From 4db4b1a0d1779dc159f7b87feb97030ec0b12597 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xmission.com> Date: Sun, 21 Mar 2021 09:37:48 -0600 Subject: [PATCH] signal: don't allow STOP on PF_IO_WORKER threads Just like we don't allow normal signals to IO threads, don't deliver a STOP to a task that has PF_IO_WORKER set. The IO threads don't take signals in general, and have no means of flushing out a stop either. Longer term, we may want to look into allowing stop of these threads, as it relates to eg process freezing. For now, this prevents a spin issue if a SIGSTOP is delivered to the parent task. Reported-by: Stefan Metzmacher <metze@samba.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- kernel/signal.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/signal.c b/kernel/signal.c index 11cabcf20e7a..f2a1b898da29 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -288,7 +288,8 @@ bool task_set_jobctl_pending(struct task_struct *task, unsigned long mask) JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING)); BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK)); - if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING))) + if (unlikely(fatal_signal_pending(task) || + (task->flags & (PF_EXITING | PF_IO_WORKER)))) return false; if (mask & JOBCTL_STOP_SIGMASK)