Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'locking-urgent-2026-05-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
+9
-4
+9
-4
kernel/futex/requeue.c
+9
-4
kernel/futex/requeue.c
···
319
319
return -EINVAL;
320
320
321
321
/* Ensure that this does not race against an early wakeup */
322
-
if (!futex_requeue_pi_prepare(top_waiter, NULL))
322
+
if (!futex_requeue_pi_prepare(top_waiter, NULL)) {
323
+
plist_del(&top_waiter->list, &hb1->chain);
324
+
futex_hb_waiters_dec(hb1);
323
325
return -EAGAIN;
326
+
}
324
327
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328
/*
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329
* Try to take the lock for top_waiter and set the FUTEX_WAITERS bit
···
725
722
726
723
/*
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724
* We were woken prior to requeue by a timeout or a signal.
728
-
* Unqueue the futex_q and determine which it was.
725
+
* Conditionally unqueue the futex_q and determine which it was.
729
726
*/
730
-
plist_del(&q->list, &hb->chain);
731
-
futex_hb_waiters_dec(hb);
727
+
if (!plist_node_empty(&q->list)) {
728
+
plist_del(&q->list, &hb->chain);
729
+
futex_hb_waiters_dec(hb);
730
+
}
732
731
733
732
/* Handle spurious wakeups gracefully */
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733
ret = -EWOULDBLOCK;