Commit Graph

1080 Commits

Author SHA1 Message Date
Peter Zijlstra
f7853c3424 locking/rtmutex: Fix task->pi_waiters integrity
Henry reported that rt_mutex_adjust_prio_check() has an ordering
problem and puts the lie to the comment in [7]. Sharing the sort key
between lock->waiters and owner->pi_waiters *does* create problems,
since unlike what the comment claims, holding [L] is insufficient.

Notably, consider:

	A
      /   \
     M1   M2
     |     |
     B     C

That is, task A owns both M1 and M2, B and C block on them. In this
case a concurrent chain walk (B & C) will modify their resp. sort keys
in [7] while holding M1->wait_lock and M2->wait_lock. So holding [L]
is meaningless, they're different Ls.

This then gives rise to a race condition between [7] and [11], where
the requeue of pi_waiters will observe an inconsistent tree order.

	B				C

  (holds M1->wait_lock,		(holds M2->wait_lock,
   holds B->pi_lock)		 holds A->pi_lock)

  [7]
  waiter_update_prio();
  ...
  [8]
  raw_spin_unlock(B->pi_lock);
  ...
  [10]
  raw_spin_lock(A->pi_lock);

				[11]
				rt_mutex_enqueue_pi();
				// observes inconsistent A->pi_waiters
				// tree order

Fixing this means either extending the range of the owner lock from
[10-13] to [6-13], with the immediate problem that this means [6-8]
hold both blocked and owner locks, or duplicating the sort key.

Since the locking in chain walk is horrible enough without having to
consider pi_lock nesting rules, duplicate the sort key instead.

By giving each tree their own sort key, the above race becomes
harmless, if C sees B at the old location, then B will correct things
(if they need correcting) when it walks up the chain and reaches A.

Fixes: fb00aca474 ("rtmutex: Turn the plist into an rb-tree")
Reported-by: Henry Wu <triangletrap12@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Henry Wu <triangletrap12@gmail.com>
Link: https://lkml.kernel.org/r/20230707161052.GF2883469%40hirez.programming.kicks-ass.net
2023-07-17 13:59:10 +02:00
Linus Torvalds
77b1a7f7a0 - Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in
top-level directories.
 
 - Douglas Anderson has added a new "buddy" mode to the hardlockup
   detector.  It permits the detector to work on architectures which
   cannot provide the required interrupts, by having CPUs periodically
   perform checks on other CPUs.
 
 - Zhen Lei has enhanced kexec's ability to support two crash regions.
 
 - Petr Mladek has done a lot of cleanup on the hard lockup detector's
   Kconfig entries.
 
 - And the usual bunch of singleton patches in various places.
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Merge tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-mm updates from Andrew Morton:

 - Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in top-level
   directories

 - Douglas Anderson has added a new "buddy" mode to the hardlockup
   detector. It permits the detector to work on architectures which
   cannot provide the required interrupts, by having CPUs periodically
   perform checks on other CPUs

 - Zhen Lei has enhanced kexec's ability to support two crash regions

 - Petr Mladek has done a lot of cleanup on the hard lockup detector's
   Kconfig entries

 - And the usual bunch of singleton patches in various places

* tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits)
  kernel/time/posix-stubs.c: remove duplicated include
  ocfs2: remove redundant assignment to variable bit_off
  watchdog/hardlockup: fix typo in config HARDLOCKUP_DETECTOR_PREFER_BUDDY
  powerpc: move arch_trigger_cpumask_backtrace from nmi.h to irq.h
  devres: show which resource was invalid in __devm_ioremap_resource()
  watchdog/hardlockup: define HARDLOCKUP_DETECTOR_ARCH
  watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64
  watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific
  watchdog/hardlockup: declare arch_touch_nmi_watchdog() only in linux/nmi.h
  watchdog/hardlockup: make the config checks more straightforward
  watchdog/hardlockup: sort hardlockup detector related config values a logical way
  watchdog/hardlockup: move SMP barriers from common code to buddy code
  watchdog/buddy: simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY
  watchdog/buddy: don't copy the cpumask in watchdog_next_cpu()
  watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called
  watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog()
  watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy()
  watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick()
  watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe()
  watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails
  ...
2023-06-28 10:59:38 -07:00
Linus Torvalds
bc6cb4d5bc Locking changes for v6.5:
- Introduce cmpxchg128() -- aka. the demise of cmpxchg_double().
 
   The cmpxchg128() family of functions is basically & functionally
   the same as cmpxchg_double(), but with a saner interface: instead
   of a 6-parameter horror that forced u128 - u64/u64-halves layout
   details on the interface and exposed users to complexity,
   fragility & bugs, use a natural 3-parameter interface with u128 types.
 
 - Restructure the generated atomic headers, and add
   kerneldoc comments for all of the generic atomic{,64,_long}_t
   operations. Generated definitions are much cleaner now,
   and come with documentation.
 
 - Implement lock_set_cmp_fn() on lockdep, for defining an ordering
   when taking multiple locks of the same type. This gets rid of
   one use of lockdep_set_novalidate_class() in the bcache code.
 
 - Fix raw_cpu_generic_try_cmpxchg() bug due to an unintended
   variable shadowing generating garbage code on Clang on certain
   ARM builds.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - Introduce cmpxchg128() -- aka. the demise of cmpxchg_double()

   The cmpxchg128() family of functions is basically & functionally the
   same as cmpxchg_double(), but with a saner interface.

   Instead of a 6-parameter horror that forced u128 - u64/u64-halves
   layout details on the interface and exposed users to complexity,
   fragility & bugs, use a natural 3-parameter interface with u128
   types.

 - Restructure the generated atomic headers, and add kerneldoc comments
   for all of the generic atomic{,64,_long}_t operations.

   The generated definitions are much cleaner now, and come with
   documentation.

 - Implement lock_set_cmp_fn() on lockdep, for defining an ordering when
   taking multiple locks of the same type.

   This gets rid of one use of lockdep_set_novalidate_class() in the
   bcache code.

 - Fix raw_cpu_generic_try_cmpxchg() bug due to an unintended variable
   shadowing generating garbage code on Clang on certain ARM builds.

* tag 'locking-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  locking/atomic: scripts: fix ${atomic}_dec_if_positive() kerneldoc
  percpu: Fix self-assignment of __old in raw_cpu_generic_try_cmpxchg()
  locking/atomic: treewide: delete arch_atomic_*() kerneldoc
  locking/atomic: docs: Add atomic operations to the driver basic API documentation
  locking/atomic: scripts: generate kerneldoc comments
  docs: scripts: kernel-doc: accept bitwise negation like ~@var
  locking/atomic: scripts: simplify raw_atomic*() definitions
  locking/atomic: scripts: simplify raw_atomic_long*() definitions
  locking/atomic: scripts: split pfx/name/sfx/order
  locking/atomic: scripts: restructure fallback ifdeffery
  locking/atomic: scripts: build raw_atomic_long*() directly
  locking/atomic: treewide: use raw_atomic*_<op>()
  locking/atomic: scripts: add trivial raw_atomic*_<op>()
  locking/atomic: scripts: factor out order template generation
  locking/atomic: scripts: remove leftover "${mult}"
  locking/atomic: scripts: remove bogus order parameter
  locking/atomic: xtensa: add preprocessor symbols
  locking/atomic: x86: add preprocessor symbols
  locking/atomic: sparc: add preprocessor symbols
  locking/atomic: sh: add preprocessor symbols
  ...
2023-06-27 14:14:30 -07:00
Linus Torvalds
af96134dc8 RCU pull request for v6.5
This pull contains the following branches:
 
 doc.2023.05.10a: Documentation updates
 
 fixes.2023.05.11a: Miscellaneous fixes, perhaps most notably:
 
 o	Remove RCU_NONIDLE().  The new visibility of most of the idle
 	loop to RCU has obsoleted this API.
 
 o	Make the RCU_SOFTIRQ callback-invocation time limit also apply
 	to the rcuc kthreads that invoke callbacks for CONFIG_PREEMPT_RT.
 
 o	Add a jiffies-based callback-invocation time limit to handle
 	long-running callbacks.  (The local_clock() function is only
 	invoked once per 32 callbacks due to its high overhead.)
 
 o	Stop rcu_tasks_invoke_cbs() from using never-onlined CPUs,
 	which fixes a bug that can occur on systems with non-contiguous
 	CPU numbering.
 
 kvfree.2023.05.10a: kvfree_rcu updates
 
 o	Eliminate the single-argument variant of k[v]free_rcu() now
 	that all uses have been converted to k[v]free_rcu_mightsleep().
 
 o	Add WARN_ON_ONCE() checks for k[v]free_rcu*() freeing callbacks
 	too soon.  Yes, this is closing the barn door after the horse
 	has escaped, but Murphy says that there will be more horses.
 
 nocb.2023.05.11a: Callback-offloading updates
 
 o	Fix a number of bugs involving the shrinker and lazy callbacks.
 
 rcu-tasks.2023.05.10a: Tasks RCU updates
 
 torture.2023.05.15a: Torture-test updates
 
 rcu-urgent.2023.06.06a: Urgent SRCU fix (already pulled)
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Merge tag 'rcu.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:
 "Documentation updates

  Miscellaneous fixes, perhaps most notably:

   - Remove RCU_NONIDLE(). The new visibility of most of the idle loop
     to RCU has obsoleted this API.

   - Make the RCU_SOFTIRQ callback-invocation time limit also apply to
     the rcuc kthreads that invoke callbacks for CONFIG_PREEMPT_RT.

   - Add a jiffies-based callback-invocation time limit to handle
     long-running callbacks. (The local_clock() function is only invoked
     once per 32 callbacks due to its high overhead.)

   - Stop rcu_tasks_invoke_cbs() from using never-onlined CPUs, which
     fixes a bug that can occur on systems with non-contiguous CPU
     numbering.

  kvfree_rcu updates:

   - Eliminate the single-argument variant of k[v]free_rcu() now that
     all uses have been converted to k[v]free_rcu_mightsleep().

   - Add WARN_ON_ONCE() checks for k[v]free_rcu*() freeing callbacks too
     soon. Yes, this is closing the barn door after the horse has
     escaped, but Murphy says that there will be more horses.

  Callback-offloading updates:

   - Fix a number of bugs involving the shrinker and lazy callbacks.

  Tasks RCU updates

  Torture-test updates"

* tag 'rcu.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (32 commits)
  torture: Remove duplicated argument -enable-kvm for ppc64
  doc/rcutorture: Add description of rcutorture.stall_cpu_block
  rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale
  rcu/rcuscale: Move rcu_scale_*() after kfree_scale_cleanup()
  rcutorture: Correct name of use_softirq module parameter
  locktorture: Add long_hold to adjust lock-hold delays
  rcu/nocb: Make shrinker iterate only over NOCB CPUs
  rcu-tasks: Stop rcu_tasks_invoke_cbs() from using never-onlined CPUs
  rcu: Make rcu_cpu_starting() rely on interrupts being disabled
  rcu: Mark rcu_cpu_kthread() accesses to ->rcu_cpu_has_work
  rcu: Mark additional concurrent load from ->cpu_no_qs.b.exp
  rcu: Employ jiffies-based backstop to callback time limit
  rcu: Check callback-invocation time limit for rcuc kthreads
  rcu: Remove RCU_NONIDLE()
  rcu: Add more RCU files to kernel-api.rst
  rcu-tasks: Clarify the cblist_init_generic() function's pr_info() output
  rcu-tasks: Avoid pr_info() with spin lock in cblist_init_generic()
  rcu/nocb: Recheck lazy callbacks under the ->nocb_lock from shrinker
  rcu/nocb: Fix shrinker race against callback enqueuer
  rcu/nocb: Protect lazy shrinker against concurrent (de-)offloading
  ...
2023-06-27 10:37:01 -07:00
Arnd Bergmann
ff7138813a locking: add lockevent_read() prototype
lockevent_read() has a __weak definition and the only caller in
kernel/locking/lock_events.c, plus a strong definition in qspinlock_stat.h
that overrides it, but no other declaration.  This causes a W=1 warning:

kernel/locking/lock_events.c:61:16: error: no previous prototype for 'lockevent_read' [-Werror=missing-prototypes]

Add shared prototype to avoid the warnings.

Link: https://lkml.kernel.org/r/20230517131102.934196-7-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-09 17:44:15 -07:00
Linus Torvalds
d8f14b84fe Two fixes for debugobjects:
- Prevent that the allocation path wakes up kswapd. That's a long
     standing issue due to the GFP_ATOMIC allocation flag. As debug objects
     can be invoked from pretty much any context waking kswapd can end up
     in arbitrary lock chains versus the waitqueue lock.
 
   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool().
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Merge tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull debugobjects fixes from Thomas Gleixner:
 "Two fixes for debugobjects:

   - Prevent the allocation path from waking up kswapd.

     That's a long standing issue due to the GFP_ATOMIC allocation flag.
     As debug objects can be invoked from pretty much any context waking
     kswapd can end up in arbitrary lock chains versus the waitqueue
     lock

   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool()"

* tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobjects: Don't wake up kswapd from fill_pool()
  debugobjects,locking: Annotate debug_object_fill_pool() wait type violation
2023-05-28 07:15:33 -04:00
Kent Overstreet
eb1cfd09f7 lockdep: Add lock_set_cmp_fn() annotation
This implements a new interface to lockdep, lock_set_cmp_fn(), for
defining a custom ordering when taking multiple locks of the same
class.

This is an alternative to subclasses, but can not fully replace them
since subclasses allow lock hierarchies with other clasees
inter-twined, while this relies on pure class nesting.

Specifically, if A is our nesting class then:

  A/0 <- B <- A/1

Would be a valid lock order with subclasses (each subclass really is a
full class from the validation PoV) but not with this annotation,
which requires all nesting to be consecutive.

Example output:

| ============================================
| WARNING: possible recursive locking detected
| 6.2.0-rc8-00003-g7d81e591ca6a-dirty #15 Not tainted
| --------------------------------------------
| kworker/14:3/938 is trying to acquire lock:
| ffff8880143218c8 (&b->lock l=0 0:2803368){++++}-{3:3}, at: bch_btree_node_get.part.0+0x81/0x2b0
|
| but task is already holding lock:
| ffff8880143de8c8 (&b->lock l=1 1048575:9223372036854775807){++++}-{3:3}, at: __bch_btree_map_nodes+0xea/0x1e0
| and the lock comparison function returns 1:
|
| other info that might help us debug this:
|  Possible unsafe locking scenario:
|
|        CPU0
|        ----
|   lock(&b->lock l=1 1048575:9223372036854775807);
|   lock(&b->lock l=0 0:2803368);
|
|  *** DEADLOCK ***
|
|  May be due to missing lock nesting notation
|
| 3 locks held by kworker/14:3/938:
|  #0: ffff888005ea9d38 ((wq_completion)bcache){+.+.}-{0:0}, at: process_one_work+0x1ec/0x530
|  #1: ffff8880098c3e70 ((work_completion)(&cl->work)#3){+.+.}-{0:0}, at: process_one_work+0x1ec/0x530
|  #2: ffff8880143de8c8 (&b->lock l=1 1048575:9223372036854775807){++++}-{3:3}, at: __bch_btree_map_nodes+0xea/0x1e0

[peterz: extended changelog]
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230509195847.1745548-1-kent.overstreet@linux.dev
2023-05-19 12:35:10 +02:00
Paul E. McKenney
f8619c300f locktorture: Add long_hold to adjust lock-hold delays
This commit adds a long_hold module parameter to allow testing diagnostics
for excessive lock-hold times.  Also adjust torture_param() invocations
for longer line length while in the area.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
2023-05-11 13:46:36 -07:00
John Stultz
92cc5d00a4 locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers
Apparently despite it being marked inline, the compiler
may not inline __down_read_common() which makes it difficult
to identify the cause of lock contention, as the blocked
function in traceevents will always be listed as
__down_read_common().

So this patch adds __always_inline annotation to the common
function (as well as the inlined helper callers) to force it to
be inlined so the blocking function will be listed (via Wchan)
in traceevents.

Fixes: c995e638cc ("locking/rwsem: Fold __down_{read,write}*()")
Reported-by: Tim Murray <timmurray@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20230503023351.2832796-1-jstultz@google.com
2023-05-08 10:58:24 +02:00
Linus Torvalds
b115d85a95 Locking changes in v6.4:
- Introduce local{,64}_try_cmpxchg() - a slightly more optimal
    primitive, which will be used in perf events ring-buffer code.
 
  - Simplify/modify rwsems on PREEMPT_RT, to address writer starvation.
 
  - Misc cleanups/fixes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-05-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - Introduce local{,64}_try_cmpxchg() - a slightly more optimal
   primitive, which will be used in perf events ring-buffer code

 - Simplify/modify rwsems on PREEMPT_RT, to address writer starvation

 - Misc cleanups/fixes

* tag 'locking-core-2023-05-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/atomic: Correct (cmp)xchg() instrumentation
  locking/x86: Define arch_try_cmpxchg_local()
  locking/arch: Wire up local_try_cmpxchg()
  locking/generic: Wire up local{,64}_try_cmpxchg()
  locking/atomic: Add generic try_cmpxchg{,64}_local() support
  locking/rwbase: Mitigate indefinite writer starvation
  locking/arch: Rename all internal __xchg() names to __arch_xchg()
2023-05-05 12:56:55 -07:00
Peter Zijlstra
0cce06ba85 debugobjects,locking: Annotate debug_object_fill_pool() wait type violation
There is an explicit wait-type violation in debug_object_fill_pool()
for PREEMPT_RT=n kernels which allows them to more easily fill the
object pool and reduce the chance of allocation failures.

Lockdep's wait-type checks are designed to check the PREEMPT_RT
locking rules even for PREEMPT_RT=n kernels and object to this, so
create a lockdep annotation to allow this to stand.

Specifically, create a 'lock' type that overrides the inner wait-type
while it is held -- allowing one to temporarily raise it, such that
the violation is hidden.

Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Qi Zheng <zhengqi.arch@bytedance.com>
Link: https://lkml.kernel.org/r/20230429100614.GA1489784@hirez.programming.kicks-ass.net
2023-05-02 14:48:14 +02:00
Sebastian Andrzej Siewior
286deb7ec0 locking/rwbase: Mitigate indefinite writer starvation
On PREEMPT_RT, rw_semaphore and rwlock_t locks are unfair to writers.
Readers can indefinitely acquire the lock unless the writer fully acquired
the lock, which might never happen if there is always a reader in the
critical section owning the lock.

Mel Gorman reported that since LTP-20220121 the dio_truncate test case
went from having 1 reader to having 16 readers and that number of readers
is sufficient to prevent the down_write ever succeeding while readers
exist. Eventually the test is killed after 30 minutes as a failure.

Mel proposed a timeout to limit how long a writer can be blocked until
the reader is forced into the slowpath.

Thomas argued that there is no added value by providing this timeout.  From
a PREEMPT_RT point of view, there are no critical rw_semaphore or rwlock_t
locks left where the reader must be preferred.

Mitigate indefinite writer starvation by forcing the READER into the
slowpath once the WRITER attempts to acquire the lock.

Reported-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/877cwbq4cq.ffs@tglx
Link: https://lore.kernel.org/r/20230321161140.HMcQEhHb@linutronix.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-29 09:08:52 +02:00
Linus Torvalds
5dfb75e842 RCU Changes for 6.4:
o  MAINTAINERS files additions and changes.
  o  Fix hotplug warning in nohz code.
  o  Tick dependency changes by Zqiang.
  o  Lazy-RCU shrinker fixes by Zqiang.
  o  rcu-tasks stall reporting improvements by Neeraj.
  o  Initial changes for renaming of k[v]free_rcu() to its new k[v]free_rcu_mightsleep()
     name for robustness.
  o  Documentation Updates:
  o  Significant changes to srcu_struct size.
  o  Deadlock detection for srcu_read_lock() vs synchronize_srcu() from Boqun.
  o  rcutorture and rcu-related tool, which are targeted for v6.4 from Boqun's tree.
  o  Other misc changes.
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Merge tag 'rcu.6.4.april5.2023.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux

Pull RCU updates from Joel Fernandes:

 - Updates and additions to MAINTAINERS files, with Boqun being added to
   the RCU entry and Zqiang being added as an RCU reviewer.

   I have also transitioned from reviewer to maintainer; however, Paul
   will be taking over sending RCU pull-requests for the next merge
   window.

 - Resolution of hotplug warning in nohz code, achieved by fixing
   cpu_is_hotpluggable() through interaction with the nohz subsystem.

   Tick dependency modifications by Zqiang, focusing on fixing usage of
   the TICK_DEP_BIT_RCU_EXP bitmask.

 - Avoid needless calls to the rcu-lazy shrinker for CONFIG_RCU_LAZY=n
   kernels, fixed by Zqiang.

 - Improvements to rcu-tasks stall reporting by Neeraj.

 - Initial renaming of k[v]free_rcu() to k[v]free_rcu_mightsleep() for
   increased robustness, affecting several components like mac802154,
   drbd, vmw_vmci, tracing, and more.

   A report by Eric Dumazet showed that the API could be unknowingly
   used in an atomic context, so we'd rather make sure they know what
   they're asking for by being explicit:

      https://lore.kernel.org/all/20221202052847.2623997-1-edumazet@google.com/

 - Documentation updates, including corrections to spelling,
   clarifications in comments, and improvements to the srcu_size_state
   comments.

 - Better srcu_struct cache locality for readers, by adjusting the size
   of srcu_struct in support of SRCU usage by Christoph Hellwig.

 - Teach lockdep to detect deadlocks between srcu_read_lock() vs
   synchronize_srcu() contributed by Boqun.

   Previously lockdep could not detect such deadlocks, now it can.

 - Integration of rcutorture and rcu-related tools, targeted for v6.4
   from Boqun's tree, featuring new SRCU deadlock scenarios, test_nmis
   module parameter, and more

 - Miscellaneous changes, various code cleanups and comment improvements

* tag 'rcu.6.4.april5.2023.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux: (71 commits)
  checkpatch: Error out if deprecated RCU API used
  mac802154: Rename kfree_rcu() to kvfree_rcu_mightsleep()
  rcuscale: Rename kfree_rcu() to kfree_rcu_mightsleep()
  ext4/super: Rename kfree_rcu() to kfree_rcu_mightsleep()
  net/mlx5: Rename kfree_rcu() to kfree_rcu_mightsleep()
  net/sysctl: Rename kvfree_rcu() to kvfree_rcu_mightsleep()
  lib/test_vmalloc.c: Rename kvfree_rcu() to kvfree_rcu_mightsleep()
  tracing: Rename kvfree_rcu() to kvfree_rcu_mightsleep()
  misc: vmw_vmci: Rename kvfree_rcu() to kvfree_rcu_mightsleep()
  drbd: Rename kvfree_rcu() to kvfree_rcu_mightsleep()
  rcu: Protect rcu_print_task_exp_stall() ->exp_tasks access
  rcu: Avoid stack overflow due to __rcu_irq_enter_check_tick() being kprobe-ed
  rcu-tasks: Report stalls during synchronize_srcu() in rcu_tasks_postscan()
  rcu: Permit start_poll_synchronize_rcu_expedited() to be invoked early
  rcu: Remove never-set needwake assignment from rcu_report_qs_rdp()
  rcu: Register rcu-lazy shrinker only for CONFIG_RCU_LAZY=y kernels
  rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check
  rcu: Fix set/clear TICK_DEP_BIT_RCU_EXP bitmask race
  rcu/trace: use strscpy() to instead of strncpy()
  tick/nohz: Fix cpu_is_hotpluggable() by checking with nohz subsystem
  ...
2023-04-24 12:16:14 -07:00
Boqun Feng
0471db447c locking/lockdep: Improve the deadlock scenario print for sync and read lock
Lock scenario print is always a weak spot of lockdep splats. Improvement
can be made if we rework the dependency search and the error printing.

However without touching the graph search, we can improve a little for
the circular deadlock case, since we have the to-be-added lock
dependency, and know whether these two locks are read/write/sync.

In order to know whether a held_lock is sync or not, a bit was
"stolen" from ->references, which reduce our limit for the same lock
class nesting from 2^12 to 2^11, and it should still be good enough.

Besides, since we now have bit in held_lock for sync, we don't need the
"hardirqoffs being 1" trick, and also we can avoid the __lock_release()
if we jump out of __lock_acquire() before the held_lock stored.

With these changes, a deadlock case evolved with read lock and sync gets
a better print-out from:

	[...]  Possible unsafe locking scenario:
	[...]
	[...]        CPU0                    CPU1
	[...]        ----                    ----
	[...]   lock(srcuA);
	[...]                                lock(srcuB);
	[...]                                lock(srcuA);
	[...]   lock(srcuB);

to

	[...]  Possible unsafe locking scenario:
	[...]
	[...]        CPU0                    CPU1
	[...]        ----                    ----
	[...]   rlock(srcuA);
	[...]                                lock(srcuB);
	[...]                                lock(srcuA);
	[...]   sync(srcuB);

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-27 11:16:04 -07:00
Boqun Feng
60a1a64ec0 locking: Reduce the number of locks in ww_mutex stress tests
The stress test in test_ww_mutex_init() uses 4095 locks since
lockdep::reference has 12 bits, and since we are going to reduce it to
11 bits to support lock_sync(), and 2047 is still a reasonable number of
the max nesting level for locks, so adjust the test.

Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/oe-lkp/202302011445.9d99dae2-oliver.sang@intel.com
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-27 11:16:01 -07:00
Boqun Feng
2f1f043e7b locking/lockdep: Introduce lock_sync()
Currently, functions like synchronize_srcu() do not have lockdep
annotations resembling those of other write-side locking primitives.
Such annotations might look as follows:

	lock_acquire();
	lock_release();

Such annotations would tell lockdep that synchronize_srcu() acts like
an empty critical section that waits for other (read-side) critical
sections to finish.  This would definitely catch some deadlock, but
as pointed out by Paul Mckenney [1], this could also introduce false
positives because of irq-safe/unsafe detection.  Of course, there are
tricks could help with this:

	might_sleep(); // Existing statement in __synchronize_srcu().
	if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
		local_irq_disable();
		lock_acquire();
		lock_release();
		local_irq_enable();
	}

But it would be better for lockdep to provide a separate annonation for
functions like synchronize_srcu(), so that people won't need to repeat
the ugly tricks above.

Therefore introduce lock_sync(), which is simply an lock+unlock
pair with no irq safe/unsafe deadlock check.  This works because the
to-be-annontated functions do not create real critical sections, and
there is therefore no way that irq can create extra dependencies.

[1]: https://lore.kernel.org/lkml/20180412021233.ewncg5jjuzjw3x62@tardis/

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
[ boqun: Fix typos reported by Davidlohr Bueso and Paul E. Mckenney ]
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-03-27 11:15:23 -07:00
Zqiang
5d65cf6ae6 locktorture: Add raw_spinlock* torture tests for PREEMPT_RT kernels
In PREEMPT_RT kernels, both spin_lock() and spin_lock_irq() are converted
to sleepable rt_spin_lock().  This means that the interrupt related
suffixes for spin_lock/unlock(_irq, irqsave/irqrestore) do not affect
the CPU's interrupt state. This commit therefore adds raw spin-lock
torture tests.  This in turn permits pure spin locks to be tested in
PREEMPT_RT kernels.

Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Suggested-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-07 10:13:57 -08:00
John Stultz
45bcf0bd8c locktorture: With nested locks, occasionally skip main lock
If we're using nested locking to stress things, occasionally
skip taking the main lock, so that we can get some different
contention patterns between the writers (to hopefully get two
disjoint blocked trees)

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Co-developed-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-07 10:13:57 -08:00
John Stultz
ae4823e427 locktorture: Add nested locking to rtmutex torture tests
This patch adds randomized nested locking to the rtmutex torture
tests. Additionally it adds LOCK09 config files for testing
rtmutexes with nested locking.

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Co-developed-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-07 10:13:57 -08:00
John Stultz
3e5aeaf534 locktorture: Add nested locking to mutex torture tests
This patch adds randomized nested locking to the mutex torture
tests, as well as new LOCK08 config files for testing mutexes
with nested locking

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Co-developed-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-07 10:13:57 -08:00
John Stultz
b63343207d locktorture: Add nested_[un]lock() hooks and nlocks parameter
In order to extend locktorture to support lock nesting, add
nested_lock() and nested_unlock() hooks to the torture ops.

These take a 32bit lockset mask which is generated at random,
so some number of locks will be taken before the main lock is
taken and released afterwards.

Additionally, add nested_locks module parameter to allow
specifying the number of nested locks to be used.

This has been helpful to uncover issues in the proxy-exec
series development.

This was inspired by locktorture extensions originally implemented
by Connor O'Brien, for stress testing the proxy-execution series:
  https://lore.kernel.org/lkml/20221003214501.2050087-12-connoro@google.com/

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Co-developed-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-07 10:13:57 -08:00
Linus Torvalds
8cc01d43f8 RCU pull request for v6.3
This pull request contains the following branches:
 
 doc.2023.01.05a: Documentation updates.
 
 fixes.2023.01.23a: Miscellaneous fixes, perhaps most notably:
 
 o	Throttling callback invocation based on the number of callbacks
 	that are now ready to invoke instead of on the total number
 	of callbacks.
 
 o	Several patches that suppress false-positive boot-time
 	diagnostics, for example, due to lockdep not yet being
 	initialized.
 
 o	Make expedited RCU CPU stall warnings dump stacks of any tasks
 	that are blocking the stalled grace period.  (Normal RCU CPU
 	stall warnings have doen this for mnay years.)
 
 o	Lazy-callback fixes to avoid delays during boot, suspend, and
 	resume.  (Note that lazy callbacks must be explicitly enabled,
 	so this should not (yet) affect production use cases.)
 
 kvfree.2023.01.03a: Cause kfree_rcu() and friends to take advantage of
 	polled grace periods, thus reducing memory footprint by almost
 	two orders of magnitude, admittedly on a microbenchmark.
 	This series also begins the transition from kfree_rcu(p) to
 	kfree_rcu_mightsleep(p).  This transition was motivated by bugs
 	where kfree_rcu(p), which can block, was typed instead of the
 	intended kfree_rcu(p, rh).
 
 srcu.2023.01.03a: SRCU updates, perhaps most notably fixing a bug that
 	causes SRCU to fail when booted on a system with a non-zero boot
 	CPU.  This surprising situation actually happens for kdump kernels
 	on the powerpc architecture.  It also adds an srcu_down_read()
 	and srcu_up_read(), which act like srcu_read_lock() and
 	srcu_read_unlock(), but allow an SRCU read-side critical section
 	to be handed off from one task to another.
 
 srcu-always.2023.02.02a: Cleans up the now-useless SRCU Kconfig option.
 	There are a few more commits that are not yet acked or pulled
 	into maintainer trees, and these will be in a pull request for
 	a later merge window.
 
 tasks.2023.01.03a: RCU-tasks updates, perhaps most notably these fixes:
 
 o	A strange interaction between PID-namespace unshare and the
 	RCU-tasks grace period that results in a low-probability but
 	very real hang.
 
 o	A race between an RCU tasks rude grace period on a single-CPU
 	system and CPU-hotplug addition of the second CPU that can result
 	in a too-short grace period.
 
 o	A race between shrinking RCU tasks down to a single callback list
 	and queuing a new callback to some other CPU, but where that
 	queuing is delayed for more than an RCU grace period.  This can
 	result in that callback being stranded on the non-boot CPU.
 
 torture.2023.01.05a: Torture-test updates and fixes.
 
 torturescript.2023.01.03a: Torture-test scripting updates and fixes.
 
 stall.2023.01.09a: Provide additional RCU CPU stall-warning information
 	in kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y, and
 	restore the full five-minute timeout limit for expedited RCU
 	CPU stall warnings.
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Merge tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes, perhaps most notably:

      - Throttling callback invocation based on the number of callbacks
        that are now ready to invoke instead of on the total number of
        callbacks

      - Several patches that suppress false-positive boot-time
        diagnostics, for example, due to lockdep not yet being
        initialized

      - Make expedited RCU CPU stall warnings dump stacks of any tasks
        that are blocking the stalled grace period. (Normal RCU CPU
        stall warnings have done this for many years)

      - Lazy-callback fixes to avoid delays during boot, suspend, and
        resume. (Note that lazy callbacks must be explicitly enabled, so
        this should not (yet) affect production use cases)

 - Make kfree_rcu() and friends take advantage of polled grace periods,
   thus reducing memory footprint by almost two orders of magnitude,
   admittedly on a microbenchmark

   This also begins the transition from kfree_rcu(p) to
   kfree_rcu_mightsleep(p). This transition was motivated by bugs where
   kfree_rcu(p), which can block, was typed instead of the intended
   kfree_rcu(p, rh)

 - SRCU updates, perhaps most notably fixing a bug that causes SRCU to
   fail when booted on a system with a non-zero boot CPU. This
   surprising situation actually happens for kdump kernels on the
   powerpc architecture

   This also adds an srcu_down_read() and srcu_up_read(), which act like
   srcu_read_lock() and srcu_read_unlock(), but allow an SRCU read-side
   critical section to be handed off from one task to another

 - Clean up the now-useless SRCU Kconfig option

   There are a few more commits that are not yet acked or pulled into
   maintainer trees, and these will be in a pull request for a later
   merge window

 - RCU-tasks updates, perhaps most notably these fixes:

      - A strange interaction between PID-namespace unshare and the
        RCU-tasks grace period that results in a low-probability but
        very real hang

      - A race between an RCU tasks rude grace period on a single-CPU
        system and CPU-hotplug addition of the second CPU that can
        result in a too-short grace period

      - A race between shrinking RCU tasks down to a single callback
        list and queuing a new callback to some other CPU, but where
        that queuing is delayed for more than an RCU grace period. This
        can result in that callback being stranded on the non-boot CPU

 - Torture-test updates and fixes

 - Torture-test scripting updates and fixes

 - Provide additional RCU CPU stall-warning information in kernels built
   with CONFIG_RCU_CPU_STALL_CPUTIME=y, and restore the full five-minute
   timeout limit for expedited RCU CPU stall warnings

* tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (80 commits)
  rcu/kvfree: Add kvfree_rcu_mightsleep() and kfree_rcu_mightsleep()
  kernel/notifier: Remove CONFIG_SRCU
  init: Remove "select SRCU"
  fs/quota: Remove "select SRCU"
  fs/notify: Remove "select SRCU"
  fs/btrfs: Remove "select SRCU"
  fs: Remove CONFIG_SRCU
  drivers/pci/controller: Remove "select SRCU"
  drivers/net: Remove "select SRCU"
  drivers/md: Remove "select SRCU"
  drivers/hwtracing/stm: Remove "select SRCU"
  drivers/dax: Remove "select SRCU"
  drivers/base: Remove CONFIG_SRCU
  rcu: Disable laziness if lazy-tracking says so
  rcu: Track laziness during boot and suspend
  rcu: Remove redundant call to rcu_boost_kthread_setaffinity()
  rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts
  rcu: Align the output of RCU CPU stall warning messages
  rcu: Add RCU stall diagnosis information
  sched: Add helper nr_context_switches_cpu()
  ...
2023-02-21 10:45:51 -08:00
Linus Torvalds
1f2d9ffc7a Scheduler updates in this cycle are:
- Improve the scalability of the CFS bandwidth unthrottling logic
    with large number of CPUs.
 
  - Fix & rework various cpuidle routines, simplify interaction with
    the generic scheduler code. Add __cpuidle methods as noinstr to
    objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks.
 
  - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS,
    to query previously issued registrations.
 
  - Limit scheduler slice duration to the sysctl_sched_latency period,
    to improve scheduling granularity with a large number of SCHED_IDLE
    tasks.
 
  - Debuggability enhancement on sys_exit(): warn about disabled IRQs,
    but also enable them to prevent a cascade of followup problems and
    repeat warnings.
 
  - Fix the rescheduling logic in prio_changed_dl().
 
  - Micro-optimize cpufreq and sched-util methods.
 
  - Micro-optimize ttwu_runnable()
 
  - Micro-optimize the idle-scanning in update_numa_stats(),
    select_idle_capacity() and steal_cookie_task().
 
  - Update the RSEQ code & self-tests
 
  - Constify various scheduler methods
 
  - Remove unused methods
 
  - Refine __init tags
 
  - Documentation updates
 
  - ... Misc other cleanups, fixes
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Improve the scalability of the CFS bandwidth unthrottling logic with
   large number of CPUs.

 - Fix & rework various cpuidle routines, simplify interaction with the
   generic scheduler code. Add __cpuidle methods as noinstr to objtool's
   noinstr detection and fix boatloads of cpuidle bugs & quirks.

 - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query
   previously issued registrations.

 - Limit scheduler slice duration to the sysctl_sched_latency period, to
   improve scheduling granularity with a large number of SCHED_IDLE
   tasks.

 - Debuggability enhancement on sys_exit(): warn about disabled IRQs,
   but also enable them to prevent a cascade of followup problems and
   repeat warnings.

 - Fix the rescheduling logic in prio_changed_dl().

 - Micro-optimize cpufreq and sched-util methods.

 - Micro-optimize ttwu_runnable()

 - Micro-optimize the idle-scanning in update_numa_stats(),
   select_idle_capacity() and steal_cookie_task().

 - Update the RSEQ code & self-tests

 - Constify various scheduler methods

 - Remove unused methods

 - Refine __init tags

 - Documentation updates

 - Misc other cleanups, fixes

* tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits)
  sched/rt: pick_next_rt_entity(): check list_entry
  sched/deadline: Add more reschedule cases to prio_changed_dl()
  sched/fair: sanitize vruntime of entity being placed
  sched/fair: Remove capacity inversion detection
  sched/fair: unlink misfit task from cpu overutilized
  objtool: mem*() are not uaccess safe
  cpuidle: Fix poll_idle() noinstr annotation
  sched/clock: Make local_clock() noinstr
  sched/clock/x86: Mark sched_clock() noinstr
  x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read()
  x86/atomics: Always inline arch_atomic64*()
  cpuidle: tracing, preempt: Squash _rcuidle tracing
  cpuidle: tracing: Warn about !rcu_is_watching()
  cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG
  cpuidle: drivers: firmware: psci: Dont instrument suspend code
  KVM: selftests: Fix build of rseq test
  exit: Detect and fix irq disabled state in oops
  cpuidle, arm64: Fix the ARM64 cpuidle logic
  cpuidle: mvebu: Fix duplicate flags assignment
  sched/fair: Limit sched slice duration
  ...
2023-02-20 17:41:08 -08:00
Linus Torvalds
6e649d0856 Updates for this cycle were:
- rwsem micro-optimizations
  - spinlock micro-optimizations
  - cleanups, simplifications
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - rwsem micro-optimizations

 - spinlock micro-optimizations

 - cleanups, simplifications

* tag 'locking-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  vduse: Remove include of rwlock.h
  locking/lockdep: Remove lockdep_init_map_crosslock.
  x86/ACPI/boot: Use try_cmpxchg() in __acpi_{acquire,release}_global_lock()
  x86/PAT: Use try_cmpxchg() in set_page_memtype()
  locking/rwsem: Disable preemption in all down_write*() and up_write() code paths
  locking/rwsem: Disable preemption in all down_read*() and up_read() code paths
  locking/rwsem: Prevent non-first waiter from spinning in down_write() slowpath
  locking/qspinlock: Micro-optimize pending state waiting for unlock
2023-02-20 17:18:23 -08:00
Wander Lairson Costa
db370a8b9f rtmutex: Ensure that the top waiter is always woken up
Let L1 and L2 be two spinlocks.

Let T1 be a task holding L1 and blocked on L2. T1, currently, is the top
waiter of L2.

Let T2 be the task holding L2.

Let T3 be a task trying to acquire L1.

The following events will lead to a state in which the wait queue of L2
isn't empty, but no task actually holds the lock.

T1                T2                                  T3
==                ==                                  ==

                                                      spin_lock(L1)
                                                      | raw_spin_lock(L1->wait_lock)
                                                      | rtlock_slowlock_locked(L1)
                                                      | | task_blocks_on_rt_mutex(L1, T3)
                                                      | | | orig_waiter->lock = L1
                                                      | | | orig_waiter->task = T3
                                                      | | | raw_spin_unlock(L1->wait_lock)
                                                      | | | rt_mutex_adjust_prio_chain(T1, L1, L2, orig_waiter, T3)
                  spin_unlock(L2)                     | | | |
                  | rt_mutex_slowunlock(L2)           | | | |
                  | | raw_spin_lock(L2->wait_lock)    | | | |
                  | | wakeup(T1)                      | | | |
                  | | raw_spin_unlock(L2->wait_lock)  | | | |
                                                      | | | | waiter = T1->pi_blocked_on
                                                      | | | | waiter == rt_mutex_top_waiter(L2)
                                                      | | | | waiter->task == T1
                                                      | | | | raw_spin_lock(L2->wait_lock)
                                                      | | | | dequeue(L2, waiter)
                                                      | | | | update_prio(waiter, T1)
                                                      | | | | enqueue(L2, waiter)
                                                      | | | | waiter != rt_mutex_top_waiter(L2)
                                                      | | | | L2->owner == NULL
                                                      | | | | wakeup(T1)
                                                      | | | | raw_spin_unlock(L2->wait_lock)
T1 wakes up
T1 != top_waiter(L2)
schedule_rtlock()

If the deadline of T1 is updated before the call to update_prio(), and the
new deadline is greater than the deadline of the second top waiter, then
after the requeue, T1 is no longer the top waiter, and the wrong task is
woken up which will then go back to sleep because it is not the top waiter.

This can be reproduced in PREEMPT_RT with stress-ng:

while true; do
    stress-ng --sched deadline --sched-period 1000000000 \
    	    --sched-runtime 800000000 --sched-deadline \
    	    1000000000 --mmapfork 23 -t 20
done

A similar issue was pointed out by Thomas versus the cases where the top
waiter drops out early due to a signal or timeout, which is a general issue
for all regular rtmutex use cases, e.g. futex.

The problematic code is in rt_mutex_adjust_prio_chain():

    	// Save the top waiter before dequeue/enqueue
	prerequeue_top_waiter = rt_mutex_top_waiter(lock);

	rt_mutex_dequeue(lock, waiter);
	waiter_update_prio(waiter, task);
	rt_mutex_enqueue(lock, waiter);

	// Lock has no owner?
	if (!rt_mutex_owner(lock)) {
	   	// Top waiter changed		      			   
  ---->		if (prerequeue_top_waiter != rt_mutex_top_waiter(lock))
  ---->			wake_up_state(waiter->task, waiter->wake_state);

This only takes the case into account where @waiter is the new top waiter
due to the requeue operation.

But it fails to handle the case where @waiter is not longer the top
waiter due to the requeue operation.

Ensure that the new top waiter is woken up so in all cases so it can take
over the ownerless lock.

[ tglx: Amend changelog, add Fixes tag ]

Fixes: c014ef69b3 ("locking/rtmutex: Add wake_state to rt_mutex_waiter")
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230117172649.52465-1-wander@redhat.com
Link: https://lore.kernel.org/r/20230202123020.14844-1-wander@redhat.com
2023-02-06 14:49:13 +01:00
Peter Zijlstra
5a5d7e9bad cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG
In order to avoid WARN/BUG from generating nested or even recursive
warnings, force rcu_is_watching() true during
WARN/lockdep_rcu_suspicious().

Notably things like unwinding the stack can trigger rcu_dereference()
warnings, which then triggers more unwinding which then triggers more
warnings etc..

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.408156109@infradead.org
2023-01-31 15:01:45 +01:00
Waiman Long
1d61659ced locking/rwsem: Disable preemption in all down_write*() and up_write() code paths
The previous patch has disabled preemption in all the down_read() and
up_read() code paths. For symmetry, this patch extends commit:

  48dfb5d256 ("locking/rwsem: Disable preemption while trying for rwsem lock")

... to have preemption disabled in all the down_write() and up_write()
code paths, including downgrade_write().

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126003628.365092-4-longman@redhat.com
2023-01-26 11:46:46 +01:00
Waiman Long
3f5245538a locking/rwsem: Disable preemption in all down_read*() and up_read() code paths
Commit:

  91d2a812df ("locking/rwsem: Make handoff writer optimistically spin on owner")

... assumes that when the owner field is changed to NULL, the lock will
become free soon. But commit:

  48dfb5d256 ("locking/rwsem: Disable preemption while trying for rwsem lock")

... disabled preemption when acquiring rwsem for write.

However, preemption has not yet been disabled when acquiring a read lock
on a rwsem.  So a reader can add a RWSEM_READER_BIAS to count without
setting owner to signal a reader, got preempted out by a RT task which
then spins in the writer slowpath as owner remains NULL leading to live lock.

One easy way to fix this problem is to disable preemption at all the
down_read*() and up_read() code paths as implemented in this patch.

Fixes: 91d2a812df ("locking/rwsem: Make handoff writer optimistically spin on owner")
Reported-by: Mukesh Ojha <quic_mojha@quicinc.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126003628.365092-3-longman@redhat.com
2023-01-26 11:46:46 +01:00
Waiman Long
b613c7f314 locking/rwsem: Prevent non-first waiter from spinning in down_write() slowpath
A non-first waiter can potentially spin in the for loop of
rwsem_down_write_slowpath() without sleeping but fail to acquire the
lock even if the rwsem is free if the following sequence happens:

  Non-first RT waiter    First waiter      Lock holder
  -------------------    ------------      -----------
  Acquire wait_lock
  rwsem_try_write_lock():
    Set handoff bit if RT or
      wait too long
    Set waiter->handoff_set
  Release wait_lock
                         Acquire wait_lock
                         Inherit waiter->handoff_set
                         Release wait_lock
					   Clear owner
                                           Release lock
  if (waiter.handoff_set) {
    rwsem_spin_on_owner(();
    if (OWNER_NULL)
      goto trylock_again;
  }
  trylock_again:
  Acquire wait_lock
  rwsem_try_write_lock():
     if (first->handoff_set && (waiter != first))
	return false;
  Release wait_lock

A non-first waiter cannot really acquire the rwsem even if it mistakenly
believes that it can spin on OWNER_NULL value. If that waiter happens
to be an RT task running on the same CPU as the first waiter, it can
block the first waiter from acquiring the rwsem leading to live lock.
Fix this problem by making sure that a non-first waiter cannot spin in
the slowpath loop without sleeping.

Fixes: d257cc8cb8 ("locking/rwsem: Make handoff bit handling more consistent")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230126003628.365092-2-longman@redhat.com
2023-01-26 11:46:45 +01:00
Joel Fernandes (Google)
c24501b240 locktorture: Make the rt_boost factor a tunable
The rt boosting in locktorture has a factor variable s currently large enough
that boosting only happens once every minute or so. Add a tunable to reduce the
factor so that boosting happens more often, to test paths and arrive at failure
modes earlier. With this change, I can set the factor to like 50 and have the
boosting happens every 10 seconds or so.

Tested with boot parameters:
locktorture.torture_type=mutex_lock
locktorture.onoff_interval=1
locktorture.nwriters_stress=8
locktorture.stutter=0
locktorture.rt_boost=1
locktorture.rt_boost_factor=50
locktorture.nlocks=3

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-01-05 12:10:35 -08:00
Joel Fernandes (Google)
e01f3a1a58 locktorture: Allow non-rtmutex lock types to be boosted
Currently RT boosting is only done for rtmutex_lock, however with proxy
execution, we also have the mutex_lock participating in priorities. To
exercise the testing better, add RT boosting to other lock testing types
as well, using a new knob (rt_boost).

Tested with boot parameters:
locktorture.torture_type=mutex_lock
locktorture.onoff_interval=1
locktorture.nwriters_stress=8
locktorture.stutter=0
locktorture.rt_boost=1
locktorture.rt_boost_factor=1
locktorture.nlocks=3

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-01-05 12:10:35 -08:00
Guo Ren
4282494a20 locking/qspinlock: Micro-optimize pending state waiting for unlock
When we're pending, we only care about lock value. The xchg_tail
wouldn't affect the pending state. That means the hardware thread
could stay in a sleep state and leaves the rest execution units'
resources of pipeline to other hardware threads. This situation is
the SMT scenarios in the same core. Not an entering low-power state
situation. Of course, the granularity between cores is "cacheline",
but the granularity between SMT hw threads of the same core could
be "byte" which internal LSU handles. For example, when a hw-thread
yields the resources of the core to other hw-threads, this patch
could help the hw-thread stay in the sleep state and prevent it
from being woken up by other hw-threads xchg_tail.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20230105021952.3090070-1-guoren@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
2023-01-05 11:01:50 +01:00
Linus Torvalds
95d248d16f - Prevent the leaking of a debug timer in futex_waitv()
- A preempt-RT mutex locking fix, adding the proper acquire semantics
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Merge tag 'locking_urgent_for_v6.2_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Borislav Petkov:

 - Prevent the leaking of a debug timer in futex_waitv()

 - A preempt-RT mutex locking fix, adding the proper acquire semantics

* tag 'locking_urgent_for_v6.2_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Fix futex_waitv() hrtimer debug object leak on kcalloc error
  rtmutex: Add acquire semantics for rtmutex lock acquisition slow path
2023-01-01 11:15:05 -08:00
Linus Torvalds
e2ca6ba6ba MM patches for 6.2-rc1.
- More userfaultfs work from Peter Xu.
 
 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying.
 
 - Some filemap cleanups from Vishal Moola.
 
 - David Hildenbrand added the ability to selftest anon memory COW handling.
 
 - Some cpuset simplifications from Liu Shixin.
 
 - Addition of vmalloc tracing support by Uladzislau Rezki.
 
 - Some pagecache folioifications and simplifications from Matthew Wilcox.
 
 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use it.
 
 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.  This series shold have been in the
   non-MM tree, my bad.
 
 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages.
 
 - DAMON cleanups and tuneups from SeongJae Park
 
 - Tony Luck fixed the handling of COW faults against poisoned pages.
 
 - Peter Xu utilized the PTE marker code for handling swapin errors.
 
 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient.
 
 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand.
 
 - zram support for multiple compression streams from Sergey Senozhatsky.
 
 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway.
 
 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations.
 
 - Vishal Moola removed the try_to_release_page() wrapper.
 
 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache.
 
 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking.
 
 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend.
 
 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range().
 
 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen.
 
 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests.  Better, but still not perfect.
 
 - Christoph Hellwig has removed the .writepage() method from several
   filesystems.  They only need .writepages().
 
 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting.
 
 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines.
 
 - Many singleton patches, as usual.
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Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - More userfaultfs work from Peter Xu

 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying

 - Some filemap cleanups from Vishal Moola

 - David Hildenbrand added the ability to selftest anon memory COW
   handling

 - Some cpuset simplifications from Liu Shixin

 - Addition of vmalloc tracing support by Uladzislau Rezki

 - Some pagecache folioifications and simplifications from Matthew
   Wilcox

 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
   it

 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.

   This series should have been in the non-MM tree, my bad

 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages

 - DAMON cleanups and tuneups from SeongJae Park

 - Tony Luck fixed the handling of COW faults against poisoned pages

 - Peter Xu utilized the PTE marker code for handling swapin errors

 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient

 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand

 - zram support for multiple compression streams from Sergey Senozhatsky

 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway

 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations

 - Vishal Moola removed the try_to_release_page() wrapper

 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache

 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking

 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend

 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range()

 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen

 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests. Better, but still not perfect

 - Christoph Hellwig has removed the .writepage() method from several
   filesystems. They only need .writepages()

 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting

 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines

 - Many singleton patches, as usual

* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
  mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
  mm: mmu_gather: allow more than one batch of delayed rmaps
  mm: fix typo in struct pglist_data code comment
  kmsan: fix memcpy tests
  mm: add cond_resched() in swapin_walk_pmd_entry()
  mm: do not show fs mm pc for VM_LOCKONFAULT pages
  selftests/vm: ksm_functional_tests: fixes for 32bit
  selftests/vm: cow: fix compile warning on 32bit
  selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
  mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
  mm,thp,rmap: fix races between updates of subpages_mapcount
  mm: memcg: fix swapcached stat accounting
  mm: add nodes= arg to memory.reclaim
  mm: disable top-tier fallback to reclaim on proactive reclaim
  selftests: cgroup: make sure reclaim target memcg is unprotected
  selftests: cgroup: refactor proactive reclaim code to reclaim_until()
  mm: memcg: fix stale protection of reclaim target memcg
  mm/mmap: properly unaccount memory on mas_preallocate() failure
  omfs: remove ->writepage
  jfs: remove ->writepage
  ...
2022-12-13 19:29:45 -08:00
Mel Gorman
1c0908d8e4 rtmutex: Add acquire semantics for rtmutex lock acquisition slow path
Jan Kara reported the following bug triggering on 6.0.5-rt14 running dbench
on XFS on arm64.

 kernel BUG at fs/inode.c:625!
 Internal error: Oops - BUG: 0 [#1] PREEMPT_RT SMP
 CPU: 11 PID: 6611 Comm: dbench Tainted: G            E   6.0.0-rt14-rt+ #1
 pc : clear_inode+0xa0/0xc0
 lr : clear_inode+0x38/0xc0
 Call trace:
  clear_inode+0xa0/0xc0
  evict+0x160/0x180
  iput+0x154/0x240
  do_unlinkat+0x184/0x300
  __arm64_sys_unlinkat+0x48/0xc0
  el0_svc_common.constprop.4+0xe4/0x2c0
  do_el0_svc+0xac/0x100
  el0_svc+0x78/0x200
  el0t_64_sync_handler+0x9c/0xc0
  el0t_64_sync+0x19c/0x1a0

It also affects 6.1-rc7-rt5 and affects a preempt-rt fork of 5.14 so this
is likely a bug that existed forever and only became visible when ARM
support was added to preempt-rt. The same problem does not occur on x86-64
and he also reported that converting sb->s_inode_wblist_lock to
raw_spinlock_t makes the problem disappear indicating that the RT spinlock
variant is the problem.

Which in turn means that RT mutexes on ARM64 and any other weakly ordered
architecture are affected by this independent of RT.

Will Deacon observed:

  "I'd be more inclined to be suspicious of the slowpath tbh, as we need to
   make sure that we have acquire semantics on all paths where the lock can
   be taken. Looking at the rtmutex code, this really isn't obvious to me
   -- for example, try_to_take_rt_mutex() appears to be able to return via
   the 'takeit' label without acquire semantics and it looks like we might
   be relying on the caller's subsequent _unlock_ of the wait_lock for
   ordering, but that will give us release semantics which aren't correct."

Sebastian Andrzej Siewior prototyped a fix that does work based on that
comment but it was a little bit overkill and added some fences that should
not be necessary.

The lock owner is updated with an IRQ-safe raw spinlock held, but the
spin_unlock does not provide acquire semantics which are needed when
acquiring a mutex.

Adds the necessary acquire semantics for lock owner updates in the slow path
acquisition and the waiter bit logic.

It successfully completed 10 iterations of the dbench workload while the
vanilla kernel fails on the first iteration.

[ bigeasy@linutronix.de: Initial prototype fix ]

Fixes: 700318d1d7 ("locking/rtmutex: Use acquire/release semantics")
Fixes: 23f78d4a03 ("[PATCH] pi-futex: rt mutex core")
Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221202100223.6mevpbl7i6x5udfd@techsingularity.net
2022-12-12 19:55:56 +01:00
Alexander Potapenko
1e8e4a7cc2 lockdep: allow instrumenting lockdep.c with KMSAN
Lockdep and KMSAN used to play badly together, causing deadlocks when
KMSAN instrumentation of lockdep.c called lockdep functions recursively.

Looks like this is no more the case, and a kernel can run (yet slower)
with both KMSAN and lockdep enabled.  This patch should fix false
positives on wq_head->lock->dep_map, which KMSAN used to consider
uninitialized because of lockdep.c not being instrumented.

Link: https://lore.kernel.org/lkml/Y3b9AAEKp2Vr3e6O@sol.localdomain/
Link: https://lkml.kernel.org/r/20221128094541.2645890-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-11 18:12:11 -08:00
Jason A. Donenfeld
8032bf1233 treewide: use get_random_u32_below() instead of deprecated function
This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-18 02:15:15 +01:00
Jason A. Donenfeld
81895a65ec treewide: use prandom_u32_max() when possible, part 1
Rather than incurring a division or requesting too many random bytes for
the given range, use the prandom_u32_max() function, which only takes
the minimum required bytes from the RNG and avoids divisions. This was
done mechanically with this coccinelle script:

@basic@
expression E;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
typedef u64;
@@
(
- ((T)get_random_u32() % (E))
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ((E) - 1))
+ prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2)
|
- ((u64)(E) * get_random_u32() >> 32)
+ prandom_u32_max(E)
|
- ((T)get_random_u32() & ~PAGE_MASK)
+ prandom_u32_max(PAGE_SIZE)
)

@multi_line@
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
identifier RAND;
expression E;
@@

-       RAND = get_random_u32();
        ... when != RAND
-       RAND %= (E);
+       RAND = prandom_u32_max(E);

// Find a potential literal
@literal_mask@
expression LITERAL;
type T;
identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32";
position p;
@@

        ((T)get_random_u32()@p & (LITERAL))

// Add one to the literal.
@script:python add_one@
literal << literal_mask.LITERAL;
RESULT;
@@

value = None
if literal.startswith('0x'):
        value = int(literal, 16)
elif literal[0] in '123456789':
        value = int(literal, 10)
if value is None:
        print("I don't know how to handle %s" % (literal))
        cocci.include_match(False)
elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1:
        print("Skipping 0x%x for cleanup elsewhere" % (value))
        cocci.include_match(False)
elif value & (value + 1) != 0:
        print("Skipping 0x%x because it's not a power of two minus one" % (value))
        cocci.include_match(False)
elif literal.startswith('0x'):
        coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1))
else:
        coccinelle.RESULT = cocci.make_expr("%d" % (value + 1))

// Replace the literal mask with the calculated result.
@plus_one@
expression literal_mask.LITERAL;
position literal_mask.p;
expression add_one.RESULT;
identifier FUNC;
@@

-       (FUNC()@p & (LITERAL))
+       prandom_u32_max(RESULT)

@collapse_ret@
type T;
identifier VAR;
expression E;
@@

 {
-       T VAR;
-       VAR = (E);
-       return VAR;
+       return E;
 }

@drop_var@
type T;
identifier VAR;
@@

 {
-       T VAR;
        ... when != VAR
 }

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap
Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:55 -06:00
Linus Torvalds
27bc50fc90 - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any negative
   reports (or any positive ones, come to that).
 
 - Also the Maple Tree from Liam R.  Howlett.  An overlapping range-based
   tree for vmas.  It it apparently slight more efficient in its own right,
   but is mainly targeted at enabling work to reduce mmap_lock contention.
 
   Liam has identified a number of other tree users in the kernel which
   could be beneficially onverted to mapletrees.
 
   Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
   (https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com).
   This has yet to be addressed due to Liam's unfortunately timed
   vacation.  He is now back and we'll get this fixed up.
 
 - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer.  It uses
   clang-generated instrumentation to detect used-unintialized bugs down to
   the single bit level.
 
   KMSAN keeps finding bugs.  New ones, as well as the legacy ones.
 
 - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
   memory into THPs.
 
 - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support
   file/shmem-backed pages.
 
 - userfaultfd updates from Axel Rasmussen
 
 - zsmalloc cleanups from Alexey Romanov
 
 - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure
 
 - Huang Ying adds enhancements to NUMA balancing memory tiering mode's
   page promotion, with a new way of detecting hot pages.
 
 - memcg updates from Shakeel Butt: charging optimizations and reduced
   memory consumption.
 
 - memcg cleanups from Kairui Song.
 
 - memcg fixes and cleanups from Johannes Weiner.
 
 - Vishal Moola provides more folio conversions
 
 - Zhang Yi removed ll_rw_block() :(
 
 - migration enhancements from Peter Xu
 
 - migration error-path bugfixes from Huang Ying
 
 - Aneesh Kumar added ability for a device driver to alter the memory
   tiering promotion paths.  For optimizations by PMEM drivers, DRM
   drivers, etc.
 
 - vma merging improvements from Jakub Matěn.
 
 - NUMA hinting cleanups from David Hildenbrand.
 
 - xu xin added aditional userspace visibility into KSM merging activity.
 
 - THP & KSM code consolidation from Qi Zheng.
 
 - more folio work from Matthew Wilcox.
 
 - KASAN updates from Andrey Konovalov.
 
 - DAMON cleanups from Kaixu Xia.
 
 - DAMON work from SeongJae Park: fixes, cleanups.
 
 - hugetlb sysfs cleanups from Muchun Song.
 
 - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
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Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
   linux-next for a couple of months without, to my knowledge, any
   negative reports (or any positive ones, come to that).

 - Also the Maple Tree from Liam Howlett. An overlapping range-based
   tree for vmas. It it apparently slightly more efficient in its own
   right, but is mainly targeted at enabling work to reduce mmap_lock
   contention.

   Liam has identified a number of other tree users in the kernel which
   could be beneficially onverted to mapletrees.

   Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
   at [1]. This has yet to be addressed due to Liam's unfortunately
   timed vacation. He is now back and we'll get this fixed up.

 - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
   clang-generated instrumentation to detect used-unintialized bugs down
   to the single bit level.

   KMSAN keeps finding bugs. New ones, as well as the legacy ones.

 - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
   memory into THPs.

 - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
   support file/shmem-backed pages.

 - userfaultfd updates from Axel Rasmussen

 - zsmalloc cleanups from Alexey Romanov

 - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
   memory-failure

 - Huang Ying adds enhancements to NUMA balancing memory tiering mode's
   page promotion, with a new way of detecting hot pages.

 - memcg updates from Shakeel Butt: charging optimizations and reduced
   memory consumption.

 - memcg cleanups from Kairui Song.

 - memcg fixes and cleanups from Johannes Weiner.

 - Vishal Moola provides more folio conversions

 - Zhang Yi removed ll_rw_block() :(

 - migration enhancements from Peter Xu

 - migration error-path bugfixes from Huang Ying

 - Aneesh Kumar added ability for a device driver to alter the memory
   tiering promotion paths. For optimizations by PMEM drivers, DRM
   drivers, etc.

 - vma merging improvements from Jakub Matěn.

 - NUMA hinting cleanups from David Hildenbrand.

 - xu xin added aditional userspace visibility into KSM merging
   activity.

 - THP & KSM code consolidation from Qi Zheng.

 - more folio work from Matthew Wilcox.

 - KASAN updates from Andrey Konovalov.

 - DAMON cleanups from Kaixu Xia.

 - DAMON work from SeongJae Park: fixes, cleanups.

 - hugetlb sysfs cleanups from Muchun Song.

 - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.

Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]

* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
  hugetlb: allocate vma lock for all sharable vmas
  hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
  hugetlb: fix vma lock handling during split vma and range unmapping
  mglru: mm/vmscan.c: fix imprecise comments
  mm/mglru: don't sync disk for each aging cycle
  mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
  mm: memcontrol: use do_memsw_account() in a few more places
  mm: memcontrol: deprecate swapaccounting=0 mode
  mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
  mm/secretmem: remove reduntant return value
  mm/hugetlb: add available_huge_pages() func
  mm: remove unused inline functions from include/linux/mm_inline.h
  selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
  selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
  selftests/vm: add thp collapse shmem testing
  selftests/vm: add thp collapse file and tmpfs testing
  selftests/vm: modularize thp collapse memory operations
  selftests/vm: dedup THP helpers
  mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
  mm/madvise: add file and shmem support to MADV_COLLAPSE
  ...
2022-10-10 17:53:04 -07:00
Linus Torvalds
3e71f0167b Locking changes for v6.1:
- Disable preemption in rwsem_write_trylock()'s attempt to
    take the rwsem, to avoid RT tasks hogging the CPU, which
    managed to preempt this function after the owner has
    been cleared but before a new owner is set. Also add
    debug checks to enforce this.
 
  - Add __lockfunc to more slow path functions and add
    __sched to semaphore functions.
 
  - Mark spinlock APIs noinline when the respective CONFIG_INLINE_SPIN_*
    toggles are disabled, to reduce LTO text size.
 
  - Print more debug information when lockdep gets confused
    in look_up_lock_class().
 
  - Improve header file abuse checks.
 
  - Misc cleanups
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

 - Disable preemption in rwsem_write_trylock()'s attempt to take the
   rwsem, to avoid RT tasks hogging the CPU, which managed to preempt
   this function after the owner has been cleared but before a new owner
   is set. Also add debug checks to enforce this.

 - Add __lockfunc to more slow path functions and add __sched to
   semaphore functions.

 - Mark spinlock APIs noinline when the respective CONFIG_INLINE_SPIN_*
   toggles are disabled, to reduce LTO text size.

 - Print more debug information when lockdep gets confused in
   look_up_lock_class().

 - Improve header file abuse checks.

 - Misc cleanups

* tag 'locking-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Print more debug information - report name and key when look_up_lock_class() got confused
  locking: Add __sched to semaphore functions
  locking/rwsem: Disable preemption while trying for rwsem lock
  locking: Detect includes rwlock.h outside of spinlock.h
  locking: Add __lockfunc to slow path functions
  locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabled
  selftests: futex: Fix 'the the' typo in comment
2022-10-10 09:44:12 -07:00
Alexander Potapenko
79dbd006a6 kmsan: disable instrumentation of unsupported common kernel code
EFI stub cannot be linked with KMSAN runtime, so we disable
instrumentation for it.

Instrumenting kcov, stackdepot or lockdep leads to infinite recursion
caused by instrumentation hooks calling instrumented code again.

Link: https://lkml.kernel.org/r/20220915150417.722975-13-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-10-03 14:03:20 -07:00
Tetsuo Handa
76e64c73db locking/lockdep: Print more debug information - report name and key when look_up_lock_class() got confused
Printing this information will be helpful:

  ------------[ cut here ]------------
  Looking for class "l2tp_sock" with key l2tp_socket_class, but found a different class "slock-AF_INET6" with the same key
  WARNING: CPU: 1 PID: 14195 at kernel/locking/lockdep.c:940 look_up_lock_class+0xcc/0x140
  Modules linked in:
  CPU: 1 PID: 14195 Comm: a.out Not tainted 6.0.0-rc6-dirty #863
  Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
  RIP: 0010:look_up_lock_class+0xcc/0x140

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/bd99391e-f787-efe9-5ec6-3c6dc4c587b0@I-love.SAKURA.ne.jp
2022-09-21 09:58:21 +02:00
Ingo Molnar
74656d03ac Linux 6.0-rc6
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Merge tag 'v6.0-rc6' into locking/core, to refresh the branch

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2022-09-21 09:58:02 +02:00
Namhyung Kim
0d97db0265 locking: Add __sched to semaphore functions
The internal functions are marked with __sched already, let's do the same
for external functions too so that we can skip them in the stack trace.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220909000803.4181857-1-namhyung@kernel.org
2022-09-15 16:14:03 +02:00
Gokul krishna Krishnakumar
48dfb5d256 locking/rwsem: Disable preemption while trying for rwsem lock
Make the region inside the rwsem_write_trylock non preemptible.

We observe RT task is hogging CPU when trying to acquire rwsem lock
which was acquired by a kworker task but before the rwsem owner was set.

Here is the scenario:
1. CFS task (affined to a particular CPU) takes rwsem lock.

2. CFS task gets preempted by a RT task before setting owner.

3. RT task (FIFO) is trying to acquire the lock, but spinning until
RT throttling happens for the lock as the lock was taken by CFS task.

This patch attempts to fix the above issue by disabling preemption
until owner is set for the lock. While at it also fix the issues
at the places where rwsem_{set,clear}_owner() are called.

This also adds lockdep annotation of preemption disable in
rwsem_{set,clear}_owner() on Peter Z. suggestion.

Signed-off-by: Gokul krishna Krishnakumar <quic_gokukris@quicinc.com>
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/1662661467-24203-1-git-send-email-quic_mojha@quicinc.com
2022-09-15 16:14:02 +02:00
Marco Elver
01fe8a3f81 locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked()
Implement simple accessors to probe percpu-rwsem's locked state:
percpu_is_write_locked(), percpu_is_read_locked().

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220829124719.675715-11-elver@google.com
2022-08-30 10:56:23 +02:00
Namhyung Kim
501f7f69bc locking: Add __lockfunc to slow path functions
So that we can skip the functions in the perf lock contention and other
places like /proc/PID/wchan.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20220810220346.1919485-1-namhyung@kernel.org
2022-08-19 19:47:51 +02:00
Andi Kleen
9aeaf5bc4e locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabled
Otherwise LTO will inline them anyways and cause a large kernel text increase.

Since the explicit intention here is to not inline them marking them noinline
is good documentation even for the non-LTO case.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Martin Liska <mliska@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220719110548.1544-1-jslaby@suse.cz
2022-08-04 11:05:43 +02:00
Linus Torvalds
7d9d077c78 RCU pull request for v5.20 (or whatever)
This pull request contains the following branches:
 
 doc.2022.06.21a: Documentation updates.
 
 fixes.2022.07.19a: Miscellaneous fixes.
 
 nocb.2022.07.19a: Callback-offload updates, perhaps most notably a new
 	RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to
 	be offloaded at boot time, regardless of kernel boot parameters.
 	This is useful to battery-powered systems such as ChromeOS
 	and Android.  In addition, a new RCU_NOCB_CPU_CB_BOOST kernel
 	boot parameter prevents offloaded callbacks from interfering
 	with real-time workloads and with energy-efficiency mechanisms.
 
 poll.2022.07.21a: Polled grace-period updates, perhaps most notably
 	making these APIs account for both normal and expedited grace
 	periods.
 
 rcu-tasks.2022.06.21a: Tasks RCU updates, perhaps most notably reducing
 	the CPU overhead of RCU tasks trace grace periods by more than
 	a factor of two on a system with 15,000 tasks.	The reduction
 	is expected to increase with the number of tasks, so it seems
 	reasonable to hypothesize that a system with 150,000 tasks might
 	see a 20-fold reduction in CPU overhead.
 
 torture.2022.06.21a: Torture-test updates.
 
 ctxt.2022.07.05a: Updates that merge RCU's dyntick-idle tracking into
 	context tracking, thus reducing the overhead of transitioning to
 	kernel mode from either idle or nohz_full userspace execution
 	for kernels that track context independently of RCU.  This is
 	expected to be helpful primarily for kernels built with
 	CONFIG_NO_HZ_FULL=y.
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Merge tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU updates from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes

 - Callback-offload updates, perhaps most notably a new
   RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be
   offloaded at boot time, regardless of kernel boot parameters.

   This is useful to battery-powered systems such as ChromeOS and
   Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot
   parameter prevents offloaded callbacks from interfering with
   real-time workloads and with energy-efficiency mechanisms

 - Polled grace-period updates, perhaps most notably making these APIs
   account for both normal and expedited grace periods

 - Tasks RCU updates, perhaps most notably reducing the CPU overhead of
   RCU tasks trace grace periods by more than a factor of two on a
   system with 15,000 tasks.

   The reduction is expected to increase with the number of tasks, so it
   seems reasonable to hypothesize that a system with 150,000 tasks
   might see a 20-fold reduction in CPU overhead

 - Torture-test updates

 - Updates that merge RCU's dyntick-idle tracking into context tracking,
   thus reducing the overhead of transitioning to kernel mode from
   either idle or nohz_full userspace execution for kernels that track
   context independently of RCU.

   This is expected to be helpful primarily for kernels built with
   CONFIG_NO_HZ_FULL=y

* tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits)
  rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings
  rcu: Diagnose extended sync_rcu_do_polled_gp() loops
  rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings
  rcutorture: Test polled expedited grace-period primitives
  rcu: Add polled expedited grace-period primitives
  rcutorture: Verify that polled GP API sees synchronous grace periods
  rcu: Make Tiny RCU grace periods visible to polled APIs
  rcu: Make polled grace-period API account for expedited grace periods
  rcu: Switch polled grace-period APIs to ->gp_seq_polled
  rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty
  rcu/nocb: Add option to opt rcuo kthreads out of RT priority
  rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread()
  rcu/nocb: Add an option to offload all CPUs on boot
  rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call
  rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order
  rcu/nocb: Add/del rdp to iterate from rcuog itself
  rcu/tree: Add comment to describe GP-done condition in fqs loop
  rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs()
  rcu/kvfree: Remove useless monitor_todo flag
  rcu: Cleanup RCU urgency state for offline CPU
  ...
2022-08-02 19:12:45 -07:00
Linus Torvalds
22a39c3d86 This was a fairly quiet cycle for the locking subsystem:
- lockdep: Fix a handful of the more complex lockdep_init_map_*() primitives
    that can lose the lock_type & cause false reports. No such mishap was
    observed in the wild.
 
  - jump_label improvements: simplify the cross-arch support of
    initial NOP patching by making it arch-specific code (used on MIPS only),
    and remove the s390 initial NOP patching that was superfluous.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "This was a fairly quiet cycle for the locking subsystem:

   - lockdep: Fix a handful of the more complex lockdep_init_map_*()
     primitives that can lose the lock_type & cause false reports. No
     such mishap was observed in the wild.

   - jump_label improvements: simplify the cross-arch support of initial
     NOP patching by making it arch-specific code (used on MIPS only),
     and remove the s390 initial NOP patching that was superfluous"

* tag 'locking-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Fix lockdep_init_map_*() confusion
  jump_label: make initial NOP patching the special case
  jump_label: mips: move module NOP patching into arch code
  jump_label: s390: avoid pointless initial NOP patching
2022-08-01 12:15:27 -07:00