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Merge tag 'locking-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull locking fix from Ingo Molnar:
 "Fix lockup in requeue-PI during signal/timeout wakeups, by Sebastian
  Andrzej Siewior"

* tag 'locking-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Prevent lockup in requeue-PI during signal/ timeout wakeup
This commit is contained in:
Linus Torvalds
2026-05-03 08:17:09 -07:00
parent c3cba36b39 bc7304f3ae
commit cffcf520fd
1 changed files with 9 additions and 4 deletions
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13
kernel/futex/requeue.c
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@@ -319,8 +319,11 @@ futex_proxy_trylock_atomic(u32 __user *pifutex, struct futex_hash_bucket *hb1,
return -EINVAL;
/* Ensure that this does not race against an early wakeup */
if (!futex_requeue_pi_prepare(top_waiter, NULL))
if (!futex_requeue_pi_prepare(top_waiter, NULL)) {
plist_del(&top_waiter->list, &hb1->chain);
futex_hb_waiters_dec(hb1);
return -EAGAIN;
}
/*
* Try to take the lock for top_waiter and set the FUTEX_WAITERS bit
@@ -722,10 +725,12 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
/*
* We were woken prior to requeue by a timeout or a signal.
* Unqueue the futex_q and determine which it was.
* Conditionally unqueue the futex_q and determine which it was.
*/
plist_del(&q->list, &hb->chain);
futex_hb_waiters_dec(hb);
if (!plist_node_empty(&q->list)) {
plist_del(&q->list, &hb->chain);
futex_hb_waiters_dec(hb);
}
/* Handle spurious wakeups gracefully */
ret = -EWOULDBLOCK;