This is a note to let you know that I've just added the patch titled
timers: Add missing READ_ONCE() in __run_timer_base()
to the 6.12-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:
timers-add-missing-read_once-in-__run_timer_base.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f62c348949866c1c11f9b484aa652c4f2cb4745e
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed Oct 30 08:53:51 2024 +0100
timers: Add missing READ_ONCE() in __run_timer_base()
[ Upstream commit 1d4199cbbe95efaba51304cfd844bd0ccd224e61 ]
__run_timer_base() checks base::next_expiry without holding
base::lock. That can race with a remote CPU updating next_expiry under the
lock. This is an intentional and harmless data race, but lacks a
READ_ONCE(), so KCSAN complains about this.
Add the missing READ_ONCE(). All other places are covered already.
Fixes: 79f8b28e85f8 ("timers: Annotate possible non critical data race of next_expiry")
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/all/87a5emyqk0.ffs@tglx
Closes: https://lore.kernel.org/oe-lkp/202410301205.ef8e9743-lkp@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 0fc9d066a7be4..7835f9b376e76 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -2422,7 +2422,8 @@ static inline void __run_timers(struct timer_base *base)
static void __run_timer_base(struct timer_base *base)
{
- if (time_before(jiffies, base->next_expiry))
+ /* Can race against a remote CPU updating next_expiry under the lock */
+ if (time_before(jiffies, READ_ONCE(base->next_expiry)))
return;
timer_base_lock_expiry(base);
