Pull irq fixes from Thomas Gleixner:
"A set of irqchip updates:
- Make the GENERIC_IRQ_MULTI_HANDLER configuration correct
- Add a missing DT compatible string for the Ingenic driver
- Remove the pointless debugfs_file pointer from struct irqdomain"
* tag 'irq-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/ingenic: Add support for the JZ4760
dt-bindings/irq: Add compatible string for the JZ4760B
irqchip: Do not blindly select CONFIG_GENERIC_IRQ_MULTI_HANDLER
ARM: ep93xx: Select GENERIC_IRQ_MULTI_HANDLER directly
irqdomain: Remove debugfs_file from struct irq_domain
Pull timer fix from Thomas Gleixner:
"A single fix in for hrtimers to prevent an interrupt storm caused by
the lack of reevaluation of the timers which expire in softirq context
under certain circumstances, e.g. when the clock was set"
* tag 'timers-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hrtimer: Update softirq_expires_next correctly after __hrtimer_get_next_event()
Pull scheduler fixes from Thomas Gleixner:
"A set of scheduler updates:
- Prevent a NULL pointer dereference in the migration_stop_cpu()
mechanims
- Prevent self concurrency of affine_move_task()
- Small fixes and cleanups related to task migration/affinity setting
- Ensure that sync_runqueues_membarrier_state() is invoked on the
current CPU when it is in the cpu mask"
* tag 'sched-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/membarrier: fix missing local execution of ipi_sync_rq_state()
sched: Simplify set_affinity_pending refcounts
sched: Fix affine_move_task() self-concurrency
sched: Optimize migration_cpu_stop()
sched: Collate affine_move_task() stoppers
sched: Simplify migration_cpu_stop()
sched: Fix migration_cpu_stop() requeueing
Pull locking fixes from Thomas Gleixner:
"A couple of locking fixes:
- A fix for the static_call mechanism so it handles unaligned
addresses correctly.
- Make u64_stats_init() a macro so every instance gets a seperate
lockdep key.
- Make seqcount_latch_init() a macro as well to preserve the static
variable which is used for the lockdep key"
* tag 'locking-urgent-2021-03-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
seqlock,lockdep: Fix seqcount_latch_init()
u64_stats,lockdep: Fix u64_stats_init() vs lockdep
static_call: Fix the module key fixup
Pull perf fixes from Borislav Petkov:
- Make sure PMU internal buffers are flushed for per-CPU events too and
properly handle PID/TID for large PEBS.
- Handle the case properly when there's no PMU and therefore return an
empty list of perf MSRs for VMX to switch instead of reading random
garbage from the stack.
* tag 'perf_urgent_for_v5.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/perf: Use RET0 as default for guest_get_msrs to handle "no PMU" case
perf/x86/intel: Set PERF_ATTACH_SCHED_CB for large PEBS and LBR
perf/core: Flush PMU internal buffers for per-CPU events
Merge misc fixes from Andrew Morton:
"28 patches.
Subsystems affected by this series: mm (memblock, pagealloc, hugetlb,
highmem, kfence, oom-kill, madvise, kasan, userfaultfd, memcg, and
zram), core-kernel, kconfig, fork, binfmt, MAINTAINERS, kbuild, and
ia64"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (28 commits)
zram: fix broken page writeback
zram: fix return value on writeback_store
mm/memcg: set memcg when splitting page
mm/memcg: rename mem_cgroup_split_huge_fixup to split_page_memcg and add nr_pages argument
ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign
ia64: fix ia64_syscall_get_set_arguments() for break-based syscalls
mm/userfaultfd: fix memory corruption due to writeprotect
kasan: fix KASAN_STACK dependency for HW_TAGS
kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC
mm/madvise: replace ptrace attach requirement for process_madvise
include/linux/sched/mm.h: use rcu_dereference in in_vfork()
kfence: fix reports if constant function prefixes exist
kfence, slab: fix cache_alloc_debugcheck_after() for bulk allocations
kfence: fix printk format for ptrdiff_t
linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
MAINTAINERS: exclude uapi directories in API/ABI section
binfmt_misc: fix possible deadlock in bm_register_write
mm/highmem.c: fix zero_user_segments() with start > end
hugetlb: do early cow when page pinned on src mm
mm: use is_cow_mapping() across tree where proper
...
With the freezer using the proper signaling to notify us of when it's
time to freeze a thread, we can re-enable normal freezer usage for the
IO threads. Ensure that SQPOLL, io-wq, and the io-wq manager call
try_to_freeze() appropriately, and remove the default setting of
PF_NOFREEZE from create_io_thread().
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't send fake signals to PF_IO_WORKER threads, they don't accept
signals. Just treat them like kthreads in this regard, all they need
is a wakeup as no forced kernel/user transition is needed.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Remove the list parameter from the function call since the exit filter
list is the only remaining list used by this function.
This cleans up commit 5260ecc2e0
("audit: deprecate the AUDIT_FILTER_ENTRY filter")
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Pull io_uring fixes from Jens Axboe:
"Not quite as small this week as I had hoped, but at least this should
be the end of it. All the little known issues have been ironed out -
most of it little stuff, but cancelations being the bigger part. Only
minor tweaks and/or regular fixes expected beyond this point.
- Fix the creds tracking for async (io-wq and SQPOLL)
- Various SQPOLL fixes related to parking, sharing, forking, IOPOLL,
completions, and life times. Much simpler now.
- Make IO threads unfreezable by default, on account of a bug report
that had them spinning on resume. Honestly not quite sure why
thawing leaves us with a perpetual signal pending (causing the
spin), but for now make them unfreezable like there were in 5.11
and prior.
- Move personality_idr to xarray, solving a use-after-free related to
removing an entry from the iterator callback. Buffer idr needs the
same treatment.
- Re-org around and task vs context tracking, enabling the fixing of
cancelations, and then cancelation fixes on top.
- Various little bits of cleanups and hardening, and removal of now
dead parts"
* tag 'io_uring-5.12-2021-03-12' of git://git.kernel.dk/linux-block: (34 commits)
io_uring: fix OP_ASYNC_CANCEL across tasks
io_uring: cancel sqpoll via task_work
io_uring: prevent racy sqd->thread checks
io_uring: remove useless ->startup completion
io_uring: cancel deferred requests in try_cancel
io_uring: perform IOPOLL reaping if canceler is thread itself
io_uring: force creation of separate context for ATTACH_WQ and non-threads
io_uring: remove indirect ctx into sqo injection
io_uring: fix invalid ctx->sq_thread_idle
kernel: make IO threads unfreezable by default
io_uring: always wait for sqd exited when stopping SQPOLL thread
io_uring: remove unneeded variable 'ret'
io_uring: move all io_kiocb init early in io_init_req()
io-wq: fix ref leak for req in case of exit cancelations
io_uring: fix complete_post races for linked req
io_uring: add io_disarm_next() helper
io_uring: fix io_sq_offload_create error handling
io-wq: remove unused 'user' member of io_wq
io_uring: Convert personality_idr to XArray
io_uring: clean R_DISABLED startup mess
...
A small cleanup that allows for fixup_pi_state_owner() only to be called
from fixup_owner(), and make requeue_pi uniformly call fixup_owner()
regardless of the state in which the fixup is actually needed. Of course
this makes the caller's first pi_state->owner != current check redundant,
but that should't really matter.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210226175029.50335-2-dave@stgolabs.net
Update wake_futex_pi() and kill the call altogether. This is possible because:
(i) The case of fixup_owner() in which the pi_mutex was stolen from the
signaled enqueued top-waiter which fails to trylock and doesn't see a
current owner of the rtmutex but needs to acknowledge an non-enqueued
higher priority waiter, which is the other alternative. This used to be
handled by rt_mutex_next_owner(), which guaranteed fixup_pi_state_owner('newowner')
never to be nil. Nowadays the logic is handled by an EAGAIN loop, without
the need of rt_mutex_next_owner(). Specifically:
c1e2f0eaf0 (futex: Avoid violating the 10th rule of futex)
9f5d1c336a (futex: Handle transient "ownerless" rtmutex state correctly)
(ii) rt_mutex_next_owner() and rt_mutex_top_waiter() are semantically
equivalent, as of:
c28d62cf52 (locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter())
So instead of keeping the call around, just use the good ole rt_mutex_top_waiter().
No change in semantics.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210226175029.50335-1-dave@stgolabs.net
Daniel Borkmann says:
====================
pull-request: bpf 2021-03-10
The following pull-request contains BPF updates for your *net* tree.
We've added 8 non-merge commits during the last 5 day(s) which contain
a total of 11 files changed, 136 insertions(+), 17 deletions(-).
The main changes are:
1) Reject bogus use of vmlinux BTF as map/prog creation BTF, from Alexei Starovoitov.
2) Fix allocation failure splat in x86 JIT for large progs. Also fix overwriting
percpu cgroup storage from tracing programs when nested, from Yonghong Song.
3) Fix rx queue retrieval in XDP for multi-queue veth, from Maciej Fijalkowski.
4) Fix bpf_check_mtu() helper API before freeze to have mtu_len as custom skb/xdp
L3 input length, from Jesper Dangaard Brouer.
5) Fix inode_storage's lookup_elem return value upon having bad fd, from Tal Lossos.
6) Fix bpftool and libbpf cross-build on MacOS, from Georgi Valkov.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The io-wq threads were already marked as no-freeze, but the manager was
not. On resume, we perpetually have signal_pending() being true, and
hence the manager will loop and spin 100% of the time.
Just mark the tasks created by create_io_thread() as PF_NOFREEZE by
default, and remove any knowledge of it in io-wq and io_uring.
Reported-by: Kevin Locke <kevin@kevinlocke.name>
Tested-by: Kevin Locke <kevin@kevinlocke.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A significant portion of __calc_delta() time is spent in the loop
shifting a u64 by 32 bits. Use `fls` instead of iterating.
This is ~7x faster on benchmarks.
The generic `fls` implementation (`generic_fls`) is still ~4x faster
than the loop.
Architectures that have a better implementation will make use of it. For
example, on x86 we get an additional factor 2 in speed without dedicated
implementation.
On GCC, the asm versions of `fls` are about the same speed as the
builtin. On Clang, the versions that use fls are more than twice as
slow as the builtin. This is because the way the `fls` function is
written, clang puts the value in memory:
https://godbolt.org/z/EfMbYe. This bug is filed at
https://bugs.llvm.org/show_bug.cgi?idI406.
```
name cpu/op
BM_Calc<__calc_delta_loop> 9.57ms Â=B112%
BM_Calc<__calc_delta_generic_fls> 2.36ms Â=B113%
BM_Calc<__calc_delta_asm_fls> 2.45ms Â=B113%
BM_Calc<__calc_delta_asm_fls_nomem> 1.66ms Â=B112%
BM_Calc<__calc_delta_asm_fls64> 2.46ms Â=B113%
BM_Calc<__calc_delta_asm_fls64_nomem> 1.34ms Â=B115%
BM_Calc<__calc_delta_builtin> 1.32ms Â=B111%
```
Signed-off-by: Clement Courbet <courbet@google.com>
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210303224653.2579656-1-joshdon@google.com
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-03-09
The following pull-request contains BPF updates for your *net-next* tree.
We've added 90 non-merge commits during the last 17 day(s) which contain
a total of 114 files changed, 5158 insertions(+), 1288 deletions(-).
The main changes are:
1) Faster bpf_redirect_map(), from Björn.
2) skmsg cleanup, from Cong.
3) Support for floating point types in BTF, from Ilya.
4) Documentation for sys_bpf commands, from Joe.
5) Support for sk_lookup in bpf_prog_test_run, form Lorenz.
6) Enable task local storage for tracing programs, from Song.
7) bpf_for_each_map_elem() helper, from Yonghong.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull networking fixes from David Miller:
1) Fix transmissions in dynamic SMPS mode in ath9k, from Felix Fietkau.
2) TX skb error handling fix in mt76 driver, also from Felix.
3) Fix BPF_FETCH atomic in x86 JIT, from Brendan Jackman.
4) Avoid double free of percpu pointers when freeing a cloned bpf prog.
From Cong Wang.
5) Use correct printf format for dma_addr_t in ath11k, from Geert
Uytterhoeven.
6) Fix resolve_btfids build with older toolchains, from Kun-Chuan
Hsieh.
7) Don't report truncated frames to mac80211 in mt76 driver, from
Lorenzop Bianconi.
8) Fix watcdog timeout on suspend/resume of stmmac, from Joakim Zhang.
9) mscc ocelot needs NET_DEVLINK selct in Kconfig, from Arnd Bergmann.
10) Fix sign comparison bug in TCP_ZEROCOPY_RECEIVE getsockopt(), from
Arjun Roy.
11) Ignore routes with deleted nexthop object in mlxsw, from Ido
Schimmel.
12) Need to undo tcp early demux lookup sometimes in nf_nat, from
Florian Westphal.
13) Fix gro aggregation for udp encaps with zero csum, from Daniel
Borkmann.
14) Make sure to always use imp*_ndo_send when necessaey, from Jason A.
Donenfeld.
15) Fix TRSCER masks in sh_eth driver from Sergey Shtylyov.
16) prevent overly huge skb allocationsd in qrtr, from Pavel Skripkin.
17) Prevent rx ring copnsumer index loss of sync in enetc, from Vladimir
Oltean.
18) Make sure textsearch copntrol block is large enough, from Wilem de
Bruijn.
19) Revert MAC changes to r8152 leading to instability, from Hates Wang.
20) Advance iov in 9p even for empty reads, from Jissheng Zhang.
21) Double hook unregister in nftables, from PabloNeira Ayuso.
22) Fix memleak in ixgbe, fropm Dinghao Liu.
23) Avoid dups in pkt scheduler class dumps, from Maximilian Heyne.
24) Various mptcp fixes from Florian Westphal, Paolo Abeni, and Geliang
Tang.
25) Fix DOI refcount bugs in cipso, from Paul Moore.
26) One too many irqsave in ibmvnic, from Junlin Yang.
27) Fix infinite loop with MPLS gso segmenting via virtio_net, from
Balazs Nemeth.
* git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net: (164 commits)
s390/qeth: fix notification for pending buffers during teardown
s390/qeth: schedule TX NAPI on QAOB completion
s390/qeth: improve completion of pending TX buffers
s390/qeth: fix memory leak after failed TX Buffer allocation
net: avoid infinite loop in mpls_gso_segment when mpls_hlen == 0
net: check if protocol extracted by virtio_net_hdr_set_proto is correct
net: dsa: xrs700x: check if partner is same as port in hsr join
net: lapbether: Remove netif_start_queue / netif_stop_queue
atm: idt77252: fix null-ptr-dereference
atm: uPD98402: fix incorrect allocation
atm: fix a typo in the struct description
net: qrtr: fix error return code of qrtr_sendmsg()
mptcp: fix length of ADD_ADDR with port sub-option
net: bonding: fix error return code of bond_neigh_init()
net: enetc: allow hardware timestamping on TX queues with tc-etf enabled
net: enetc: set MAC RX FIFO to recommended value
net: davicom: Use platform_get_irq_optional()
net: davicom: Fix regulator not turned off on driver removal
net: davicom: Fix regulator not turned off on failed probe
net: dsa: fix switchdev objects on bridge master mistakenly being applied on ports
...
The XDP_REDIRECT implementations for maps and non-maps are fairly
similar, but obviously need to take different code paths depending on
if the target is using a map or not. Today, the redirect targets for
XDP either uses a map, or is based on ifindex.
Here, the map type and id are added to bpf_redirect_info, instead of
the actual map. Map type, map item/ifindex, and the map_id (if any) is
passed to xdp_do_redirect().
For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper,
a special map type/id are used. Map type of UNSPEC together with map id
equal to INT_MAX has the special meaning of an ifindex based
redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive
([1,INT_MAX[).
In addition to making the code easier to follow, using explicit type
and id in bpf_redirect_info has a slight positive performance impact
by avoiding a pointer indirection for the map type lookup, and instead
use the cacheline for bpf_redirect_info.
Since the actual map is not passed via bpf_redirect_info anymore, the
map lookup is only done in the BPF helper. This means that the
bpf_clear_redirect_map() function can be removed. The actual map item
is RCU protected.
The bpf_redirect_info flags member is not used by XDP, and not
read/written any more. The map member is only written to when
required/used, and not unconditionally.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com
Currently the bpf_redirect_map() implementation dispatches to the
correct map-lookup function via a switch-statement. To avoid the
dispatching, this change adds bpf_redirect_map() as a map
operation. Each map provides its bpf_redirect_map() version, and
correct function is automatically selected by the BPF verifier.
A nice side-effect of the code movement is that the map lookup
functions are now local to the map implementation files, which removes
one additional function call.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com
Adds missing license and/or copyright headers for KCSAN source files.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Since KUnit now support parameterized tests via KUNIT_CASE_PARAM, update
KCSAN's test to switch to it for parameterized tests. This simplifies
parameterized tests and gets rid of the "parameters in case name"
workaround (hack).
At the same time, we can increase the maximum number of threads used,
because on systems with too few CPUs, KUnit allows us to now stop at the
maximum useful threads and not unnecessarily execute redundant test
cases with (the same) limited threads as had been the case before.
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Per recently added KUnit style recommendations at
Documentation/dev-tools/kunit/style.rst, make the following changes to
the KCSAN test:
1. Rename 'kcsan-test.c' to 'kcsan_test.c'.
2. Rename suite name 'kcsan-test' to 'kcsan'.
3. Rename CONFIG_KCSAN_TEST to CONFIG_KCSAN_KUNIT_TEST and
default to KUNIT_ALL_TESTS.
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Commit 56348560d4 ("debugfs: do not attempt to create a new file
before the filesystem is initalized") forbids creating new debugfs files
until debugfs is fully initialized. This means that KCSAN's debugfs
file creation, which happened at the end of __init(), no longer works.
And was apparently never supposed to work!
However, there is no reason to create KCSAN's debugfs file so early.
This commit therefore moves its creation to a late_initcall() callback.
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: stable <stable@vger.kernel.org>
Fixes: 56348560d4 ("debugfs: do not attempt to create a new file before the filesystem is initalized")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit replaces a hard-coded "rcu_torture_stall" string in a
pr_alert() format with "%s" and __func__.
Signed-off-by: Stephen Zhang <stephenzhangzsd@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit replaces a hard-coded "torture_init_begin" string in
a pr_alert() format with "%s" and __func__.
Signed-off-by: Stephen Zhang <stephenzhangzsd@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a block comment that gives a high-level overview of
how RCU tasks trace grace periods progress. It also adds a note about
how exiting tasks are handled, plus it gives an overview of the memory
ordering.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
[ paulmck: Fix commit log per Mathieu Desnoyers feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The command 'find ./kernel/rcu/ | xargs ./scripts/kernel-doc -none'
reported an issue with the kernel-doc of struct rcu_tasks.
This commit rectifies the kernel-doc, such that no issues remain for
./kernel/rcu/.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In kernels built with CONFIG_RCU_STRICT_GRACE_PERIOD=y, every grace
period is an expedited grace period. However, rcu_read_unlock_special()
does not treat them that way, instead allowing the deferred quiescent
state to be reported whenever. This commit therefore adds a check of
this Kconfig option that causes rcu_read_unlock_special() to treat all
grace periods as expedited for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, rcutorture refuses to test RCU priority boosting in
CONFIG_HOTPLUG_CPU=y kernels, which are the only kind normally built on
x86 these days. This commit therefore updates rcutorture's tests of RCU
priority boosting to make them safe for CPU hotplug. However, these tests
will fail unless TIMER_SOFTIRQ runs at realtime priority, which does not
happen in current mainline. This commit therefore also refuses to test
RCU priority boosting except in kernels built with CONFIG_PREEMPT_RT=y.
While in the area, this commt adds some debug output at boost-fail time
that helps diagnose the cause of the failure, for example, failing to
run TIMER_SOFTIRQ at realtime priority.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Scott Wood <swood@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Historically, a task that has been subjected to RCU priority boosting is
deboosted at rcu_read_unlock() time. However, with the advent of deferred
quiescent states, if the outermost rcu_read_unlock() was invoked with
either bottom halves, interrupts, or preemption disabled, the deboosting
will be delayed for some time. During this time, a low-priority process
might be incorrectly running at a high real-time priority level.
Fortunately, rcu_read_unlock_special() already provides mechanisms for
forcing a minimal deferral of quiescent states, at least for kernels
built with CONFIG_IRQ_WORK=y. These mechanisms are currently used
when expedited grace periods are pending that might be blocked by the
current task. This commit therefore causes those mechanisms to also be
used in cases where the current task has been or might soon be subjected
to RCU priority boosting. Note that this applies to all kernels built
with CONFIG_RCU_BOOST=y, regardless of whether or not they are also
built with CONFIG_PREEMPT_RT=y.
This approach assumes that kernels build for use with aggressive real-time
applications are built with CONFIG_IRQ_WORK=y. It is likely to be far
simpler to enable CONFIG_IRQ_WORK=y than to implement a fast-deboosting
scheme that works correctly in its absence.
While in the area, alphabetize the rcu_preempt_deferred_qs_handler()
function's local variables.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Scott Wood <swood@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The name nocb_gp_update_state() is unenlightening, so this commit changes
it to nocb_gp_update_state_deoffloading(). This function now does what
its name says, updates state and returns true if the CPU corresponding to
the specified rcu_data structure is in the process of being de-offloaded.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
At the start of a CPU-hotplug operation, the incoming CPU's callback
list can be in a number of states:
1. Disabled and empty. This is the case when the boot CPU has
not invoked call_rcu(), when a non-boot CPU first comes online,
and when a non-offloaded CPU comes back online. In this case,
it is both necessary and permissible to initialize ->cblist.
Because either the CPU is currently running with interrupts
disabled (boot CPU) or is not yet running at all (other CPUs),
it is not necessary to acquire ->nocb_lock.
In this case, initialization is required.
2. Disabled and non-empty. This cannot occur, because early boot
call_rcu() invocations enable the callback list before enqueuing
their callback.
3. Enabled, whether empty or not. In this case, the callback
list has already been initialized. This case occurs when the
boot CPU has executed an early boot call_rcu() and also when
an offloaded CPU comes back online. In both cases, there is
no need to initialize the callback list: In the boot-CPU case,
the CPU has not (yet) gone offline, and in the offloaded case,
the rcuo kthreads are taking care of business.
Because it is not necessary to initialize the callback list,
it is also not necessary to acquire ->nocb_lock.
Therefore, checking if the segcblist is enabled suffices. This commit
therefore initializes the callback list at rcutree_prepare_cpu() time
only if that list is disabled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The nocb_cb_wait() function first sets the rdp->nocb_cb_sleep flag to
true by after invoking the callbacks, and then sets it back to false if
it finds more callbacks that are ready to invoke.
This is confusing and will become unsafe if this flag is ever read
locklessly. This commit therefore writes it only once, based on the
state after both callback invocation and checking.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
It makes no sense to de-offload an offline CPU because that CPU will never
invoke any remaining callbacks. It also makes little sense to offload an
offline CPU because any pending RCU callbacks were migrated when that CPU
went offline. Yes, it is in theory possible to use a number of tricks
to permit offloading and deoffloading offline CPUs in certain cases, but
in practice it is far better to have the simple and deterministic rule
"Toggling the offload state of an offline CPU is forbidden".
For but one example, consider that an offloaded offline CPU might have
millions of callbacks queued. Best to just say "no".
This commit therefore forbids toggling of the offloaded state of
offline CPUs.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Provide CONFIG_PROVE_RCU sanity checks to ensure we are always reading
the offloaded state of an rdp in a safe and stable way and prevent from
its value to be changed under us. We must either hold the barrier mutex,
the cpu-hotplug lock (read or write) or the nocb lock.
Local non-preemptible reads are also safe. NOCB kthreads and timers have
their own means of synchronization against the offloaded state updaters.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a few crude tests for mem_dump_obj() to rcutorture
runs. Just to prevent bitrot, you understand!
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The single-argument variant of kfree_rcu() is currently not
tested by any member of the rcutoture test suite. This
commit therefore adds rcuscale code to test it. This
testing is controlled by two new boolean module parameters,
kfree_rcu_test_single and kfree_rcu_test_double. If one
is set and the other not, only the corresponding variant
is tested, otherwise both are tested, with the variant to
be tested determined randomly on each invocation.
Both of these module parameters are initialized to false,
so setting either to true will test only that variant.
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Running an rcuscale stress-suite can lead to "Out of memory" of a
system. This can happen under high memory pressure with a small amount
of physical memory.
For example, a KVM test configuration with 64 CPUs and 512 megabytes
can result in OOM when running rcuscale with below parameters:
../kvm.sh --torture rcuscale --allcpus --duration 10 --kconfig CONFIG_NR_CPUS=64 \
--bootargs "rcuscale.kfree_rcu_test=1 rcuscale.kfree_nthreads=16 rcuscale.holdoff=20 \
rcuscale.kfree_loops=10000 torture.disable_onoff_at_boot" --trust-make
<snip>
[ 12.054448] kworker/1:1H invoked oom-killer: gfp_mask=0x2cc0(GFP_KERNEL|__GFP_NOWARN), order=0, oom_score_adj=0
[ 12.055303] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510
[ 12.055416] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
[ 12.056485] Workqueue: events_highpri fill_page_cache_func
[ 12.056485] Call Trace:
[ 12.056485] dump_stack+0x57/0x6a
[ 12.056485] dump_header+0x4c/0x30a
[ 12.056485] ? del_timer_sync+0x20/0x30
[ 12.056485] out_of_memory.cold.47+0xa/0x7e
[ 12.056485] __alloc_pages_slowpath.constprop.123+0x82f/0xc00
[ 12.056485] __alloc_pages_nodemask+0x289/0x2c0
[ 12.056485] __get_free_pages+0x8/0x30
[ 12.056485] fill_page_cache_func+0x39/0xb0
[ 12.056485] process_one_work+0x1ed/0x3b0
[ 12.056485] ? process_one_work+0x3b0/0x3b0
[ 12.060485] worker_thread+0x28/0x3c0
[ 12.060485] ? process_one_work+0x3b0/0x3b0
[ 12.060485] kthread+0x138/0x160
[ 12.060485] ? kthread_park+0x80/0x80
[ 12.060485] ret_from_fork+0x22/0x30
[ 12.062156] Mem-Info:
[ 12.062350] active_anon:0 inactive_anon:0 isolated_anon:0
[ 12.062350] active_file:0 inactive_file:0 isolated_file:0
[ 12.062350] unevictable:0 dirty:0 writeback:0
[ 12.062350] slab_reclaimable:2797 slab_unreclaimable:80920
[ 12.062350] mapped:1 shmem:2 pagetables:8 bounce:0
[ 12.062350] free:10488 free_pcp:1227 free_cma:0
...
[ 12.101610] Out of memory and no killable processes...
[ 12.102042] Kernel panic - not syncing: System is deadlocked on memory
[ 12.102583] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510
[ 12.102600] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
<snip>
Because kvfree_rcu() has a fallback path, memory allocation failure is
not the end of the world. Furthermore, the added overhead of aggressive
GFP settings must be balanced against the overhead of the fallback path,
which is a cache miss for double-argument kvfree_rcu() and a call to
synchronize_rcu() for single-argument kvfree_rcu(). The current choice
of GFP_KERNEL|__GFP_NOWARN can result in longer latencies than a call
to synchronize_rcu(), so less-tenacious GFP flags would be helpful.
Here is the tradeoff that must be balanced:
a) Minimize use of the fallback path,
b) Avoid pushing the system into OOM,
c) Bound allocation latency to that of synchronize_rcu(), and
d) Leave the emergency reserves to use cases lacking fallbacks.
This commit therefore changes GFP flags from GFP_KERNEL|__GFP_NOWARN to
GFP_KERNEL|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_NOWARN. This combination
leaves the emergency reserves alone and can initiate reclaim, but will
not invoke the OOM killer.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
__GFP_RETRY_MAYFAIL can spend quite a bit of time reclaiming, and this
can be wasted effort given that there is a fallback code path in case
memory allocation fails.
__GFP_NORETRY does perform some light-weight reclaim, but it will fail
under OOM conditions, allowing the fallback to be taken as an alternative
to hard-OOMing the system.
There is a four-way tradeoff that must be balanced:
1) Minimize use of the fallback path;
2) Avoid full-up OOM;
3) Do a light-wait allocation request;
4) Avoid dipping into the emergency reserves.
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The krc_this_cpu_unlock() function does a raw_spin_unlock() immediately
followed by a local_irq_restore(). This commit saves a line of code by
merging them into a raw_spin_unlock_irqrestore(). This transformation
also reduces scheduling latency because raw_spin_unlock_irqrestore()
responds immediately to a reschedule request. In contrast,
local_irq_restore() does a scheduling-oblivious enabling of interrupts.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit applies the __GFP_NOMEMALLOC gfp flag to memory allocations
carried out by the single-argument variant of kvfree_rcu(), thus avoiding
this can-sleep code path from dipping into the emergency reserves.
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Single-argument kvfree_rcu() must be invoked from sleepable contexts,
so we can directly allocate pages. Furthermmore, the fallback in case
of page-allocation failure is the high-latency synchronize_rcu(), so it
makes sense to do these page allocations from the fastpath, and even to
permit limited sleeping within the allocator.
This commit therefore allocates if needed on the fastpath using
GFP_KERNEL|__GFP_RETRY_MAYFAIL. This also has the beneficial effect
of leaving kvfree_rcu()'s per-CPU caches to the double-argument variant
of kvfree_rcu(), given that the double-argument variant cannot directly
invoke the allocator.
[ paulmck: Add add_ptr_to_bulk_krc_lock header comment per Michal Hocko. ]
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In rcu_nmi_enter(), there is an erroneous instrumentation_end() in the
second branch of the "if" statement. Oddly enough, "objtool check -f
vmlinux.o" fails to complain because it is unable to correctly cover
all cases. Instead, objtool visits the third branch first, which marks
following trace_rcu_dyntick() as visited. This commit therefore removes
the spurious instrumentation_end().
Fixes: 04b25a495b ("rcu: Mark rcu_nmi_enter() call to rcu_cleanup_after_idle() noinstr")
Reported-by Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The condition in the trace_rcu_grace_period() in rcutree_dying_cpu() is
backwards, so that it uses the string "cpuofl" when the offline CPU is
blocking the current grace period and "cpuofl-bgp" otherwise. Given that
the "-bgp" stands for "blocking grace period", this is at best misleading.
This commit therefore switches these strings in order to correctly trace
whether the outgoing cpu blocks the current grace period.
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
