From: Jens Axboe <axboe@kernel.dk>
To: Hillf Danton <hdanton@sina.com>
Cc: io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
viro@zeniv.linux.org.uk,
syzbot+107dd59d1efcaf3ffca4@syzkaller.appspotmail.com,
Stefano Garzarella <sgarzare@redhat.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH next] io_uring: fix task hung in io_uring_setup
Date: Thu, 3 Sep 2020 08:04:22 -0600 [thread overview]
Message-ID: <9bef23b1-6791-6601-4368-93de53212b22@kernel.dk> (raw)
In-Reply-To: <20200903132119.14564-1-hdanton@sina.com>
On 9/3/20 7:21 AM, Hillf Danton wrote:
>
> The smart syzbot found the following issue:
>
> INFO: task syz-executor047:6853 blocked for more than 143 seconds.
> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
> Call Trace:
> context_switch kernel/sched/core.c:3777 [inline]
> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
> do_wait_for_common kernel/sched/completion.c:85 [inline]
> __wait_for_common kernel/sched/completion.c:106 [inline]
> wait_for_common kernel/sched/completion.c:117 [inline]
> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
> io_sq_thread_stop fs/io_uring.c:6906 [inline]
> io_finish_async fs/io_uring.c:6920 [inline]
> io_sq_offload_create fs/io_uring.c:7595 [inline]
> io_uring_create fs/io_uring.c:8671 [inline]
> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> because the sqo_thread kthread is created in io_sq_offload_create() without
> being waked up. Then in the error branch of that function we will wait for
> the sqo kthread that never runs. It's fixed by waking it up before waiting.
Looks good - applied, thanks.
--
Jens Axboe
next parent reply other threads:[~2020-09-03 14:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200903132119.14564-1-hdanton@sina.com>
2020-09-03 14:04 ` Jens Axboe [this message]
2020-09-07 8:50 ` [PATCH next] io_uring: fix task hung in io_uring_setup Pavel Begunkov
2020-09-07 12:55 ` Jens Axboe
[not found] ` <20200908000339.2260-1-hdanton@sina.com>
2020-09-08 20:58 ` Pavel Begunkov
2020-09-08 23:34 ` Jens Axboe
[not found] ` <20200909001943.18916-1-hdanton@sina.com>
2020-09-09 14:24 ` Jens Axboe
2020-09-07 8:43 ` Stefano Garzarella
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