From: Jens Axboe <axboe@kernel.dk>
To: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Cc: Pavel Begunkov <asml.silence@gmail.com>,
io-uring Mailing List <io-uring@vger.kernel.org>,
Bedirhan KURT <windowz414@gnuweeb.org>
Subject: Re: [PATCH v6 liburing] test: Add kworker-hang test
Date: Tue, 9 Nov 2021 07:47:34 -0700 [thread overview]
Message-ID: <ede7d490-4e48-7acf-725a-161e350e39a0@kernel.dk> (raw)
In-Reply-To: <CAGzmLMWsFYe3VJLonr7dc6Z3qe7YoB8b1meX6hyiHQdacpzBtw@mail.gmail.com>
On 11/8/21 10:44 PM, Ammar Faizi wrote:
> On Sat, Nov 6, 2021 at 6:49 PM Ammar Faizi wrote:
>>
>> This is the reproducer for the kworker hang bug.
>>
>> Reproduction Steps:
>> 1) A user task calls io_uring_queue_exit().
>>
>> 2) Suspend the task with SIGSTOP / SIGTRAP before the ring exit is
>> finished (do it as soon as step (1) is done).
>>
>> 3) Wait for `/proc/sys/kernel/hung_task_timeout_secs` seconds
>> elapsed.
>>
>> 4) We get a complaint from the khungtaskd because the kworker is
>> stuck in an uninterruptible state (D).
>>
>> The kworkers waiting on ring exit are not progressing as the task
>> cannot proceed. When the user task is continued (e.g. get SIGCONT
>> after SIGSTOP, or continue after SIGTRAP breakpoint), the kworkers
>> then can finish the ring exit.
>>
>> We need a special handling for this case to avoid khungtaskd
>> complaint. Currently we don't have the fix for this.
> [...]
>> Cc: Pavel Begunkov <asml.silence@gmail.com>
>> Link: https://github.com/axboe/liburing/issues/448
>> Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
>> ---
>>
>> v6:
>> - Fix missing call to restore_hung_entries() when fork() fails.
>>
>> .gitignore | 1 +
>> test/Makefile | 1 +
>> test/kworker-hang.c | 323 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 325 insertions(+)
>> create mode 100644 test/kworker-hang.c
>
> It's ready for review.
This one is still triggering in the current tree, I'd prefer waiting with
queueing it up until it's fixed. I can park it in another branch until
that happens.
--
Jens Axboe
next prev parent reply other threads:[~2021-11-09 14:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 19:07 [PATCH liburing] test: Add kworker-hang test Ammar Faizi
2021-10-20 12:51 ` [PATCH v2 " Ammar Faizi
2021-11-05 23:35 ` Ammar Faizi
2021-11-05 23:41 ` Jens Axboe
2021-11-06 0:58 ` [PATCH v3 " Ammar Faizi
2021-11-06 7:42 ` [PATCH v4 " Ammar Faizi
2021-11-06 11:37 ` [PATCH v5 " Ammar Faizi
2021-11-06 11:49 ` [PATCH v6 " Ammar Faizi
2021-11-09 5:44 ` Ammar Faizi
2021-11-09 14:47 ` Jens Axboe [this message]
2021-11-09 15:21 ` Ammar Faizi
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