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- Fix race in futex_pivot_pending() during private hash resize

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that can cause stuck tasks (Yao Kai)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-urgent-2026-08-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull futex fix from Ingo Molnar:

 - Fix race in futex_pivot_pending() during private hash resize
   that can cause stuck tasks (Yao Kai)

* tag 'locking-urgent-2026-08-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Fix race in futex_pivot_pending() during private hash resize
This commit is contained in:
Linus Torvalds 2026-08-08 16:39:53 -07:00
commit d4eee3bdb8
1 changed files with 4 additions and 3 deletions
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7
kernel/futex/core.c
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@ -1783,14 +1783,15 @@ void futex_hash_free(struct mm_struct *mm)
static bool futex_pivot_pending(struct mm_struct *mm)
{
struct futex_mm_phash *mmph = &mm->futex.phash;
struct futex_private_hash *fph;
guard(rcu)();
guard(mutex)(&mmph->lock);
if (!mm->futex.phash.hash_new)
if (!mmph->hash_new)
return true;
fph = rcu_dereference(mm->futex.phash.hash);
fph = rcu_dereference_raw(mmph->hash);
return futex_ref_is_dead(fph);
}