From: Zqiang qiang.zhang@windriver.com
commit 6993d0fdbee0eb38bfac350aa016f65ad11ed3b1 upstream.
There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn:
CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work();
BUG: kthread_insert_work() should not get called when work->canceling is set.
Signed-off-by: Zqiang qiang.zhang@windriver.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: Petr Mladek pmladek@suse.com Acked-by: Tejun Heo tj@kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -897,7 +897,8 @@ void kthread_delayed_work_timer_fn(struc /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list);
raw_spin_unlock_irqrestore(&worker->lock, flags); }