leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
mainlining shenanigans
933,048 Commits 2 Branches 0 Tags 5.1 GiB
C 97.7%
Assembly 1.1%
Shell 0.4%
Makefile 0.3%
Python 0.2%
Other 0.1%
909adfc66b
Go to file
Nicholas Piggin 909adfc66b powerpc/64s/hash: Fix hash_preload running with interrupts enabled 
Commit 2f92447f9f ("powerpc/book3s64/hash: Use the pte_t address from the
caller") removed the local_irq_disable from hash_preload, but it was
required for more than just the page table walk: the hash pte busy bit is
effectively a lock which may be taken in interrupt context, and the local
update flag test must not be preempted before it's used.

This solves apparent lockups with perf interrupting __hash_page_64K. If
get_perf_callchain then also takes a hash fault on the same page while it
is already locked, it will loop forever taking hash faults, which looks like
this:

  cpu 0x49e: Vector: 100 (System Reset) at [c00000001a4f7d70]
      pc: c000000000072dc8: hash_page_mm+0x8/0x800
      lr: c00000000000c5a4: do_hash_page+0x24/0x38
      sp: c0002ac1cc69ac70
     msr: 8000000000081033
    current = 0xc0002ac1cc602e00
    paca    = 0xc00000001de1f280   irqmask: 0x03   irq_happened: 0x01
      pid   = 20118, comm = pread2_processe
  Linux version 5.8.0-rc6-00345-g1fad14f18bc6
  49e:mon> t
  [c0002ac1cc69ac70] c00000000000c5a4 do_hash_page+0x24/0x38 (unreliable)
  --- Exception: 300 (Data Access) at c00000000008fa60 __copy_tofrom_user_power7+0x20c/0x7ac
  [link register   ] c000000000335d10 copy_from_user_nofault+0xf0/0x150
  [c0002ac1cc69af70] c00032bf9fa3c880 (unreliable)
  [c0002ac1cc69afa0] c000000000109df0 read_user_stack_64+0x70/0xf0
  [c0002ac1cc69afd0] c000000000109fcc perf_callchain_user_64+0x15c/0x410
  [c0002ac1cc69b060] c000000000109c00 perf_callchain_user+0x20/0x40
  [c0002ac1cc69b080] c00000000031c6cc get_perf_callchain+0x25c/0x360
  [c0002ac1cc69b120] c000000000316b50 perf_callchain+0x70/0xa0
  [c0002ac1cc69b140] c000000000316ddc perf_prepare_sample+0x25c/0x790
  [c0002ac1cc69b1a0] c000000000317350 perf_event_output_forward+0x40/0xb0
  [c0002ac1cc69b220] c000000000306138 __perf_event_overflow+0x88/0x1a0
  [c0002ac1cc69b270] c00000000010cf70 record_and_restart+0x230/0x750
  [c0002ac1cc69b620] c00000000010d69c perf_event_interrupt+0x20c/0x510
  [c0002ac1cc69b730] c000000000027d9c performance_monitor_exception+0x4c/0x60
  [c0002ac1cc69b750] c00000000000b2f8 performance_monitor_common_virt+0x1b8/0x1c0
  --- Exception: f00 (Performance Monitor) at c0000000000cb5b0 pSeries_lpar_hpte_insert+0x0/0x160
  [link register   ] c0000000000846f0 __hash_page_64K+0x210/0x540
  [c0002ac1cc69ba50] 0000000000000000 (unreliable)
  [c0002ac1cc69bb00] c000000000073ae0 update_mmu_cache+0x390/0x3a0
  [c0002ac1cc69bb70] c00000000037f024 wp_page_copy+0x364/0xce0
  [c0002ac1cc69bc20] c00000000038272c do_wp_page+0xdc/0xa60
  [c0002ac1cc69bc70] c0000000003857bc handle_mm_fault+0xb9c/0x1b60
  [c0002ac1cc69bd50] c00000000006c434 __do_page_fault+0x314/0xc90
  [c0002ac1cc69be20] c00000000000c5c8 handle_page_fault+0x10/0x2c
  --- Exception: 300 (Data Access) at 00007fff8c861fe8
  SP (7ffff6b19660) is in userspace

Fixes: 2f92447f9f ("powerpc/book3s64/hash: Use the pte_t address from the caller")
Reported-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reported-by: Anton Blanchard <anton@ozlabs.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200727060947.10060-1-npiggin@gmail.com
2020-07-27 17:02:09 +10:00
arch powerpc/64s/hash: Fix hash_preload running with interrupts enabled 2020-07-27 17:02:09 +10:00
block block-5.8-2020-06-19 2020-06-19 13:11:26 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: drbg - always try to free Jitter RNG instance 2020-06-15 17:38:54 +10:00
Documentation powerpc/vas: Report proper error code for address translation failure 2020-07-15 23:09:55 +10:00
drivers Pin control fixes for the v5.8 cycle, first take: 2020-06-21 13:04:57 -07:00
fs A few fixes and small cleanups for tracing: 2020-06-20 13:17:47 -07:00
include powerpc fixes for 5.8 #3 2020-06-21 10:02:53 -07:00
init Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel A few fixes and small cleanups for tracing: 2020-06-20 13:17:47 -07:00
lib Kbuild fixes for v5.8 2020-06-21 12:44:52 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm powerpc fixes for 5.8 #3 2020-06-21 10:02:53 -07:00
net An important follow-up for replica reads support that went into -rc1 2020-06-19 12:25:04 -07:00
samples Kbuild fixes for v5.8 2020-06-21 12:44:52 -07:00
scripts Kbuild fixes for v5.8 2020-06-21 12:44:52 -07:00
security selinux/stable-5.8 PR 20200621 2020-06-21 15:41:24 -07:00
sound ASoC: SOF: Replace zero-length array with flexible-array 2020-06-15 23:08:32 -05:00
tools selftests/powerpc: Use proper error code to check fault address 2020-07-15 23:10:17 +10:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt MIPS: 2020-06-12 11:05:52 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: generate vmlinux.symvers and reuse it for the second modpost 2020-06-06 23:38:12 +09:00
.mailmap A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2020-06-20 19:18:27 -07:00
Makefile Linux 5.8-rc2 2020-06-21 15:45:29 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.