futex fix

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(-)

index 2650d1e52803..128c5752f225 100644
@@ -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);
 }