linux-stable.git/kernel/sched/core.c, branch linux-6.11.y Linux kernel stable tree sched/core: Disable page allocation in task_tick_mm_cid() 2024-11-01T01:02:25+00:00 Waiman Long longman@redhat.com 2024-10-10T01:44:32+00:00 ce0241ef83eed55f675376e8a3605d23de53d875 [ Upstream commit 73ab05aa46b02d96509cb029a8d04fca7bbde8c7 ] With KASAN and PREEMPT_RT enabled, calling task_work_add() in task_tick_mm_cid() may cause the following splat. [ 63.696416] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 [ 63.696416] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 610, name: modprobe [ 63.696416] preempt_count: 10001, expected: 0 [ 63.696416] RCU nest depth: 1, expected: 1 This problem is caused by the following call trace. sched_tick() [ acquire rq->__lock ] -> task_tick_mm_cid() -> task_work_add() -> __kasan_record_aux_stack() -> kasan_save_stack() -> stack_depot_save_flags() -> alloc_pages_mpol_noprof() -> __alloc_pages_noprof() -> get_page_from_freelist() -> rmqueue() -> rmqueue_pcplist() -> __rmqueue_pcplist() -> rmqueue_bulk() -> rt_spin_lock() The rq lock is a raw_spinlock_t. We can't sleep while holding it. IOW, we can't call alloc_pages() in stack_depot_save_flags(). The task_tick_mm_cid() function with its task_work_add() call was introduced by commit 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid") in v6.4 kernel. Fortunately, there is a kasan_record_aux_stack_noalloc() variant that calls stack_depot_save_flags() while not allowing it to allocate new pages. To allow task_tick_mm_cid() to use task_work without page allocation, a new TWAF_NO_ALLOC flag is added to enable calling kasan_record_aux_stack_noalloc() instead of kasan_record_aux_stack() if set. The task_tick_mm_cid() function is modified to add this new flag. The possible downside is the missing stack trace in a KASAN report due to new page allocation required when task_work_add_noallloc() is called which should be rare. Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20241010014432.194742-1-longman@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 73ab05aa46b02d96509cb029a8d04fca7bbde8c7 ]

With KASAN and PREEMPT_RT enabled, calling task_work_add() in
task_tick_mm_cid() may cause the following splat.

[   63.696416] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
[   63.696416] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 610, name: modprobe
[   63.696416] preempt_count: 10001, expected: 0
[   63.696416] RCU nest depth: 1, expected: 1

This problem is caused by the following call trace.

  sched_tick() [ acquire rq->__lock ]
   -> task_tick_mm_cid()
    -> task_work_add()
     -> __kasan_record_aux_stack()
      -> kasan_save_stack()
       -> stack_depot_save_flags()
        -> alloc_pages_mpol_noprof()
         -> __alloc_pages_noprof()
	  -> get_page_from_freelist()
	   -> rmqueue()
	    -> rmqueue_pcplist()
	     -> __rmqueue_pcplist()
	      -> rmqueue_bulk()
	       -> rt_spin_lock()

The rq lock is a raw_spinlock_t. We can't sleep while holding
it. IOW, we can't call alloc_pages() in stack_depot_save_flags().

The task_tick_mm_cid() function with its task_work_add() call was
introduced by commit 223baf9d17f2 ("sched: Fix performance regression
introduced by mm_cid") in v6.4 kernel.

Fortunately, there is a kasan_record_aux_stack_noalloc() variant that
calls stack_depot_save_flags() while not allowing it to allocate
new pages.  To allow task_tick_mm_cid() to use task_work without
page allocation, a new TWAF_NO_ALLOC flag is added to enable calling
kasan_record_aux_stack_noalloc() instead of kasan_record_aux_stack()
if set. The task_tick_mm_cid() function is modified to add this new flag.

The possible downside is the missing stack trace in a KASAN report due
to new page allocation required when task_work_add_noallloc() is called
which should be rare.

Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241010014432.194742-1-longman@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
sched/core: Clear prev->dl_server in CFS pick fast path 2024-10-10T10:03:57+00:00 Youssef Esmat youssefesmat@google.com 2024-05-27T12:06:49+00:00 782d5a758dcee9a032fcdb044182b19c3825189d commit a741b82423f41501e301eb6f9820b45ca202e877 upstream. In case the previous pick was a DL server pick, ->dl_server might be set. Clear it in the fast path as well. Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers") Signed-off-by: Youssef Esmat <youssefesmat@google.com> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Juri Lelli <juri.lelli@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/7f7381ccba09efcb4a1c1ff808ed58385eccc222.1716811044.git.bristot@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a741b82423f41501e301eb6f9820b45ca202e877 upstream.

In case the previous pick was a DL server pick, ->dl_server might be
set. Clear it in the fast path as well.

Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Youssef Esmat <youssefesmat@google.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/7f7381ccba09efcb4a1c1ff808ed58385eccc222.1716811044.git.bristot@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sched/core: Add clearing of ->dl_server in put_prev_task_balance() 2024-10-10T10:03:57+00:00 Joel Fernandes (Google) joel@joelfernandes.org 2024-05-27T12:06:48+00:00 6cdec86523c126d018759658f64a8633f4e43242 commit c245910049d04fbfa85bb2f5acd591c24e9907c7 upstream. Paths using put_prev_task_balance() need to do a pick shortly after. Make sure they also clear the ->dl_server on prev as a part of that. Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers") Signed-off-by: "Joel Fernandes (Google)" <joel@joelfernandes.org> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Juri Lelli <juri.lelli@redhat.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/d184d554434bedbad0581cb34656582d78655150.1716811044.git.bristot@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit c245910049d04fbfa85bb2f5acd591c24e9907c7 upstream.

Paths using put_prev_task_balance() need to do a pick shortly
after. Make sure they also clear the ->dl_server on prev as a
part of that.

Fixes: 63ba8422f876 ("sched/deadline: Introduce deadline servers")
Signed-off-by: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/d184d554434bedbad0581cb34656582d78655150.1716811044.git.bristot@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sched/core: Fix unbalance set_rq_online/offline() in sched_cpu_deactivate() 2024-07-29T10:22:33+00:00 Yang Yingliang yangyingliang@huawei.com 2024-07-03T03:16:10+00:00 fe7a11c78d2a9bdb8b50afc278a31ac177000948 If cpuset_cpu_inactive() fails, set_rq_online() need be called to rollback. Fixes: 120455c514f7 ("sched: Fix hotplug vs CPU bandwidth control") Cc: stable@kernel.org Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240703031610.587047-5-yangyingliang@huaweicloud.com 
If cpuset_cpu_inactive() fails, set_rq_online() need be called to rollback.

Fixes: 120455c514f7 ("sched: Fix hotplug vs CPU bandwidth control")
Cc: stable@kernel.org
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240703031610.587047-5-yangyingliang@huaweicloud.com
sched/core: Introduce sched_set_rq_on/offline() helper 2024-07-29T10:22:32+00:00 Yang Yingliang yangyingliang@huawei.com 2024-07-03T03:16:09+00:00 2f027354122f58ee846468a6f6b48672fff92e9b Introduce sched_set_rq_on/offline() helper, so it can be called in normal or error path simply. No functional changed. Cc: stable@kernel.org Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240703031610.587047-4-yangyingliang@huaweicloud.com 
Introduce sched_set_rq_on/offline() helper, so it can be called
in normal or error path simply. No functional changed.

Cc: stable@kernel.org
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240703031610.587047-4-yangyingliang@huaweicloud.com
sched/smt: Fix unbalance sched_smt_present dec/inc 2024-07-29T10:22:32+00:00 Yang Yingliang yangyingliang@huawei.com 2024-07-03T03:16:08+00:00 e22f910a26cc2a3ac9c66b8e935ef2a7dd881117 I got the following warn report while doing stress test: jump label: negative count! WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0 Call Trace: <TASK> __static_key_slow_dec_cpuslocked+0x16/0x70 sched_cpu_deactivate+0x26e/0x2a0 cpuhp_invoke_callback+0x3ad/0x10d0 cpuhp_thread_fun+0x3f5/0x680 smpboot_thread_fn+0x56d/0x8d0 kthread+0x309/0x400 ret_from_fork+0x41/0x70 ret_from_fork_asm+0x1b/0x30 </TASK> Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(), the cpu offline failed, but sched_smt_present is decremented before calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so fix it by incrementing sched_smt_present in the error path. Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology") Cc: stable@kernel.org Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Chen Yu <yu.c.chen@intel.com> Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> Link: https://lore.kernel.org/r/20240703031610.587047-3-yangyingliang@huaweicloud.com 
I got the following warn report while doing stress test:

jump label: negative count!
WARNING: CPU: 3 PID: 38 at kernel/jump_label.c:263 static_key_slow_try_dec+0x9d/0xb0
Call Trace:
 <TASK>
 __static_key_slow_dec_cpuslocked+0x16/0x70
 sched_cpu_deactivate+0x26e/0x2a0
 cpuhp_invoke_callback+0x3ad/0x10d0
 cpuhp_thread_fun+0x3f5/0x680
 smpboot_thread_fn+0x56d/0x8d0
 kthread+0x309/0x400
 ret_from_fork+0x41/0x70
 ret_from_fork_asm+0x1b/0x30
 </TASK>

Because when cpuset_cpu_inactive() fails in sched_cpu_deactivate(),
the cpu offline failed, but sched_smt_present is decremented before
calling sched_cpu_deactivate(), it leads to unbalanced dec/inc, so
fix it by incrementing sched_smt_present in the error path.

Fixes: c5511d03ec09 ("sched/smt: Make sched_smt_present track topology")
Cc: stable@kernel.org
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Link: https://lore.kernel.org/r/20240703031610.587047-3-yangyingliang@huaweicloud.com
sched/smt: Introduce sched_smt_present_inc/dec() helper 2024-07-29T10:22:32+00:00 Yang Yingliang yangyingliang@huawei.com 2024-07-03T03:16:07+00:00 31b164e2e4af84d08d2498083676e7eeaa102493 Introduce sched_smt_present_inc/dec() helper, so it can be called in normal or error path simply. No functional changed. Cc: stable@kernel.org Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240703031610.587047-2-yangyingliang@huaweicloud.com 
Introduce sched_smt_present_inc/dec() helper, so it can be called
in normal or error path simply. No functional changed.

Cc: stable@kernel.org
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240703031610.587047-2-yangyingliang@huaweicloud.com
sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24T18:59:29+00:00 Joel Granados j.granados@samsung.com 2024-07-24T18:59:29+00:00 78eb4ea25cd5fdbdae7eb9fdf87b99195ff67508 const qualify the struct ctl_table argument in the proc_handler function signatures. This is a prerequisite to moving the static ctl_table structs into .rodata data which will ensure that proc_handler function pointers cannot be modified. This patch has been generated by the following coccinelle script: ``` virtual patch @r1@ identifier ctl, write, buffer, lenp, ppos; identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)"; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos); @r2@ identifier func, ctl, write, buffer, lenp, ppos; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos) { ... } @r3@ identifier func; @@ int func( - struct ctl_table * + const struct ctl_table * ,int , void *, size_t *, loff_t *); @r4@ identifier func, ctl; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int , void *, size_t *, loff_t *); @r5@ identifier func, write, buffer, lenp, ppos; @@ int func( - struct ctl_table * + const struct ctl_table * ,int write, void *buffer, size_t *lenp, loff_t *ppos); ``` * Code formatting was adjusted in xfs_sysctl.c to comply with code conventions. The xfs_stats_clear_proc_handler, xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where adjusted. * The ctl_table argument in proc_watchdog_common was const qualified. This is called from a proc_handler itself and is calling back into another proc_handler, making it necessary to change it as part of the proc_handler migration. Co-developed-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Co-developed-by: Joel Granados <j.granados@samsung.com> Signed-off-by: Joel Granados <j.granados@samsung.com> 
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
Merge tag 'sched-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2024-07-17T00:00:50+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-07-17T00:00:50+00:00 4a996d90b9e046c6d59845acf00a54d464c34ff3 Pull scheduler updates from Ingo Molnar: - Update Daniel Bristot de Oliveira's entry in MAINTAINERS, and credit him in CREDITS - Harmonize the lock-yielding behavior on dynamically selected preemption models with static ones - Reorganize the code a bit: split out sched/syscalls.c to reduce the size of sched/core.c - Micro-optimize psi_group_change() - Fix set_load_weight() for SCHED_IDLE tasks - Misc cleanups & fixes * tag 'sched-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Update MAINTAINERS and CREDITS sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks sched/psi: Optimise psi_group_change a bit sched/core: Drop spinlocks on contention iff kernel is preemptible sched/core: Move preempt_model_*() helpers from sched.h to preempt.h sched/balance: Skip unnecessary updates to idle load balancer's flags idle: Remove stale RCU comment sched/headers: Move struct pre-declarations to the beginning of the header sched/core: Clean up kernel/sched/sched.h a bit sched/core: Simplify prefetch_curr_exec_start() sched: Fix spelling in comments sched/syscalls: Split out kernel/sched/syscalls.c from kernel/sched/core.c 
Pull scheduler updates from Ingo Molnar:

 - Update Daniel Bristot de Oliveira's entry in MAINTAINERS,
   and credit him in CREDITS

 - Harmonize the lock-yielding behavior on dynamically selected
   preemption models with static ones

 - Reorganize the code a bit: split out sched/syscalls.c to reduce
   the size of sched/core.c

 - Micro-optimize psi_group_change()

 - Fix set_load_weight() for SCHED_IDLE tasks

 - Misc cleanups & fixes

* tag 'sched-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Update MAINTAINERS and CREDITS
  sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks
  sched/psi: Optimise psi_group_change a bit
  sched/core: Drop spinlocks on contention iff kernel is preemptible
  sched/core: Move preempt_model_*() helpers from sched.h to preempt.h
  sched/balance: Skip unnecessary updates to idle load balancer's flags
  idle: Remove stale RCU comment
  sched/headers: Move struct pre-declarations to the beginning of the header
  sched/core: Clean up kernel/sched/sched.h a bit
  sched/core: Simplify prefetch_curr_exec_start()
  sched: Fix spelling in comments
  sched/syscalls: Split out kernel/sched/syscalls.c from kernel/sched/core.c
Merge tag 'rcu.2024.07.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu 2024-07-15T22:25:27+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-07-15T22:25:27+00:00 9855e873285f1395b9a04613c56101f04a5ec9fb Pull RCU updates from Paul McKenney: - Update Tasks RCU and Tasks Rude RCU description in Requirements.rst and clarify rcu_assign_pointer() and rcu_dereference() ordering properties - Add lockdep assertions for RCU readers, limit inline wakeups for callback-bypass synchronize_rcu(), add an rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter, add Uladzislau Rezki as RCU maintainer, and fix a subtle callback-migration memory-ordering issue - Remove a number of redundant memory barriers - Remove unnecessary bypass-list lock-contention mitigation, use parking API instead of open-coded ad-hoc equivalent, and upgrade obsolete comments - Revert avoidance of a deadlock that can no longer occur and properly synchronize Tasks Trace RCU checking of runqueues - Add tests for handling of double-call_rcu() bug, add missing MODULE_DESCRIPTION, and add a script that histograms the number of calls to RCU updaters - Fill out SRCU polled-grace-period API * tag 'rcu.2024.07.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits) rcu: Fix rcu_barrier() VS post CPUHP_TEARDOWN_CPU invocation rcu: Eliminate lockless accesses to rcu_sync->gp_count MAINTAINERS: Add Uladzislau Rezki as RCU maintainer rcu: Add rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter rcu/exp: Remove redundant full memory barrier at the end of GP rcu: Remove full memory barrier on RCU stall printout rcu: Remove full memory barrier on boot time eqs sanity check rcu/exp: Remove superfluous full memory barrier upon first EQS snapshot rcu: Remove superfluous full memory barrier upon first EQS snapshot rcu: Remove full ordering on second EQS snapshot srcu: Fill out polled grace-period APIs srcu: Update cleanup_srcu_struct() comment srcu: Add NUM_ACTIVE_SRCU_POLL_OLDSTATE srcu: Disable interrupts directly in srcu_gp_end() rcu: Disable interrupts directly in rcu_gp_init() rcu/tree: Reduce wake up for synchronize_rcu() common case rcu/tasks: Fix stale task snaphot for Tasks Trace tools/rcu: Add rcu-updaters.sh script rcutorture: Add missing MODULE_DESCRIPTION() macros rcutorture: Fix rcu_torture_fwd_cb_cr() data race ... 
Pull RCU updates from Paul McKenney:

 - Update Tasks RCU and Tasks Rude RCU description in Requirements.rst
   and clarify rcu_assign_pointer() and rcu_dereference() ordering
   properties

 - Add lockdep assertions for RCU readers, limit inline wakeups for
   callback-bypass synchronize_rcu(), add an
   rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter, add
   Uladzislau Rezki as RCU maintainer, and fix a subtle
   callback-migration memory-ordering issue

 - Remove a number of redundant memory barriers

 - Remove unnecessary bypass-list lock-contention mitigation, use
   parking API instead of open-coded ad-hoc equivalent, and upgrade
   obsolete comments

 - Revert avoidance of a deadlock that can no longer occur and properly
   synchronize Tasks Trace RCU checking of runqueues

 - Add tests for handling of double-call_rcu() bug, add missing
   MODULE_DESCRIPTION, and add a script that histograms the number of
   calls to RCU updaters

 - Fill out SRCU polled-grace-period API

* tag 'rcu.2024.07.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits)
  rcu: Fix rcu_barrier() VS post CPUHP_TEARDOWN_CPU invocation
  rcu: Eliminate lockless accesses to rcu_sync->gp_count
  MAINTAINERS: Add Uladzislau Rezki as RCU maintainer
  rcu: Add rcutree.nohz_full_patience_delay to reduce nohz_full OS jitter
  rcu/exp: Remove redundant full memory barrier at the end of GP
  rcu: Remove full memory barrier on RCU stall printout
  rcu: Remove full memory barrier on boot time eqs sanity check
  rcu/exp: Remove superfluous full memory barrier upon first EQS snapshot
  rcu: Remove superfluous full memory barrier upon first EQS snapshot
  rcu: Remove full ordering on second EQS snapshot
  srcu: Fill out polled grace-period APIs
  srcu: Update cleanup_srcu_struct() comment
  srcu: Add NUM_ACTIVE_SRCU_POLL_OLDSTATE
  srcu: Disable interrupts directly in srcu_gp_end()
  rcu: Disable interrupts directly in rcu_gp_init()
  rcu/tree: Reduce wake up for synchronize_rcu() common case
  rcu/tasks: Fix stale task snaphot for Tasks Trace
  tools/rcu: Add rcu-updaters.sh script
  rcutorture: Add missing MODULE_DESCRIPTION() macros
  rcutorture: Fix rcu_torture_fwd_cb_cr() data race
  ...