From: Gaurav Kohli <gkohli@codeaurora.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Qian Cai <cai@lca.pw>,
akpm@linux-foundation.org, hch@lst.de, mingo@redhat.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] block: fix a crash in do_task_dead()
Date: Tue, 11 Jun 2019 10:09:06 +0530 [thread overview]
Message-ID: <154008a8-9d29-2411-28a0-0284a95b4481@codeaurora.org> (raw)
In-Reply-To: <20190610144641.GA8127@redhat.com>
>>> +
>>
>> Hi Peter, Jen,
>>
>> As we are not taking pi_lock here , is there possibility of same task dead
>> call comes as this point of time for current thread, bcoz of which we have
>> seen earlier issue after this commit 0619317ff8ba
>> [T114538] do_task_dead+0xf0/0xf8
>> [T114538] do_exit+0xd5c/0x10fc
>> [T114538] do_group_exit+0xf4/0x110
>> [T114538] get_signal+0x280/0xdd8
>> [T114538] do_notify_resume+0x720/0x968
>> [T114538] work_pending+0x8/0x10
>>
>> Is there a chance of TASK_DEAD set at this point of time?
>
> In this case try_to_wake_up(current, TASK_NORMAL) will do nothing, see the
> if (!(p->state & state)) above.
>
> See also the comment about set_special_state() above. It disables irqs and
> this is enough to ensure that try_to_wake_up(current) from irq can't race
> with set_special_state(TASK_DEAD).
Thanks Oleg,
I missed that part(both thread and interrupt is in same core only), So
that situation would never come.
>
> Oleg.
>
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2019-06-11 4:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-29 20:25 [PATCH] block: fix a crash in do_task_dead() Qian Cai
2019-05-29 20:31 ` Jens Axboe
2019-05-30 8:03 ` Peter Zijlstra
2019-05-31 21:12 ` Jens Axboe
2019-06-03 12:37 ` Peter Zijlstra
2019-06-03 12:44 ` Peter Zijlstra
2019-06-03 16:09 ` Oleg Nesterov
2019-06-03 16:19 ` Peter Zijlstra
2019-06-03 16:23 ` Jens Axboe
2019-06-05 15:04 ` Jens Axboe
2019-06-07 13:35 ` Peter Zijlstra
2019-06-07 14:23 ` Peter Zijlstra
2019-06-08 8:39 ` Jens Axboe
2019-06-10 13:13 ` Gaurav Kohli
2019-06-10 14:46 ` Oleg Nesterov
2019-06-11 4:39 ` Gaurav Kohli [this message]
2019-06-30 23:06 ` Hugh Dickins
2019-07-01 14:22 ` Jens Axboe
2019-07-02 22:06 ` Andrew Morton
2019-07-03 17:35 ` Oleg Nesterov
2019-07-03 17:44 ` Hugh Dickins
2019-07-04 16:00 ` Oleg Nesterov
2019-07-03 17:52 ` Jens Axboe
2019-05-30 11:15 ` Oleg Nesterov
2019-05-31 21:10 ` Jens Axboe
2019-07-04 16:03 ` [PATCH] swap_readpage: avoid blk_wake_io_task() if !synchronous Oleg Nesterov
2019-07-04 19:32 ` Andrew Morton
2019-07-04 21:15 ` Hugh Dickins
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