The following commit has been merged into the timers/core branch of tip:
Commit-ID: f99c5bb396b8d1424ed229d1ffa6f596e3b9c36b
Gitweb: https://git.kernel.org/tip/f99c5bb396b8d1424ed229d1ffa6f596e3b9c36b
Author: Benjamin Segall <bsegall@xxxxxxxxxx>
AuthorDate: Fri, 14 Feb 2025 14:12:20 -08:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 18 Feb 2025 10:12:49 +01:00
posix-timers: Invoke cond_resched() during exit_itimers()
exit_itimers() loops through every timer in the process to delete it. This
requires taking the system-wide hash_lock for each of these timers, and
contends with other processes trying to create or delete timers.
When a process creates hundreds of thousands of timers, and then exits
while other processes contend with it, this can trigger softlockups on
CONFIG_PREEMPT=n.
Add a cond_resched() invocation into the loop to allow the system to make
progress.
Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/xm2634gg2n23.fsf@xxxxxxxxxx
---
kernel/time/posix-timers.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 1b675ae..44ba7db 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1099,8 +1099,10 @@ void exit_itimers(struct task_struct *tsk)
spin_unlock_irq(&tsk->sighand->siglock);
/* The timers are not longer accessible via tsk::signal */
- while (!hlist_empty(&timers))
+ while (!hlist_empty(&timers)) {
itimer_delete(hlist_entry(timers.first, struct k_itimer, list));
+ cond_resched();
+ }
/*
* There should be no timers on the ignored list. itimer_delete() has
|