This is a note to let you know that I've just added the patch titled
locking/rtmutex: Fix incorrect condition in rtmutex_spin_on_owner()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
locking-rtmutex-fix-incorrect-condition-in-rtmutex_spin_on_owner.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8f556a326c93213927e683fc32bbf5be1b62540a Mon Sep 17 00:00:00 2001
From: Zqiang <qiang1.zhang@xxxxxxxxx>
Date: Fri, 17 Dec 2021 15:42:07 +0800
Subject: locking/rtmutex: Fix incorrect condition in rtmutex_spin_on_owner()
From: Zqiang <qiang1.zhang@xxxxxxxxx>
commit 8f556a326c93213927e683fc32bbf5be1b62540a upstream.
Optimistic spinning needs to be terminated when the spinning waiter is not
longer the top waiter on the lock, but the condition is negated. It
terminates if the waiter is the top waiter, which is defeating the whole
purpose.
Fixes: c3123c431447 ("locking/rtmutex: Dont dereference waiter lockless")
Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20211217074207.77425-1-qiang1.zhang@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/locking/rtmutex.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1373,7 +1373,7 @@ static bool rtmutex_spin_on_owner(struct
* - the VCPU on which owner runs is preempted
*/
if (!owner->on_cpu || need_resched() ||
- rt_mutex_waiter_is_top_waiter(lock, waiter) ||
+ !rt_mutex_waiter_is_top_waiter(lock, waiter) ||
vcpu_is_preempted(task_cpu(owner))) {
res = false;
break;
Patches currently in stable-queue which might be from qiang1.zhang@xxxxxxxxx are
queue-5.15/locking-rtmutex-fix-incorrect-condition-in-rtmutex_spin_on_owner.patch
