[PATCH v4 0/2] futex: Address two futex-requeue-pi issues

[Sebastian Andrzej Siewior]

This is an update to Yao Kai initial series. I replaced #1 and updated the
commit a bit in #2.
 
#1 Was simply missed in the initial commit and never noticed.
#2 Requires extreme precise timing to reproduce.

v3…4: https://lore.kernel.org/all/20260824125544.2353006-1-bigeasy@xxxxxxxxxxxxx/
 - PeterZ pointed out that doing sched_submit_work() while waiter is enqueued
   looks a bit wrong. tglx's enthusiasm was also missing.
   Rewrote that bit to only trigger the assert.
 
v2…v3: https://lore.kernel.org/20260722085140.1949077-1-yaokai34@xxxxxxxxxx
 - Update commit message for both patches.
 - Drop the comment from #1. The whole thing has nothing to do with
   skipped schedule(). The only problem is that that rt_mutex_schedule()
   requires a rt_mutex_.*_schedule() invocation before rtmutex is about
   to be acquired. In case it went unnoticed for so long because that
   rt_mutex is usually not contended.
 - Update the comment in #2 to describe the race and why the wake is
   skipped.
 
v1…v2: (Yao Kai) https://lore.kernel.org/20260722085140.1949077-1-yaokai34@xxxxxxxxxx
 - Replace the scheduler helper split in patch 1 with
   rt_mutex_pre_schedule()/rt_mutex_post_schedule() directly around
   rt_mutex_wait_proxy_lock().
 - Expand patch 2's comment and changelog to explain why the saved-task
   wakeup covers rcuwait without losing a wakeup.

Sebastian Andrzej Siewior (1):
  futex: Provide rt_mutex_.*_schedule() equivalents for futex scheduling

Yao Kai (1):
  futex: Prevent rcuwait use-after-free during requeue PI

 include/linux/sched/rt.h     |  2 ++
 kernel/futex/pi.c            | 16 +++-------------
 kernel/futex/requeue.c       | 12 ++++++++++--
 kernel/locking/rtmutex_api.c |  2 ++
 kernel/sched/core.c          | 16 ++++++++++++++++
 5 files changed, 33 insertions(+), 15 deletions(-)

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2.55.0