mode from alloc_page_buffers

   - Missing blank line warnings and struct declaration improved in
     file_table

   - Annotate struct poll_list with __counted_by()

   - Remove the unused read parameter in percpu-rwsem

   - Remove linux/prefetch.h include from direct-io code

   - Use kmemdup_array instead of kmemdup for multiple allocation in
     mnt_idmapping code

   - Remove unused mnt_cursor_del() declaration

  Performance tweaks:

   - Dodge smp_mb in break_lease and break_deleg in the common case

   - Only read fops once in fops_{get,put}()

   - Use RCU in ilookup()

   - Elide smp_mb in iversion handling in the common case

   - Drop one lock trip in evict()"

* tag 'vfs-6.12.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (58 commits)
  uidgid: make sure we fit into one cacheline
  proc: Fix typo in the comment
  fs/pipe: Correct imprecise wording in comment
  fhandle: expose u64 mount id to name_to_handle_at(2)
  uapi: explain how per-syscall AT_* flags should be allocated
  fs: drop GFP_NOFAIL mode from alloc_page_buffers
  writeback: Refine the show_inode_state() macro definition
  fs/inode: Prevent dump_mapping() accessing invalid dentry.d_name.name
  mnt_idmapping: Use kmemdup_array instead of kmemdup for multiple allocation
  netfs: Delete subtree of 'fs/netfs' when netfs module exits
  fs: use LIST_HEAD() to simplify code
  inode: make i_state a u32
  inode: port __I_LRU_ISOLATING to var event
  vfs: fix race between evice_inodes() and find_inode()&iput()
  inode: port __I_NEW to var event
  inode: port __I_SYNC to var event
  fs: reorder i_state bits
  fs: add i_state helpers
  MAINTAINERS: add the VFS git tree
  fs: s/__u32/u32/ for s_fsnotify_mask
  ...
 2024-09-16 08:35:09 +02:00
Christophe Leroy
d175ee98fe mm: Define VM_DROPPABLE for powerpc/32 
Commit 9651fcedf7 ("mm: add MAP_DROPPABLE for designating always
lazily freeable mappings") only adds VM_DROPPABLE for 64 bits
architectures.

In order to also use the getrandom vDSO implementation on powerpc/32,
use VM_ARCH_1 for VM_DROPPABLE on powerpc/32. This is possible because
VM_ARCH_1 is used for VM_SAO on powerpc and VM_SAO is only for
powerpc/64. It is used in combination with PROT_SAO in some parts of
code that are restricted to CONFIG_PPC64 through #ifdefs, it is
therefore possible to define VM_SAO for CONFIG_PPC64 only.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
 2024-09-13 17:28:36 +02:00
Christian Brauner
b4dba2efa8
proc: store cookie in private data 
Store the cookie to detect concurrent seeks on directories in
file->private_data.

Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-14-6d3e4816aa7b@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-09-12 11:58:44 +02:00
Alexey Dobriyan
4ad5f9a021
proc: fold kmalloc() + strcpy() into kmemdup() 
strcpy() will recalculate string length second time which is
unnecessary in this case.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://lore.kernel.org/r/90af27c1-0b86-47a6-a6c8-61a58b8aa747@p183
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-09-09 10:51:20 +02:00
Yan Zhen
698e7d1680
proc: Fix typo in the comment 
The deference here confuses me.

Maybe here want to say that because show_fd_locks() does not dereference
the files pointer, using the stale value of the files pointer is safe.

Correctly spelled comments make it easier for the reader to understand
the code.

replace 'deferences' with 'dereferences' in the comment &
replace 'inialized' with 'initialized' in the comment.

Signed-off-by: Yan Zhen <yanzhen@vivo.com>
Link: https://lore.kernel.org/r/20240909063353.2246419-1-yanzhen@vivo.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-09-09 09:51:16 +02:00
John Ogness
c83a20662d proc: Add nbcon support for /proc/consoles 
Update /proc/consoles output to show 'W' if an nbcon console is
registered. Since the write_thread() callback is mandatory, it
enough just to check if it is an nbcon console.

Also update /proc/consoles output to show 'N' if it is an
nbcon console.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-14-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
 2024-09-04 15:56:33 +02:00
John Ogness
fe6fa88d86 proc: consoles: Add notation to c_start/c_stop 
fs/proc/consoles.c:78:13: warning: context imbalance in 'c_start'
	- wrong count at exit
fs/proc/consoles.c:104:13: warning: context imbalance in 'c_stop'
	- unexpected unlock

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240904120536.115780-13-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
 2024-09-04 15:56:32 +02:00
Joey Gouly
9f82f15ddf mm: use ARCH_PKEY_BITS to define VM_PKEY_BITN 
Use the new CONFIG_ARCH_PKEY_BITS to simplify setting these bits
for different architectures.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20240822151113.1479789-4-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
 2024-09-04 12:52:40 +01:00
Christian Brauner
641bb4394f fs: move FMODE_UNSIGNED_OFFSET to fop_flags 
This is another flag that is statically set and doesn't need to use up
an FMODE_* bit. Move it to ->fop_flags and free up another FMODE_* bit.

(1) mem_open() used from proc_mem_operations
(2) adi_open() used from adi_fops
(3) drm_open_helper():
    (3.1) accel_open() used from DRM_ACCEL_FOPS
    (3.2) drm_open() used from
    (3.2.1) amdgpu_driver_kms_fops
    (3.2.2) psb_gem_fops
    (3.2.3) i915_driver_fops
    (3.2.4) nouveau_driver_fops
    (3.2.5) panthor_drm_driver_fops
    (3.2.6) radeon_driver_kms_fops
    (3.2.7) tegra_drm_fops
    (3.2.8) vmwgfx_driver_fops
    (3.2.9) xe_driver_fops
    (3.2.10) DRM_GEM_FOPS
    (3.2.11) DEFINE_DRM_GEM_DMA_FOPS
(4) struct memdev sets fmode flags based on type of device opened. For
    devices using struct mem_fops unsigned offset is used.

Mark all these file operations as FOP_UNSIGNED_OFFSET and add asserts
into the open helper to ensure that the flag is always set.

Link: https://lore.kernel.org/r/20240809-work-fop_unsigned-v1-1-658e054d893e@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:36 +02:00
Christian Brauner
d80b065bb1
Merge patch series "proc: restrict overmounting of ephemeral entities" 
Christian Brauner <brauner@kernel.org> says:

It is currently possible to mount on top of various ephemeral entities
in procfs. This specifically includes magic links. To recap, magic links
are links of the form /proc/<pid>/fd/<nr>. They serve as references to
a target file and during path lookup they cause a jump to the target
path. Such magic links disappear if the corresponding file descriptor is
closed.

Currently it is possible to overmount such magic links:

int fd = open("/mnt/foo", O_RDONLY);
sprintf(path, "/proc/%d/fd/%d", getpid(), fd);
int fd2 = openat(AT_FDCWD, path, O_PATH | O_NOFOLLOW);
mount("/mnt/bar", path, "", MS_BIND, 0);

Arguably, this is nonsensical and is mostly interesting for an attacker
that wants to somehow trick a process into e.g., reopening something
that they didn't intend to reopen or to hide a malicious file
descriptor.

But also it risks leaking mounts for long-running processes. When
overmounting a magic link like above, the mount will not be detached
when the file descriptor is closed. Only the target mountpoint will
disappear. Which has the consequence of making it impossible to unmount
that mount afterwards. So the mount will stick around until the process
exits and the /proc/<pid>/ directory is cleaned up during
proc_flush_pid() when the dentries are pruned and invalidated.

That in turn means it's possible for a program to accidentally leak
mounts and it's also possible to make a task leak mounts without it's
knowledge if the attacker just keeps overmounting things under
/proc/<pid>/fd/<nr>.

I think it's wrong to try and fix this by us starting to play games with
close() or somewhere else to undo these mounts when the file descriptor
is closed. The fact that we allow overmounting of such magic links is
simply a bug and one that we need to fix.

Similar things can be said about entries under fdinfo/ and map_files/ so
those are restricted as well.

I have a further more aggressive patch that gets out the big hammer and
makes everything under /proc/<pid>/*, as well as immediate symlinks such
as /proc/self, /proc/thread-self, /proc/mounts, /proc/net that point
into /proc/<pid>/ not overmountable. Imho, all of this should be blocked
if we can get away with it. It's only useful to hide exploits such as in [1].

And again, overmounting of any global procfs files remains unaffected
and is an existing and supported use-case.

Link: https://righteousit.com/2024/07/24/hiding-linux-processes-with-bind-mounts [1]

// Note that repro uses the traditional way of just mounting over
// /proc/<pid>/fd/<nr>. This could also all be achieved just based on
// file descriptors using move_mount(). So /proc/<pid>/fd/<nr> isn't the
// only entry vector here. It's also possible to e.g., mount directly
// onto /proc/<pid>/map_files/* without going over /proc/<pid>/fd/<nr>.
int main(int argc, char *argv[])
{
        char path[PATH_MAX];

        creat("/mnt/foo", 0777);
        creat("/mnt/bar", 0777);

        /*
         * For illustration use a bunch of file descriptors in the upper
         * range that are unused.
         */
        for (int i = 10000; i >= 256; i--) {
                printf("I'm: /proc/%d/\n", getpid());

                int fd2 = open("/mnt/foo", O_RDONLY);
                if (fd2 < 0) {
                        printf("%m - Failed to open\n");
                        _exit(1);
                }

                int newfd = dup2(fd2, i);
                if (newfd < 0) {
                        printf("%m - Failed to dup\n");
                        _exit(1);
                }
                close(fd2);

                sprintf(path, "/proc/%d/fd/%d", getpid(), newfd);
                int fd = openat(AT_FDCWD, path, O_PATH | O_NOFOLLOW);
                if (fd < 0) {
                        printf("%m - Failed to open\n");
                        _exit(3);
                }

                sprintf(path, "/proc/%d/fd/%d", getpid(), fd);
                printf("Mounting on top of %s\n", path);
                if (mount("/mnt/bar", path, "", MS_BIND, 0)) {
                        printf("%m - Failed to mount\n");
                        _exit(4);
                }

                close(newfd);
                close(fd2);
        }

        /*
         * Give some time to look at things. The mounts now linger until
         * the process exits.
         */
        sleep(10000);
        _exit(0);
}

* patches from https://lore.kernel.org/r/20240806-work-procfs-v1-0-fb04e1d09f0c@kernel.org:
  proc: block mounting on top of /proc/<pid>/fdinfo/*
  proc: block mounting on top of /proc/<pid>/fd/*
  proc: block mounting on top of /proc/<pid>/map_files/*
  proc: add proc_splice_unmountable()
  proc: proc_readfdinfo() -> proc_fdinfo_iterate()
  proc: proc_readfd() -> proc_fd_iterate()

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-0-fb04e1d09f0c@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:13 +02:00
Christian Brauner
cf71eaa1ad
proc: block mounting on top of /proc/<pid>/fdinfo/* 
Entries under /proc/<pid>/fdinfo/* are ephemeral and may go away before
the process dies. As such allowing them to be used as mount points
creates the ability to leak mounts that linger until the process dies
with no ability to unmount them until then. Don't allow using them as
mountpoints.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-6-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:13 +02:00
Christian Brauner
74ce208089
proc: block mounting on top of /proc/<pid>/fd/* 
Entries under /proc/<pid>/fd/* are ephemeral and may go away before the
process dies. As such allowing them to be used as mount points creates
the ability to leak mounts that linger until the process dies with no
ability to unmount them until then. Don't allow using them as
mountpoints.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-5-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:13 +02:00
Christian Brauner
3836b31c3e
proc: block mounting on top of /proc/<pid>/map_files/* 
Entries under /proc/<pid>/map_files/* are ephemeral and may go away
before the process dies. As such allowing them to be used as mount
points creates the ability to leak mounts that linger until the process
dies with no ability to unmount them until then. Don't allow using them
as mountpoints.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-4-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:12 +02:00
Christian Brauner
32a0a965b8
proc: add proc_splice_unmountable() 
Add a tiny procfs helper to splice a dentry that cannot be mounted upon.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-3-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:12 +02:00
Christian Brauner
55d4860db2
proc: proc_readfdinfo() -> proc_fdinfo_iterate() 
Give the method to iterate through the fdinfo directory a better name.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-2-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:22:05 +02:00
Christian Brauner
b69181b871
proc: proc_readfd() -> proc_fd_iterate() 
Give the method to iterate through the fd directory a better name.

Link: https://lore.kernel.org/r/20240806-work-procfs-v1-1-fb04e1d09f0c@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:21:34 +02:00
Adrian Ratiu
41e8149c88
proc: add config & param to block forcing mem writes 
This adds a Kconfig option and boot param to allow removing
the FOLL_FORCE flag from /proc/pid/mem write calls because
it can be abused.

The traditional forcing behavior is kept as default because
it can break GDB and some other use cases.

Previously we tried a more sophisticated approach allowing
distributions to fine-tune /proc/pid/mem behavior, however
that got NAK-ed by Linus [1], who prefers this simpler
approach with semantics also easier to understand for users.

Link: https://lore.kernel.org/lkml/CAHk-=wiGWLChxYmUA5HrT5aopZrB7_2VTa0NLZcxORgkUe5tEQ@mail.gmail.com/ [1]
Cc: Doug Anderson <dianders@chromium.org>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Link: https://lore.kernel.org/r/20240802080225.89408-1-adrian.ratiu@collabora.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-08-30 08:19:43 +02:00
Felix Moessbauer
ed4fb6d7ef hrtimer: Use and report correct timerslack values for realtime tasks 
The timerslack_ns setting is used to specify how much the hardware
timers should be delayed, to potentially dispatch multiple timers in a
single interrupt. This is a performance optimization. Timers of
realtime tasks (having a realtime scheduling policy) should not be
delayed.

This logic was inconsitently applied to the hrtimers, leading to delays
of realtime tasks which used timed waits for events (e.g. condition
variables). Due to the downstream override of the slack for rt tasks,
the procfs reported incorrect (non-zero) timerslack_ns values.

This is changed by setting the timer_slack_ns task attribute to 0 for
all tasks with a rt policy. By that, downstream users do not need to
specially handle rt tasks (w.r.t. the slack), and the procfs entry
shows the correct value of "0". Setting non-zero slack values (either
via procfs or PR_SET_TIMERSLACK) on tasks with a rt policy is ignored,
as stated in "man 2 PR_SET_TIMERSLACK":

  Timer slack is not applied to threads that are scheduled under a
  real-time scheduling policy (see sched_setscheduler(2)).

The special handling of timerslack on rt tasks in downstream users
is removed as well.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240814121032.368444-2-felix.moessbauer@siemens.com
 2024-08-23 20:13:02 +02:00
Thomas Gleixner
52dea0a15c posix-timers: Convert timer list to hlist 
No requirement for a real list. Spare a few bytes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
 2024-07-29 21:57:35 +02:00
Linus Torvalds
7a3fad30fd Random number generator updates for Linux 6.11-rc1. 
-----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEq5lC5tSkz8NBJiCnSfxwEqXeA64FAmaarzgACgkQSfxwEqXe
 A66ZWBAAlhXx8bve0uKlDRK8fffWHgruho/fOY4lZJ137AKwA9JCtmOyqdfL4Dmk
 VxFe7pEQJlQhcA/6kH54uO7SBXwfKlKZJth6SYnaCRMUIbFifHjjIQ0QqldjEKi0
 rP90Hu4FVsbwQC7u9i9lQj9n2P36zb6pn83BzpZQ/2PtoVCSCrdSJUe0Rxa3H3GN
 0+nNkDSXQt5otCByLaeE3x7KJgXLWL9+G2eFSFLTZ8rSVfMx1CdOIAG37WlLGdWm
 BaFYPDKMyBTVvVJBNgAe9YSqtrsZ5nlmLz+Z9wAe/hTL7RlL03kWUu34/Udcpull
 zzMDH0WMntiGK3eFQ2gOYSWqypvAjwHgn3BzqNmjUb69+89mZsdU1slcvnxWsUwU
 D3vphrscaqarF629tfsXti3jc5PoXwUTjROZVcCyeFPBhyAZgzK8xUvPpJO+RT+K
 EuUABob9cpA6FCpW/QeolDmMDhXlNT8QgsZu1juokZac2xP3Ly3REyEvT7HLbU2W
 ZJjbEqm1ppp3RmGELUOJbyhwsLrnbt+OMDO7iEWoG8aSFK4diBK/ZM6WvLMkr8Oi
 7ioXGIsYkCy3c47wpZKTrAapOPJp5keqNAiHSEbXw8mozp6429QAEZxNOcczgHKC
 Ea2JzRkctqutcIT+Slw/uUe//i1iSsIHXbE81fp5udcQTJcUByo=
 =P8aI
 -----END PGP SIGNATURE-----

Merge tag 'random-6.11-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:
 "This adds getrandom() support to the vDSO.

  First, it adds a new kind of mapping to mmap(2), MAP_DROPPABLE, which
  lets the kernel zero out pages anytime under memory pressure, which
  enables allocating memory that never gets swapped to disk but also
  doesn't count as being mlocked.

  Then, the vDSO implementation of getrandom() is introduced in a
  generic manner and hooked into random.c.

  Next, this is implemented on x86. (Also, though it's not ready for
  this pull, somebody has begun an arm64 implementation already)

  Finally, two vDSO selftests are added.

  There are also two housekeeping cleanup commits"

* tag 'random-6.11-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  MAINTAINERS: add random.h headers to RNG subsection
  random: note that RNDGETPOOL was removed in 2.6.9-rc2
  selftests/vDSO: add tests for vgetrandom
  x86: vdso: Wire up getrandom() vDSO implementation
  random: introduce generic vDSO getrandom() implementation
  mm: add MAP_DROPPABLE for designating always lazily freeable mappings
 2024-07-24 10:29:50 -07:00
Linus Torvalds
fbc90c042c - 875fa64577da ("mm/hugetlb_vmemmap: fix race with speculative PFN 
walkers") is known to cause a performance regression
   (https://lore.kernel.org/all/3acefad9-96e5-4681-8014-827d6be71c7a@linux.ibm.com/T/#mfa809800a7862fb5bdf834c6f71a3a5113eb83ff).
   Yu has a fix which I'll send along later via the hotfixes branch.
 
 - In the series "mm: Avoid possible overflows in dirty throttling" Jan
   Kara addresses a couple of issues in the writeback throttling code.
   These fixes are also targetted at -stable kernels.
 
 - Ryusuke Konishi's series "nilfs2: fix potential issues related to
   reserved inodes" does that.  This should actually be in the
   mm-nonmm-stable tree, along with the many other nilfs2 patches.  My bad.
 
 - More folio conversions from Kefeng Wang in the series "mm: convert to
   folio_alloc_mpol()"
 
 - Kemeng Shi has sent some cleanups to the writeback code in the series
   "Add helper functions to remove repeated code and improve readability of
   cgroup writeback"
 
 - Kairui Song has made the swap code a little smaller and a little
   faster in the series "mm/swap: clean up and optimize swap cache index".
 
 - In the series "mm/memory: cleanly support zeropage in
   vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
   Hildenbrand has reworked the rather sketchy handling of the use of the
   zeropage in MAP_SHARED mappings.  I don't see any runtime effects here -
   more a cleanup/understandability/maintainablity thing.
 
 - Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling of
   higher addresses, for aarch64.  The (poorly named) series is
   "Restructure va_high_addr_switch".
 
 - The core TLB handling code gets some cleanups and possible slight
   optimizations in Bang Li's series "Add update_mmu_tlb_range() to
   simplify code".
 
 - Jane Chu has improved the handling of our
   fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in the
   series "Enhance soft hwpoison handling and injection".
 
 - Jeff Johnson has sent a billion patches everywhere to add
   MODULE_DESCRIPTION() to everything.  Some landed in this pull.
 
 - In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang has
   simplified migration's use of hardware-offload memory copying.
 
 - Yosry Ahmed performs more folio API conversions in his series "mm:
   zswap: trivial folio conversions".
 
 - In the series "large folios swap-in: handle refault cases first",
   Chuanhua Han inches us forward in the handling of large pages in the
   swap code.  This is a cleanup and optimization, working toward the end
   objective of full support of large folio swapin/out.
 
 - In the series "mm,swap: cleanup VMA based swap readahead window
   calculation", Huang Ying has contributed some cleanups and a possible
   fixlet to his VMA based swap readahead code.
 
 - In the series "add mTHP support for anonymous shmem" Baolin Wang has
   taught anonymous shmem mappings to use multisize THP.  By default this
   is a no-op - users must opt in vis sysfs controls.  Dramatic
   improvements in pagefault latency are realized.
 
 - David Hildenbrand has some cleanups to our remaining use of
   page_mapcount() in the series "fs/proc: move page_mapcount() to
   fs/proc/internal.h".
 
 - David also has some highmem accounting cleanups in the series
   "mm/highmem: don't track highmem pages manually".
 
 - Build-time fixes and cleanups from John Hubbard in the series
   "cleanups, fixes, and progress towards avoiding "make headers"".
 
 - Cleanups and consolidation of the core pagemap handling from Barry
   Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
   and utilize them".
 
 - Lance Yang's series "Reclaim lazyfree THP without splitting" has
   reduced the latency of the reclaim of pmd-mapped THPs under fairly
   common circumstances.  A 10x speedup is seen in a microbenchmark.
 
   It does this by punting to aother CPU but I guess that's a win unless
   all CPUs are pegged.
 
 - hugetlb_cgroup cleanups from Xiu Jianfeng in the series
   "mm/hugetlb_cgroup: rework on cftypes".
 
 - Miaohe Lin's series "Some cleanups for memory-failure" does just that
   thing.
 
 - Is anyone reading this stuff?  If so, email me!
 
 - Someone other than SeongJae has developed a DAMON feature in Honggyu
   Kim's series "DAMON based tiered memory management for CXL memory".
   This adds DAMON features which may be used to help determine the
   efficiency of our placement of CXL/PCIe attached DRAM.
 
 - DAMON user API centralization and simplificatio work in SeongJae
   Park's series "mm/damon: introduce DAMON parameters online commit
   function".
 
 - In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
   David Hildenbrand does some maintenance work on zsmalloc - partially
   modernizing its use of pageframe fields.
 
 - Kefeng Wang provides more folio conversions in the series "mm: remove
   page_maybe_dma_pinned() and page_mkclean()".
 
 - More cleanup from David Hildenbrand, this time in the series
   "mm/memory_hotplug: use PageOffline() instead of PageReserved() for
   !ZONE_DEVICE".  It "enlightens memory hotplug more about PageOffline()
   pages" and permits the removal of some virtio-mem hacks.
 
 - Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
   __folio_add_anon_rmap()" is a cleanup to the anon folio handling in
   preparation for mTHP (multisize THP) swapin.
 
 - Kefeng Wang's series "mm: improve clear and copy user folio"
   implements more folio conversions, this time in the area of large folio
   userspace copying.
 
 - The series "Docs/mm/damon/maintaier-profile: document a mailing tool
   and community meetup series" tells people how to get better involved
   with other DAMON developers.  From SeongJae Park.
 
 - A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
   that.
 
 - David Hildenbrand sends along more cleanups, this time against the
   migration code.  The series is "mm/migrate: move NUMA hinting fault
   folio isolation + checks under PTL".
 
 - Jan Kara has found quite a lot of strangenesses and minor errors in
   the readahead code.  He addresses this in the series "mm: Fix various
   readahead quirks".
 
 - SeongJae Park's series "selftests/damon: test DAMOS tried regions and
   {min,max}_nr_regions" adds features and addresses errors in DAMON's self
   testing code.
 
 - Gavin Shan has found a userspace-triggerable WARN in the pagecache
   code.  The series "mm/filemap: Limit page cache size to that supported
   by xarray" addresses this.  The series is marked cc:stable.
 
 - Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
   and cleanup" cleans up and slightly optimizes KSM.
 
 - Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
   code motion.  The series (which also makes the memcg-v1 code
   Kconfigurable) are
 
   "mm: memcg: separate legacy cgroup v1 code and put under config
   option" and
   "mm: memcg: put cgroup v1-specific memcg data under CONFIG_MEMCG_V1"
 
 - Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
   adds an additional feature to this cgroup-v2 control file.
 
 - The series "Userspace controls soft-offline pages" from Jiaqi Yan
   permits userspace to stop the kernel's automatic treatment of excessive
   correctable memory errors.  In order to permit userspace to monitor and
   handle this situation.
 
 - Kefeng Wang's series "mm: migrate: support poison recover from migrate
   folio" teaches the kernel to appropriately handle migration from
   poisoned source folios rather than simply panicing.
 
 - SeongJae Park's series "Docs/damon: minor fixups and improvements"
   does those things.
 
 - In the series "mm/zsmalloc: change back to per-size_class lock"
   Chengming Zhou improves zsmalloc's scalability and memory utilization.
 
 - Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
   pinning memfd folios" makes the GUP code use FOLL_PIN rather than bare
   refcount increments.  So these paes can first be moved aside if they
   reside in the movable zone or a CMA block.
 
 - Andrii Nakryiko has added a binary ioctl()-based API to /proc/pid/maps
   for much faster reading of vma information.  The series is "query VMAs
   from /proc/<pid>/maps".
 
 - In the series "mm: introduce per-order mTHP split counters" Lance Yang
   improves the kernel's presentation of developer information related to
   multisize THP splitting.
 
 - Michael Ellerman has developed the series "Reimplement huge pages
   without hugepd on powerpc (8xx, e500, book3s/64)".  This permits
   userspace to use all available huge page sizes.
 
 - In the series "revert unconditional slab and page allocator fault
   injection calls" Vlastimil Babka removes a performance-affecting and not
   very useful feature from slab fault injection.
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCZp2C+QAKCRDdBJ7gKXxA
 joTkAQDvjqOoFStqk4GU3OXMYB7WCU/ZQMFG0iuu1EEwTVDZ4QEA8CnG7seek1R3
 xEoo+vw0sWWeLV3qzsxnCA1BJ8cTJA8=
 =z0Lf
 -----END PGP SIGNATURE-----

Merge tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - In the series "mm: Avoid possible overflows in dirty throttling" Jan
   Kara addresses a couple of issues in the writeback throttling code.
   These fixes are also targetted at -stable kernels.

 - Ryusuke Konishi's series "nilfs2: fix potential issues related to
   reserved inodes" does that. This should actually be in the
   mm-nonmm-stable tree, along with the many other nilfs2 patches. My
   bad.

 - More folio conversions from Kefeng Wang in the series "mm: convert to
   folio_alloc_mpol()"

 - Kemeng Shi has sent some cleanups to the writeback code in the series
   "Add helper functions to remove repeated code and improve readability
   of cgroup writeback"

 - Kairui Song has made the swap code a little smaller and a little
   faster in the series "mm/swap: clean up and optimize swap cache
   index".

 - In the series "mm/memory: cleanly support zeropage in
   vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
   Hildenbrand has reworked the rather sketchy handling of the use of
   the zeropage in MAP_SHARED mappings. I don't see any runtime effects
   here - more a cleanup/understandability/maintainablity thing.

 - Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling
   of higher addresses, for aarch64. The (poorly named) series is
   "Restructure va_high_addr_switch".

 - The core TLB handling code gets some cleanups and possible slight
   optimizations in Bang Li's series "Add update_mmu_tlb_range() to
   simplify code".

 - Jane Chu has improved the handling of our
   fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in
   the series "Enhance soft hwpoison handling and injection".

 - Jeff Johnson has sent a billion patches everywhere to add
   MODULE_DESCRIPTION() to everything. Some landed in this pull.

 - In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang
   has simplified migration's use of hardware-offload memory copying.

 - Yosry Ahmed performs more folio API conversions in his series "mm:
   zswap: trivial folio conversions".

 - In the series "large folios swap-in: handle refault cases first",
   Chuanhua Han inches us forward in the handling of large pages in the
   swap code. This is a cleanup and optimization, working toward the end
   objective of full support of large folio swapin/out.

 - In the series "mm,swap: cleanup VMA based swap readahead window
   calculation", Huang Ying has contributed some cleanups and a possible
   fixlet to his VMA based swap readahead code.

 - In the series "add mTHP support for anonymous shmem" Baolin Wang has
   taught anonymous shmem mappings to use multisize THP. By default this
   is a no-op - users must opt in vis sysfs controls. Dramatic
   improvements in pagefault latency are realized.

 - David Hildenbrand has some cleanups to our remaining use of
   page_mapcount() in the series "fs/proc: move page_mapcount() to
   fs/proc/internal.h".

 - David also has some highmem accounting cleanups in the series
   "mm/highmem: don't track highmem pages manually".

 - Build-time fixes and cleanups from John Hubbard in the series
   "cleanups, fixes, and progress towards avoiding "make headers"".

 - Cleanups and consolidation of the core pagemap handling from Barry
   Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
   and utilize them".

 - Lance Yang's series "Reclaim lazyfree THP without splitting" has
   reduced the latency of the reclaim of pmd-mapped THPs under fairly
   common circumstances. A 10x speedup is seen in a microbenchmark.

   It does this by punting to aother CPU but I guess that's a win unless
   all CPUs are pegged.

 - hugetlb_cgroup cleanups from Xiu Jianfeng in the series
   "mm/hugetlb_cgroup: rework on cftypes".

 - Miaohe Lin's series "Some cleanups for memory-failure" does just that
   thing.

 - Someone other than SeongJae has developed a DAMON feature in Honggyu
   Kim's series "DAMON based tiered memory management for CXL memory".
   This adds DAMON features which may be used to help determine the
   efficiency of our placement of CXL/PCIe attached DRAM.

 - DAMON user API centralization and simplificatio work in SeongJae
   Park's series "mm/damon: introduce DAMON parameters online commit
   function".

 - In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
   David Hildenbrand does some maintenance work on zsmalloc - partially
   modernizing its use of pageframe fields.

 - Kefeng Wang provides more folio conversions in the series "mm: remove
   page_maybe_dma_pinned() and page_mkclean()".

 - More cleanup from David Hildenbrand, this time in the series
   "mm/memory_hotplug: use PageOffline() instead of PageReserved() for
   !ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline()
   pages" and permits the removal of some virtio-mem hacks.

 - Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
   __folio_add_anon_rmap()" is a cleanup to the anon folio handling in
   preparation for mTHP (multisize THP) swapin.

 - Kefeng Wang's series "mm: improve clear and copy user folio"
   implements more folio conversions, this time in the area of large
   folio userspace copying.

 - The series "Docs/mm/damon/maintaier-profile: document a mailing tool
   and community meetup series" tells people how to get better involved
   with other DAMON developers. From SeongJae Park.

 - A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
   that.

 - David Hildenbrand sends along more cleanups, this time against the
   migration code. The series is "mm/migrate: move NUMA hinting fault
   folio isolation + checks under PTL".

 - Jan Kara has found quite a lot of strangenesses and minor errors in
   the readahead code. He addresses this in the series "mm: Fix various
   readahead quirks".

 - SeongJae Park's series "selftests/damon: test DAMOS tried regions and
   {min,max}_nr_regions" adds features and addresses errors in DAMON's
   self testing code.

 - Gavin Shan has found a userspace-triggerable WARN in the pagecache
   code. The series "mm/filemap: Limit page cache size to that supported
   by xarray" addresses this. The series is marked cc:stable.

 - Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
   and cleanup" cleans up and slightly optimizes KSM.

 - Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
   code motion. The series (which also makes the memcg-v1 code
   Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put
   under config option" and "mm: memcg: put cgroup v1-specific memcg
   data under CONFIG_MEMCG_V1"

 - Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
   adds an additional feature to this cgroup-v2 control file.

 - The series "Userspace controls soft-offline pages" from Jiaqi Yan
   permits userspace to stop the kernel's automatic treatment of
   excessive correctable memory errors. In order to permit userspace to
   monitor and handle this situation.

 - Kefeng Wang's series "mm: migrate: support poison recover from
   migrate folio" teaches the kernel to appropriately handle migration
   from poisoned source folios rather than simply panicing.

 - SeongJae Park's series "Docs/damon: minor fixups and improvements"
   does those things.

 - In the series "mm/zsmalloc: change back to per-size_class lock"
   Chengming Zhou improves zsmalloc's scalability and memory
   utilization.

 - Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
   pinning memfd folios" makes the GUP code use FOLL_PIN rather than
   bare refcount increments. So these paes can first be moved aside if
   they reside in the movable zone or a CMA block.

 - Andrii Nakryiko has added a binary ioctl()-based API to
   /proc/pid/maps for much faster reading of vma information. The series
   is "query VMAs from /proc/<pid>/maps".

 - In the series "mm: introduce per-order mTHP split counters" Lance
   Yang improves the kernel's presentation of developer information
   related to multisize THP splitting.

 - Michael Ellerman has developed the series "Reimplement huge pages
   without hugepd on powerpc (8xx, e500, book3s/64)". This permits
   userspace to use all available huge page sizes.

 - In the series "revert unconditional slab and page allocator fault
   injection calls" Vlastimil Babka removes a performance-affecting and
   not very useful feature from slab fault injection.

* tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits)
  mm/mglru: fix ineffective protection calculation
  mm/zswap: fix a white space issue
  mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio
  mm/hugetlb: fix possible recursive locking detected warning
  mm/gup: clear the LRU flag of a page before adding to LRU batch
  mm/numa_balancing: teach mpol_to_str about the balancing mode
  mm: memcg1: convert charge move flags to unsigned long long
  alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
  lib: reuse page_ext_data() to obtain codetag_ref
  lib: add missing newline character in the warning message
  mm/mglru: fix overshooting shrinker memory
  mm/mglru: fix div-by-zero in vmpressure_calc_level()
  mm/kmemleak: replace strncpy() with strscpy()
  mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
  mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
  mm: ignore data-race in __swap_writepage
  hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
  mm: shmem: rename mTHP shmem counters
  mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async()
  mm/migrate: putback split folios when numa hint migration fails
  ...
 2024-07-21 17:15:46 -07:00
Jason A. Donenfeld
9651fcedf7 mm: add MAP_DROPPABLE for designating always lazily freeable mappings 
The vDSO getrandom() implementation works with a buffer allocated with a
new system call that has certain requirements:

- It shouldn't be written to core dumps.
  * Easy: VM_DONTDUMP.
- It should be zeroed on fork.
  * Easy: VM_WIPEONFORK.

- It shouldn't be written to swap.
  * Uh-oh: mlock is rlimited.
  * Uh-oh: mlock isn't inherited by forks.

- It shouldn't reserve actual memory, but it also shouldn't crash when
  page faulting in memory if none is available
  * Uh-oh: VM_NORESERVE means segfaults.

It turns out that the vDSO getrandom() function has three really nice
characteristics that we can exploit to solve this problem:

1) Due to being wiped during fork(), the vDSO code is already robust to
   having the contents of the pages it reads zeroed out midway through
   the function's execution.

2) In the absolute worst case of whatever contingency we're coding for,
   we have the option to fallback to the getrandom() syscall, and
   everything is fine.

3) The buffers the function uses are only ever useful for a maximum of
   60 seconds -- a sort of cache, rather than a long term allocation.

These characteristics mean that we can introduce VM_DROPPABLE, which
has the following semantics:

a) It never is written out to swap.
b) Under memory pressure, mm can just drop the pages (so that they're
   zero when read back again).
c) It is inherited by fork.
d) It doesn't count against the mlock budget, since nothing is locked.
e) If there's not enough memory to service a page fault, it's not fatal,
   and no signal is sent.

This way, allocations used by vDSO getrandom() can use:

    VM_DROPPABLE | VM_DONTDUMP | VM_WIPEONFORK | VM_NORESERVE

And there will be no problem with OOMing, crashing on overcommitment,
using memory when not in use, not wiping on fork(), coredumps, or
writing out to swap.

In order to let vDSO getrandom() use this, expose these via mmap(2) as
MAP_DROPPABLE.

Note that this involves removing the MADV_FREE special case from
sort_folio(), which according to Yu Zhao is unnecessary and will simply
result in an extra call to shrink_folio_list() in the worst case. The
chunk removed reenables the swapbacked flag, which we don't want for
VM_DROPPABLE, and we can't conditionalize it here because there isn't a
vma reference available.

Finally, the provided self test ensures that this is working as desired.

Cc: linux-mm@kvack.org
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
 2024-07-19 20:22:12 +02:00
Linus Torvalds
f8a8b94d06 sysctl changes for 6.11-rc1 
Summary
 
 * Remove "->procname == NULL" check when iterating through sysctl table arrays
 
     Removing sentinels in ctl_table arrays reduces the build time size and
     runtime memory consumed by ~64 bytes per array. With all ctl_table
     sentinels gone, the additional check for ->procname == NULL that worked in
     tandem with the ARRAY_SIZE to calculate the size of the ctl_table arrays is
     no longer needed and has been removed. The sysctl register functions now
     returns an error if a sentinel is used.
 
 * Preparation patches for sysctl constification
 
     Constifying ctl_table structs prevents the modification of proc_handler
     function pointers as they would reside in .rodata. The ctl_table arguments
     in sysctl utility functions are const qualified in preparation for a future
     treewide proc_handler argument constification commit.
 
 * Misc fixes
 
     Increase robustness of set_ownership by providing sane default ownership
     values in case the callee doesn't set them. Bound check proc_dou8vec_minmax
     to avoid loading buggy modules and give sysctl testing module a name to
     avoid compiler complaints.
 
 Testing
 
   * This got push to linux-next in v6.10-rc2, so it has had more than a month
     of testing
 -----BEGIN PGP SIGNATURE-----
 
 iQGzBAABCgAdFiEErkcJVyXmMSXOyyeQupfNUreWQU8FAmaWdz4ACgkQupfNUreW
 QU/WKQwAkSuUz42yCQye77BK+Z8ANcTF1f3aI/wfv2nahq1GaSrNBpqUiXvEe9Tt
 KD2lM1PWiQfizVLIDPh96yxa5q69GQrPPOA/V1jwIXmk/HRpjjoONCFNNXVRCTls
 VCqDz/RatuXvzO35Yn87MnWnxv6PiX7X/zq/3WikVsUI381kvTgC6OwZxdFM52w4
 ESwOa3LeOovtRnqV5dpHr6DCQKyd0N52nPxgXvaerjlsJsv7PlezN7z9YyLOOfmW
 xUD7X6LQcJq7HcEukaB6I9o2GQOi4yYXL2YOzed7qu9Thu+lasEoN3Bd7P+ilXkc
 JY6EXJ5o+d69PewKRuJ1QvD7wrHIkhNMNbMtvehNay124wAHDy3KtonFzyvlX4wE
 qCHBYc6rySJNhSqwVp9MoksOZfDM99pVIOs9YVIjc90Zzu5J7tORgYWRVOHTcAtj
 fd8nMdkK3+ZANapygFCyew6GueIzaqlQwveVgLGw4vc5L3ClknmURit3y487Pzdg
 B+BEVlsp
 =bs2G
 -----END PGP SIGNATURE-----

Merge tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

Pull sysctl updates from Joel Granados:

 - Remove "->procname == NULL" check when iterating through sysctl table
   arrays

   Removing sentinels in ctl_table arrays reduces the build time size
   and runtime memory consumed by ~64 bytes per array. With all
   ctl_table sentinels gone, the additional check for ->procname == NULL
   that worked in tandem with the ARRAY_SIZE to calculate the size of
   the ctl_table arrays is no longer needed and has been removed. The
   sysctl register functions now returns an error if a sentinel is used.

 - Preparation patches for sysctl constification

   Constifying ctl_table structs prevents the modification of
   proc_handler function pointers as they would reside in .rodata. The
   ctl_table arguments in sysctl utility functions are const qualified
   in preparation for a future treewide proc_handler argument
   constification commit.

 - Misc fixes

   Increase robustness of set_ownership by providing sane default
   ownership values in case the callee doesn't set them. Bound check
   proc_dou8vec_minmax to avoid loading buggy modules and give sysctl
   testing module a name to avoid compiler complaints.

* tag 'sysctl-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
  sysctl: Warn on an empty procname element
  sysctl: Remove ctl_table sentinel code comments
  sysctl: Remove "child" sysctl code comments
  sysctl: Remove superfluous empty allocations from sysctl internals
  sysctl: Replace nr_entries with ctl_table_size in new_links
  sysctl: Remove check for sentinel element in ctl_table arrays
  mm profiling: Remove superfluous sentinel element from ctl_table
  locking: Remove superfluous sentinel element from kern_lockdep_table
  sysctl: Add module description to sysctl-testing
  sysctl: constify ctl_table arguments of utility function
  utsname: constify ctl_table arguments of utility function
  sysctl: move the extra1/2 boundary check of u8 to sysctl_check_table_array
  sysctl: always initialize i_uid/i_gid
 2024-07-16 14:24:29 -07:00
Linus Torvalds
b051320d6a vfs-6.11.misc 
-----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCZpEF0AAKCRCRxhvAZXjc
 oq0TAQDjfTLN75RwKQ34RIFtRun2q+OMfBQtSegtaccqazghyAD/QfmPuZDxB5DL
 rsI/5k5O4VupIKrEdIaqvNxmkmDsSAc=
 =bf7E
 -----END PGP SIGNATURE-----

Merge tag 'vfs-6.11.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Support passing NULL along AT_EMPTY_PATH for statx().

     NULL paths with any flag value other than AT_EMPTY_PATH go the
     usual route and end up with -EFAULT to retain compatibility (Rust
     is abusing calls of the sort to detect availability of statx)

     This avoids path lookup code, lockref management, memory allocation
     and in case of NULL path userspace memory access (which can be
     quite expensive with SMAP on x86_64)

   - Don't block i_writecount during exec. Remove the
     deny_write_access() mechanism for executables

   - Relax open_by_handle_at() permissions in specific cases where we
     can prove that the caller had sufficient privileges to open a file

   - Switch timespec64 fields in struct inode to discrete integers
     freeing up 4 bytes

  Fixes:

   - Fix false positive circular locking warning in hfsplus

   - Initialize hfs_inode_info after hfs_alloc_inode() in hfs

   - Avoid accidental overflows in vfs_fallocate()

   - Don't interrupt fallocate with EINTR in tmpfs to avoid constantly
     restarting shmem_fallocate()

   - Add missing quote in comment in fs/readdir

  Cleanups:

   - Don't assign and test in an if statement in mqueue. Move the
     assignment out of the if statement

   - Reflow the logic in may_create_in_sticky()

   - Remove the usage of the deprecated ida_simple_xx() API from procfs

   - Reject FSCONFIG_CMD_CREATE_EXCL requets that depend on the new
     mount api early

   - Rename variables in copy_tree() to make it easier to understand

   - Replace WARN(down_read_trylock, ...) abuse with proper asserts in
     various places in the VFS

   - Get rid of user_path_at_empty() and drop the empty argument from
     getname_flags()

   - Check for error while copying and no path in one branch in
     getname_flags()

   - Avoid redundant smp_mb() for THP handling in do_dentry_open()

   - Rename parent_ino to d_parent_ino and make it use RCU

   - Remove unused header include in fs/readdir

   - Export in_group_capable() helper and switch f2fs and fuse over to
     it instead of open-coding the logic in both places"

* tag 'vfs-6.11.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
  ipc: mqueue: remove assignment from IS_ERR argument
  vfs: rename parent_ino to d_parent_ino and make it use RCU
  vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)
  stat: use vfs_empty_path() helper
  fs: new helper vfs_empty_path()
  fs: reflow may_create_in_sticky()
  vfs: remove redundant smp_mb for thp handling in do_dentry_open
  fuse: Use in_group_or_capable() helper
  f2fs: Use in_group_or_capable() helper
  fs: Export in_group_or_capable()
  vfs: reorder checks in may_create_in_sticky
  hfs: fix to initialize fields of hfs_inode_info after hfs_alloc_inode()
  proc: Remove usage of the deprecated ida_simple_xx() API
  hfsplus: fix to avoid false alarm of circular locking
  Improve readability of copy_tree
  vfs: shave a branch in getname_flags
  vfs: retire user_path_at_empty and drop empty arg from getname_flags
  vfs: stop using user_path_at_empty in do_readlinkat
  tmpfs: don't interrupt fallocate with EINTR
  fs: don't block i_writecount during exec
  ...
 2024-07-15 10:52:51 -07:00
Ran Xiaokai
4c8763e84a kpageflags: detect isolated KPF_THP folios 
When folio is isolated, the PG_lru bit is cleared.  So the PG_lru check in
stable_page_flags() will miss this kind of isolated folios.  Use
folio_test_large_rmappable() instead to also include isolated folios.

Since pagecache supports large folios and the introduction of mTHP, the
semantics of KPF_THP have been expanded, now it indicates not only
PMD-sized THP.  Update related documentation to clearly state that KPF_THP
indicates multiple order THPs.

[ran.xiaokai@zte.com.cn: directly use is_zero_folio(), per David]
  Link: https://lkml.kernel.org/r/20240708062601.165215-1-ranxiaokai627@163.com
Link: https://lkml.kernel.org/r/20240705104343.112680-1-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrei Vagin <avagin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Svetly Todorov <svetly.todorov@memverge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-12 15:52:21 -07:00
Christophe Leroy
e6c0c03245 mm: provide mm_struct and address to huge_ptep_get() 
On powerpc 8xx huge_ptep_get() will need to know whether the given ptep is
a PTE entry or a PMD entry.  This cannot be known with the PMD entry
itself because there is no easy way to know it from the content of the
entry.

So huge_ptep_get() will need to know either the size of the page or get
the pmd.

In order to be consistent with huge_ptep_get_and_clear(), give mm and
address to huge_ptep_get().

Link: https://lkml.kernel.org/r/cc00c70dd384298796a4e1b25d6c4eb306d3af85.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-12 15:52:15 -07:00
Andrii Nakryiko
bfc69fd05e fs/procfs: add build ID fetching to PROCMAP_QUERY API 
The need to get ELF build ID reliably is an important aspect when dealing
with profiling and stack trace symbolization, and /proc/<pid>/maps textual
representation doesn't help with this.

To get backing file's ELF build ID, application has to first resolve VMA,
then use it's start/end address range to follow a special
/proc/<pid>/map_files/<start>-<end> symlink to open the ELF file (this is
necessary because backing file might have been removed from the disk or
was already replaced with another binary in the same file path.

Such approach, beyond just adding complexity of having to do a bunch of
extra work, has extra security implications.  Because application opens
underlying ELF file and needs read access to its entire contents (as far
as kernel is concerned), kernel puts additional capable() checks on
following /proc/<pid>/map_files/<start>-<end> symlink.  And that makes
sense in general.

But in the case of build ID, profiler/symbolizer doesn't need the contents
of ELF file, per se.  It's only build ID that is of interest, and ELF
build ID itself doesn't provide any sensitive information.

So this patch adds a way to request backing file's ELF build ID along the
rest of VMA information in the same API.  User has control over whether
this piece of information is requested or not by either setting
build_id_size field to zero or non-zero maximum buffer size they provided
through build_id_addr field (which encodes user pointer as __u64 field). 
This is a completely optional piece of information, and so has no
performance implications for user cases that don't care about build ID,
while improving performance and simplifying the setup for those
application that do need it.

Kernel already implements build ID fetching, which is used from BPF
subsystem.  We are reusing this code here, but plan a follow up changes to
make it work better under more relaxed assumption (compared to what
existing code assumes) of being called from user process context, in which
page faults are allowed.  BPF-specific implementation currently bails out
if necessary part of ELF file is not paged in, all due to extra
BPF-specific restrictions (like the need to fetch build ID in restrictive
contexts such as NMI handler).

[andrii@kernel.org: fix integer to pointer cast warning in do_procmap_query()]
  Link: https://lkml.kernel.org/r/20240701174805.1897344-1-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-4-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-12 15:52:12 -07:00
Andrii Nakryiko
ed5d583a88 fs/procfs: implement efficient VMA querying API for /proc/<pid>/maps 
/proc/<pid>/maps file is extremely useful in practice for various tasks
involving figuring out process memory layout, what files are backing any
given memory range, etc.  One important class of applications that
absolutely rely on this are profilers/stack symbolizers (perf tool being
one of them).  Patterns of use differ, but they generally would fall into
two categories.

In on-demand pattern, a profiler/symbolizer would normally capture stack
trace containing absolute memory addresses of some functions, and would
then use /proc/<pid>/maps file to find corresponding backing ELF files
(normally, only executable VMAs are of interest), file offsets within
them, and then continue from there to get yet more information (ELF
symbols, DWARF information) to get human-readable symbolic information. 
This pattern is used by Meta's fleet-wide profiler, as one example.

In preprocessing pattern, application doesn't know the set of addresses of
interest, so it has to fetch all relevant VMAs (again, probably only
executable ones), store or cache them, then proceed with profiling and
stack trace capture.  Once done, it would do symbolization based on stored
VMA information.  This can happen at much later point in time.  This
patterns is used by perf tool, as an example.

In either case, there are both performance and correctness requirement
involved.  This address to VMA information translation has to be done as
efficiently as possible, but also not miss any VMA (especially in the case
of loading/unloading shared libraries).  In practice, correctness can't be
guaranteed (due to process dying before VMA data can be captured, or
shared library being unloaded, etc), but any effort to maximize the chance
of finding the VMA is appreciated.

Unfortunately, for all the /proc/<pid>/maps file universality and
usefulness, it doesn't fit the above use cases 100%.

First, it's main purpose is to emit all VMAs sequentially, but in practice
captured addresses would fall only into a smaller subset of all process'
VMAs, mainly containing executable text.  Yet, library would need to parse
most or all of the contents to find needed VMAs, as there is no way to
skip VMAs that are of no use.  Efficient library can do the linear pass
and it is still relatively efficient, but it's definitely an overhead that
can be avoided, if there was a way to do more targeted querying of the
relevant VMA information.

Second, it's a text based interface, which makes its programmatic use from
applications and libraries more cumbersome and inefficient due to the need
to handle text parsing to get necessary pieces of information.  The
overhead is actually payed both by kernel, formatting originally binary
VMA data into text, and then by user space application, parsing it back
into binary data for further use.

For the on-demand pattern of usage, described above, another problem when
writing generic stack trace symbolization library is an unfortunate
performance-vs-correctness tradeoff that needs to be made.  Library has to
make a decision to either cache parsed contents of /proc/<pid>/maps (after
initial processing) to service future requests (if application requests to
symbolize another set of addresses (for the same process), captured at
some later time, which is typical for periodic/continuous profiling cases)
to avoid higher costs of re-parsing this file.  Or it has to choose to
cache the contents in memory to speed up future requests.  In the former
case, more memory is used for the cache and there is a risk of getting
stale data if application loads or unloads shared libraries, or otherwise
changed its set of VMAs somehow, e.g., through additional mmap() calls. 
In the latter case, it's the performance hit that comes from re-opening
the file and re-parsing its contents all over again.

This patch aims to solve this problem by providing a new API built on top
of /proc/<pid>/maps.  It's meant to address both non-selectiveness and
text nature of /proc/<pid>/maps, by giving user more control of what sort
of VMA(s) needs to be queried, and being binary-based interface eliminates
the overhead of text formatting (on kernel side) and parsing (on user
space side).

It's also designed to be extensible and forward/backward compatible by
including required struct size field, which user has to provide.  We use
established copy_struct_from_user() approach to handle extensibility.

User has a choice to pick either getting VMA that covers provided address
or -ENOENT if none is found (exact, least surprising, case).  Or, with an
extra query flag (PROCMAP_QUERY_COVERING_OR_NEXT_VMA), they can get either
VMA that covers the address (if there is one), or the closest next VMA
(i.e., VMA with the smallest vm_start > addr).  The latter allows more
efficient use, but, given it could be a surprising behavior, requires an
explicit opt-in.

There is another query flag that is useful for some use cases. 
PROCMAP_QUERY_FILE_BACKED_VMA instructs this API to only return
file-backed VMAs.  Combining this with PROCMAP_QUERY_COVERING_OR_NEXT_VMA
makes it possible to efficiently iterate only file-backed VMAs of the
process, which is what profilers/symbolizers are normally interested in.

All the above querying flags can be combined with (also optional) set of
desired VMA permissions flags.  This allows to, for example, iterate only
an executable subset of VMAs, which is what preprocessing pattern, used by
perf tool, would benefit from, as the assumption is that captured stack
traces would have addresses of executable code.  This saves time by
skipping non-executable VMAs altogether efficienty.

All these querying flags (modifiers) are orthogonal and can be combined in
a semantically meaningful and natural way.

Basing this ioctl()-based API on top of /proc/<pid>/maps's FD makes sense
given it's querying the same set of VMA data.  It's also benefitial
because permission checks for /proc/<pid>/maps is performed at open time
once, and the actual data read of text contents of /proc/<pid>/maps is
done without further permission checks.  We piggyback on this pattern with
ioctl()-based API as well, as that's a desired property.  Both for
performance reasons, but also for security and flexibility reasons.

Allowing application to open an FD for /proc/self/maps without any extra
capabilities, and then passing it to some sort of profiling agent through
Unix-domain socket, would allow such profiling agent to not require some
of the capabilities that are otherwise expected when opening
/proc/<pid>/maps file for *another* process.  This is a desirable property
for some more restricted setups.

This new ioctl-based implementation doesn't interfere with seq_file-based
implementation of /proc/<pid>/maps textual interface, and so could be used
together or independently without paying any price for that.

Note also, that fetching VMA name (e.g., backing file path, or special
hard-coded or user-provided names) is optional just like build ID.  If
user sets vma_name_size to zero, kernel code won't attempt to retrieve it,
saving resources.

Earlier versions of this patch set were adding per-VMA locking, which is
why we have a code structure that is ready for abstracting mmap_lock vs
vm_lock differences (query_vma_setup(), query_vma_teardown(), and
query_vma_find_by_addr()), but given anon_vma_name() is not yet compatible
with per-VMA locking, initial implementation sticks to using only
mmap_lock for now.  It will be easy to add back per-VMA locking once all
the pieces are ready later on.  Which is why we keep existing code
structure with setup/teardown/query helper functions.

[andrii@kernel.org: improve PROCMAP_QUERY's compat mode handling]
  Link: https://lkml.kernel.org/r/20240701174805.1897344-2-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-3-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-12 15:52:11 -07:00
Andrii Nakryiko
acd4b2ecf3 fs/procfs: extract logic for getting VMA name constituents 
Patch series "ioctl()-based API to query VMAs from /proc/<pid>/maps", v6.

Implement binary ioctl()-based interface to /proc/<pid>/maps file to allow
applications to query VMA information more efficiently than reading *all*
VMAs nonselectively through text-based interface of /proc/<pid>/maps file.

Patch #2 goes into a lot of details and background on some common patterns
of using /proc/<pid>/maps in the area of performance profiling and
subsequent symbolization of captured stack traces.  As mentioned in that
patch, patterns of VMA querying can differ depending on specific use case,
but can generally be grouped into two main categories: the need to query a
small subset of VMAs covering a given batch of addresses, or
reading/storing/caching all (typically, executable) VMAs upfront for later
processing.

The new PROCMAP_QUERY ioctl() API added in this patch set was motivated by
the former pattern of usage.  Earlier revisions had a patch adding a tool
that faithfully reproduces an efficient VMA matching pass of a symbolizer,
collecting a subset of covering VMAs for a given set of addresses as
efficiently as possible.  This tool served both as a testing ground, as
well as a benchmarking tool.  It implements everything both for currently
existing text-based /proc/<pid>/maps interface, as well as for newly-added
PROCMAP_QUERY ioctl().  This revision dropped the tool from the patch set
and, once the API lands upstream, this tool might be added separately on
Github as an example.

Based on discussion on earlier revisions of this patch set, it turned out
that this ioctl() API is competitive with highly-optimized text-based
pre-processing pattern that perf tool is using.  Based on perf discussion,
this revision adds more flexibility in specifying a subset of VMAs that
are of interest.  Now it's possible to specify desired permissions of VMAs
(e.g., request only executable ones) and/or restrict to only a subset of
VMAs that have file backing.  This further improves the efficiency when
using this new API thanks to more selective (executable VMAs only)
querying.

In addition to a custom benchmarking tool, and experimental perf
integration (available at [0]), Daniel Mueller has since also implemented
an experimental integration into blazesym (see [1]), a library used for
stack trace symbolization by our server fleet-wide profiler and another
on-device profiler agent that runs on weaker ARM devices.  The latter
ARM-based device profiler is especially sensitive to performance, and so
we benchmarked and compared text-based /proc/<pid>/maps solution to the
equivalent one using PROCMAP_QUERY ioctl().

Results are very encouraging, giving us 5x improvement for end-to-end
so-called "address normalization" pass, which is the part of the
symbolization process that happens locally on ARM device, before being
sent out for further heavier-weight processing on more powerful remote
server.  Note that this is not an artificial microbenchmark.  It's a full
end-to-end API call being measured with real-world data on real-world
device.

  TEXT-BASED
  ==========
  Benchmarking main/normalize_process_no_build_ids_uncached_maps
  main/normalize_process_no_build_ids_uncached_maps
	  time:   [49.777 µs 49.982 µs 50.250 µs]

  IOCTL-BASED
  ===========
  Benchmarking main/normalize_process_no_build_ids_uncached_maps
  main/normalize_process_no_build_ids_uncached_maps
	  time:   [10.328 µs 10.391 µs 10.457 µs]
	  change: [−79.453% −79.304% −79.166%] (p = 0.00 < 0.02)
	  Performance has improved.

You can see above that we see the drop from 50µs down to 10µs for
exactly the same amount of work, with the same data and target process.

With the aforementioned custom tool, we see about ~40x improvement (it
might vary a bit, depending on a specific captured set of addresses).  And
even for perf-based benchmark it's on par or slightly ahead when using
permission-based filtering (fetching only executable VMAs).

Earlier revisions attempted to use per-VMA locking, if kernel was compiled
with CONFIG_PER_VMA_LOCK=y, but it turned out that anon_vma_name() is not
yet compatible with per-VMA locking and assumes mmap_lock to be taken,
which makes the use of per-VMA locking for this API premature.  It was
agreed ([2]) to continue for now with just mmap_lock, but the code
structure is such that it should be easy to add per-VMA locking support
once all the pieces are ready.

One thing that did not change was basing this new API as an ioctl()
command on /proc/<pid>/maps file.  An ioctl-based API on top of pidfd was
considered, but has its own downsides.  Implementing ioctl() directly on
pidfd will cause access permission checks on every single ioctl(), which
leads to performance concerns and potential spam of capable() audit
messages.  It also prevents a nice pattern, possible with
/proc/<pid>/maps, in which application opens /proc/self/maps FD (requiring
no additional capabilities) and passed this FD to profiling agent for
querying.  To achieve similar pattern, a new file would have to be created
from pidf just for VMA querying, which is considered to be inferior to
just querying /proc/<pid>/maps FD as proposed in current approach.  These
aspects were discussed in the hallway track at recent LSF/MM/BPF 2024 and
sticking to procfs ioctl() was the final agreement we arrived at.

  [0] https://github.com/anakryiko/linux/commits/procfs-proc-maps-ioctl-v2/
  [1] https://github.com/libbpf/blazesym/pull/675
  [2] https://lore.kernel.org/bpf/7rm3izyq2vjp5evdjc7c6z4crdd3oerpiknumdnmmemwyiwx7t@hleldw7iozi3/


This patch (of 6):

Extract generic logic to fetch relevant pieces of data to describe VMA
name.  This could be just some string (either special constant or
user-provided), or a string with some formatted wrapping text (e.g.,
"[anon_shmem:<something>]"), or, commonly, file path.  seq_file-based
logic has different methods to handle all three cases, but they are
currently mixed in with extracting underlying sources of data.

This patch splits this into data fetching and data formatting, so that
data fetching can be reused later on.

There should be no functional changes.

Link: https://lkml.kernel.org/r/20240627170900.1672542-1-andrii@kernel.org
Link: https://lkml.kernel.org/r/20240627170900.1672542-2-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-12 15:52:11 -07:00
Kefeng Wang
aca08acce7 fs/proc/task_mmu: use folio API in pte_is_pinned() 
Patch series "mm: remove page_maybe_dma_pinned() and page_mkclean()".

Most page_maybe_dma_pinned() and page_mkclean() callers have been
converted to the folio equivalents, after two more convertsions,
remove them and update the comment and documention.


This patch (of 4):

Convert to use vm_normal_folio() and folio_maybe_dma_pinned() API, which
helps to remove page_maybe_dma_pinned() in the subsequent change.

Link: https://lkml.kernel.org/r/20240604114822.2089819-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20240604114822.2089819-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:17 -07:00
David Hildenbrand
cdd9a571b7 fs/proc: move page_mapcount() to fs/proc/internal.h 
...  and rename it to folio_precise_page_mapcount().  fs/proc is the last
remaining user, and that should stay that way.

While at it, cleanup kpagecount_read() a bit: there are still some legacy
leftovers -- when the interface was introduced it returned the page
refcount, but was changed briefly afterwards to return the page mapcount. 
Further, some simple folio conversion.

Once we stop using the per-page mapcounts of large folios, all
folio_precise_page_mapcount() users will have to implement an alternative
way to achieve what they are trying to achieve, possibly in a less precise
way.

[dan.carpenter@linaro.org: fix uninitialized variable in pagemap_pmd_range()]
  Link: https://lkml.kernel.org/r/9d6eaba7-92f8-4a70-8765-38a519680a87@moroto.mountain
Link: https://lkml.kernel.org/r/20240607122357.115423-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:06 -07:00
David Hildenbrand
3689c3ebdd fs/proc/task_mmu: account non-present entries as "maybe shared, but no idea how often" 
We currently rely on mapcount information for pages referenced by
non-present entries to calculate the USS (shared vs.  private) and the
PSS.

However, relying on mapcounts for non-present entries doesn't make any
sense.  We have to treat such entries as "maybe shared, but no idea how
often", implying that they will *not* get accounted towards the USS, and
will get fully accounted to the PSS (no idea how often shared).

There is one exception: device exclusive entries essentially behave like
present entries (e.g., mapcount incremented).

In smaps_pmd_entry(), use is_pfn_swap_entry() instead of
is_migration_entry(), which should not make a real difference but makes
the code look more similar to the PTE variant.

While at it, adjust the comments in smaps_account().

Link: https://lkml.kernel.org/r/20240607122357.115423-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:06 -07:00
David Hildenbrand
2c1f057e5b fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs 
We added PM_MMAP_EXCLUSIVE in 2015 via commit 77bb499bb6 ("pagemap: add
mmap-exclusive bit for marking pages mapped only here"), when THPs could
not be partially mapped and page_mapcount() returned something that was
true for all pages of the THP.

In 2016, we added support for partially mapping THPs via commit
53f9263bab ("mm: rework mapcount accounting to enable 4k mapping of
THPs") but missed to determine PM_MMAP_EXCLUSIVE as well per page.

Checking page_mapcount() on the head page does not tell the whole story.

We should check each individual page.  In a future without per-page
mapcounts it will be different, but we'll change that to be consistent
with PTE-mapped THPs once we deal with that.

Link: https://lkml.kernel.org/r/20240607122357.115423-4-david@redhat.com
Fixes: 53f9263bab ("mm: rework mapcount accounting to enable 4k mapping of THPs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:05 -07:00
David Hildenbrand
da7f31ed0f fs/proc/task_mmu: don't indicate PM_MMAP_EXCLUSIVE without PM_PRESENT 
Relying on the mapcount for non-present PTEs that reference pages doesn't
make any sense: they are not accounted in the mapcount, so page_mapcount()
== 1 won't return the result we actually want to know.

While we don't check the mapcount for migration entries already, we could
end up checking it for swap, hwpoison, device exclusive, ...  entries,
which we really shouldn't.

There is one exception: device private entries, which we consider
fake-present (e.g., incremented the mapcount).  But we won't care about
that for now for PM_MMAP_EXCLUSIVE, because indicating PM_SWAP for them
although they are fake-present already sounds suspiciously wrong.

Let's never indicate PM_MMAP_EXCLUSIVE without PM_PRESENT.

Link: https://lkml.kernel.org/r/20240607122357.115423-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:05 -07:00
David Hildenbrand
3f9f022e97 fs/proc/task_mmu: indicate PM_FILE for PMD-mapped file THP 
Patch series "fs/proc: move page_mapcount() to fs/proc/internal.h".

With all other page_mapcount() users in the tree gone, move
page_mapcount() to fs/proc/internal.h, rename it and extend the
documentation to prevent future (ab)use.

... of course, I find some issues while working on that code that I sort
first ;)

We'll now only end up calling page_mapcount() [now
folio_precise_page_mapcount()] on pages mapped via present page table
entries.  Except for /proc/kpagecount, that still does questionable
things, but we'll leave that legacy interface as is for now.

Did a quick sanity check.  Likely we would want some better selfestest for
/proc/$/pagemap + smaps.  I'll see if I can find some time to write some
more.


This patch (of 6):

Looks like we never taught pagemap_pmd_range() about the existence of
PMD-mapped file THPs.  Seems to date back to the times when we first added
support for non-anon THPs in the form of shmem THP.

Link: https://lkml.kernel.org/r/20240607122357.115423-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240607122357.115423-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Fixes: 800d8c63b2 ("shmem: add huge pages support")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-07-03 19:30:05 -07:00
Christophe JAILLET
7f07ee5a23
proc: Remove usage of the deprecated ida_simple_xx() API 
ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().

Note that the upper limit of ida_simple_get() is exclusive, but the one of
ida_alloc_max() is inclusive. So a -1 has been added when needed.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/ae10003feb87d240163d0854de95f09e1f00be7d.1717855701.git.christophe.jaillet@wanadoo.fr
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
 2024-06-25 11:15:47 +02:00
Jeff Xu
399ab86ea5 /proc/pid/smaps: add mseal info for vma 
Add sl in /proc/pid/smaps to indicate vma is sealed

Link: https://lkml.kernel.org/r/20240614232014.806352-2-jeffxu@google.com
Fixes: 8be7258aad ("mseal: add mseal syscall")
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Röttger <sroettger@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-06-24 20:52:09 -07:00
Joel Granados
acc154691f sysctl: Warn on an empty procname element 
Add a pr_err warning in case a ctl_table is registered with a sentinel
element containing a NULL procname.

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Joel Granados
3717540377 sysctl: Remove ctl_table sentinel code comments 
Remove the mention of a "zero terminated entry" from the
__register_sysctl_table function doc.

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Joel Granados
a02fe70de4 sysctl: Remove "child" sysctl code comments 
Erase the code comments mentioning "child" that were forgotten when the
child element was removed in commit 2f2665c13a ("sysctl: replace
child with an enumeration").

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Joel Granados
aef9d25e7f sysctl: Remove superfluous empty allocations from sysctl internals 
Now that the sentinels have been removed from ctl_table arrays, there is
no need to artificially append empty ctl_table elements at ctl_table
registration. Remove superfluous empty allocation from new_dir and
new_links.

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Joel Granados
55bb7eb62d sysctl: Replace nr_entries with ctl_table_size in new_links 
The number of ctl_table entries (nr_entries) calculation was previously
based on the ctl_table_size and the sentinel element. Since the
sentinels have been removed, we remove the calculation and just use the
ctl_table_size from the ctl_table_header.

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Joel Granados
d7a76ec871 sysctl: Remove check for sentinel element in ctl_table arrays 
Use ARRAY_SIZE exclusively by removing the check to ->procname in the
stopping criteria of the loops traversing ctl_table arrays. This commit
finalizes the removal of the sentinel elements at the end of ctl_table
arrays which reduces the build time size and run time memory bloat by
~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove the entry->procname evaluation from the for loop stopping
criteria in sysctl and sysctl_net.

Signed-off-by: Joel Granados <j.granados@samsung.com>
 2024-06-13 10:50:52 +02:00
Chengming Zhou
c2dc78b86e mm/ksm: fix ksm_zero_pages accounting 
We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.

So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.

Fix it by changing to use atomic_long_t, and the same case with the
mm->ksm_zero_pages.

Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e0 ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f07 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2024-06-05 19:19:26 -07:00