Linus,
Please pull the latest locking/urgent Git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking-urgent-2026-08-08
# HEAD: 8e7ff730dd96519a333d1570edf1c3fabb6d3629 futex: Fix race in futex_pivot_pending() during private hash resize
- Fix race in futex_pivot_pending() during private hash resize
that can cause stuck tasks (Yao Kai)
Thanks,
Ingo
------------------>
Yao Kai (1):
futex: Fix race in futex_pivot_pending() during private hash resize
kernel/futex/core.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 2650d1e52803..128c5752f225 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -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);
}