Hello,
On 10/21/19 10:35 AM, kernel test robot wrote:
FYI, we noticed the following commit (built with gcc-7):
commit: 6394de3b868537a90dd9128607192b0e97109f6b ("[PATCH 4/5] ipc/sem.c: Document
and update memory barriers")
url:
https://github.com/0day-ci/linux/commits/Manfred-Spraul/wake_q-Cleanup-Documentation-update/20191014-055627
Yes, known issue:
@@ -2148,9 +2176,11 @@ static long do_semtimedop(int semid, struct
sembuf __user *tsops,
}
do {
- WRITE_ONCE(queue.status, -EINTR);
+ /* memory ordering ensured by the lock in sem_lock() */
+ queue.status = EINTR;
queue.sleeper = current;
+ /* memory ordering is ensured by the lock in sem_lock() */
__set_current_state(TASK_INTERRUPTIBLE);
sem_unlock(sma, locknum);
rcu_read_unlock();
It must be "-EINTR", not "EINTR".
If there is a timeout or a spurious wakeup, then the do_semtimedop()
returns to user space without unlinking everything properly.
I was able to reproduce the issue: V1 of the series ends up with the
shown error.
V3 as now merged doesn't fail.
--
Manfred
