Linus,
Please pull the latest locking/urgent Git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking-urgent-2025-11-08
# HEAD: 4cb5ac2626b5704ed712ac1d46b9d89fdfc12c5d futex: Optimize per-cpu reference counting
Fix (well, cut in half) a futex performance regression on PowerPC.
Thanks,
Ingo
------------------>
Peter Zijlstra (1):
futex: Optimize per-cpu reference counting
kernel/futex/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 125804fbb5cb..2e77a6e5c865 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1680,10 +1680,10 @@ static bool futex_ref_get(struct futex_private_hash *fph)
{
struct mm_struct *mm = fph->mm;
- guard(rcu)();
+ guard(preempt)();
- if (smp_load_acquire(&fph->state) == FR_PERCPU) {
- this_cpu_inc(*mm->futex_ref);
+ if (READ_ONCE(fph->state) == FR_PERCPU) {
+ __this_cpu_inc(*mm->futex_ref);
return true;
}
@@ -1694,10 +1694,10 @@ static bool futex_ref_put(struct futex_private_hash *fph)
{
struct mm_struct *mm = fph->mm;
- guard(rcu)();
+ guard(preempt)();
- if (smp_load_acquire(&fph->state) == FR_PERCPU) {
- this_cpu_dec(*mm->futex_ref);
+ if (READ_ONCE(fph->state) == FR_PERCPU) {
+ __this_cpu_dec(*mm->futex_ref);
return false;
}