Am 25.03.21 um 13:04 schrieb Eric W. Biederman:
Stefan Metzmacher metze@samba.org writes:
Am 25.03.21 um 12:24 schrieb Sasha Levin:
From: "Eric W. Biederman" ebiederm@xmission.com
[ Upstream commit 4db4b1a0d1779dc159f7b87feb97030ec0b12597 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org
kernel/signal.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/signal.c b/kernel/signal.c index 55526b941011..00a3840f6037 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))))if (mask & JOBCTL_STOP_SIGMASK)
Again, why is this proposed for 5.11 and 5.10 already?
Has the bit about the io worker kthreads been backported? If so this isn't horrible. If not this is nonsense.
I don't know, I hope not...
But I just tested v5.12-rc4 and attaching to an application with iothreads with gdb is still not possible, it still loops forever trying to attach to the iothreads.
And I tested 'kill -9 $pidofiothread', and it feezed the whole machine...
So there's still work to do in order to get 5.12 stable.
I'm short on time currently, but I hope to send more details soon.
metze