From: Jens Axboe <[email protected]>
To: Stefan Metzmacher <[email protected]>, [email protected]
Cc: [email protected], [email protected],
[email protected]
Subject: Re: [PATCH 09/18] io-wq: fork worker threads from original task
Date: Thu, 4 Mar 2021 06:05:31 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 3/4/21 5:23 AM, Stefan Metzmacher wrote:
>
> Hi Jens,
>
>> +static pid_t fork_thread(int (*fn)(void *), void *arg)
>> +{
>> + unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
>> + CLONE_IO|SIGCHLD;
>> + struct kernel_clone_args args = {
>> + .flags = ((lower_32_bits(flags) | CLONE_VM |
>> + CLONE_UNTRACED) & ~CSIGNAL),
>> + .exit_signal = (lower_32_bits(flags) & CSIGNAL),
>> + .stack = (unsigned long)fn,
>> + .stack_size = (unsigned long)arg,
>> + };
>> +
>> + return kernel_clone(&args);
>> +}
>
> Can you please explain why CLONE_SIGHAND is used here?
We can't have CLONE_THREAD without CLONE_SIGHAND... The io-wq workers
don't really care about signals, we don't use them internally.
> Will the userspace signal handlers executed from the kernel thread?
No
> Will SIGCHLD be posted to the userspace signal handlers in a userspace
> process? Will wait() from userspace see the exit of a thread?
Currently actually it does, but I think that's just an oversight. As far
as I can tell, we want to add something like the below. Untested... I'll
give this a spin in a bit.
diff --git a/kernel/signal.c b/kernel/signal.c
index ba4d1ef39a9e..e5db1d8f18e5 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1912,6 +1912,10 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
bool autoreap = false;
u64 utime, stime;
+ /* Don't notify a parent task if an io_uring worker exits */
+ if (tsk->flags & PF_IO_WORKER)
+ return true;
+
BUG_ON(sig == -1);
/* do_notify_parent_cldstop should have been called instead. */
--
Jens Axboe
next prev parent reply other threads:[~2021-03-04 13:06 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 17:09 [PATCHSET RFC 0/18] Remove kthread usage from io_uring Jens Axboe
2021-02-19 17:09 ` [PATCH 01/18] io_uring: remove the need for relying on an io-wq fallback worker Jens Axboe
2021-02-19 20:25 ` Eric W. Biederman
2021-02-19 20:37 ` Jens Axboe
2021-02-22 13:46 ` Pavel Begunkov
2021-02-19 17:09 ` [PATCH 02/18] io-wq: don't create any IO workers upfront Jens Axboe
2021-02-19 17:09 ` [PATCH 03/18] io_uring: disable io-wq attaching Jens Axboe
2021-02-19 17:09 ` [PATCH 04/18] io-wq: get rid of wq->use_refs Jens Axboe
2021-02-19 17:09 ` [PATCH 05/18] io_uring: tie async worker side to the task context Jens Axboe
2021-02-20 8:11 ` Hao Xu
2021-02-20 14:38 ` Jens Axboe
2021-02-21 9:16 ` Hao Xu
2021-02-19 17:09 ` [PATCH 06/18] io-wq: don't pass 'wqe' needlessly around Jens Axboe
2021-02-19 17:09 ` [PATCH 07/18] arch: setup PF_IO_WORKER threads like PF_KTHREAD Jens Axboe
2021-02-19 22:21 ` Eric W. Biederman
2021-02-19 23:26 ` Jens Axboe
2021-02-19 17:10 ` [PATCH 08/18] kernel: treat PF_IO_WORKER like PF_KTHREAD for ptrace/signals Jens Axboe
2021-02-19 17:10 ` [PATCH 09/18] io-wq: fork worker threads from original task Jens Axboe
2021-03-04 12:23 ` Stefan Metzmacher
2021-03-04 13:05 ` Jens Axboe [this message]
2021-03-04 13:19 ` Stefan Metzmacher
2021-03-04 16:13 ` Stefan Metzmacher
2021-03-04 16:42 ` Jens Axboe
2021-03-04 17:09 ` Stefan Metzmacher
2021-03-04 17:32 ` Jens Axboe
2021-03-04 18:19 ` Jens Axboe
2021-03-04 18:56 ` Linus Torvalds
2021-03-04 19:19 ` Jens Axboe
2021-03-04 19:46 ` Linus Torvalds
2021-03-04 19:54 ` Jens Axboe
2021-03-04 20:00 ` Jens Axboe
2021-03-04 20:23 ` Jens Axboe
2021-03-04 20:50 ` Linus Torvalds
2021-03-04 20:54 ` Jens Axboe
2021-03-05 19:16 ` Eric W. Biederman
2021-03-05 19:00 ` Eric W. Biederman
2021-02-19 17:10 ` [PATCH 10/18] io-wq: worker idling always returns false Jens Axboe
2021-02-19 17:10 ` [PATCH 11/18] io_uring: remove any grabbing of context Jens Axboe
2021-02-19 17:10 ` [PATCH 12/18] io_uring: remove io_identity Jens Axboe
2021-02-19 17:10 ` [PATCH 13/18] io-wq: only remove worker from free_list, if it was there Jens Axboe
2021-02-19 17:10 ` [PATCH 14/18] io-wq: make io_wq_fork_thread() available to other users Jens Axboe
2021-02-19 17:10 ` [PATCH 15/18] io_uring: move SQPOLL thread io-wq forked worker Jens Axboe
2021-02-19 17:10 ` [PATCH 16/18] Revert "proc: don't allow async path resolution of /proc/thread-self components" Jens Axboe
2021-02-19 17:10 ` [PATCH 17/18] Revert "proc: don't allow async path resolution of /proc/self components" Jens Axboe
2021-02-19 17:10 ` [PATCH 18/18] net: remove cmsg restriction from io_uring based send/recvmsg calls Jens Axboe
2021-02-19 23:44 ` [PATCHSET RFC 0/18] Remove kthread usage from io_uring Stefan Metzmacher
2021-02-19 23:51 ` Jens Axboe
2021-02-21 5:04 ` Linus Torvalds
2021-02-21 21:22 ` Jens Axboe
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