From: Oleg Nesterov <oleg@redhat.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: [RFC] exit: do exit_task_work() before shooting off mm
Date: Sun, 20 Dec 2020 14:58:03 +0100 [thread overview]
Message-ID: <20201220135803.GA16470@redhat.com> (raw)
In-Reply-To: <ce5be208-99eb-f7bd-e602-9361008ff83c@gmail.com>
On 12/20, Pavel Begunkov wrote:
>
> On 08/12/2020 01:37, Al Viro wrote:
> > On Thu, Dec 03, 2020 at 02:30:46AM +0000, Pavel Begunkov wrote:
> >> Handle task works and lock it earlier before it starts killing off
> >> task's resources like mm. io_uring makes use of it a lot and it'd
> >> nicer to have all added task_work finding tasks in a consistent state.
I too do not understand this patch. task_work_add() will fail after
exit_task_work(). This means that, for example, exit_files() will use
schedule_delayed_work().
> One more moment, after we've set PF_EXITING any task_work_run() would be
> equivalent to exit_task_work()
Yes, currently task_work_run() can not be called after exit_signals().
And shouldn't be called imo ;)
> io_uring
> may want (currently doesn't) to run works for cancellation purposes.
Please see https://lore.kernel.org/io-uring/20200407163816.GB9655@redhat.com/
> Shouldn't it be like below (not tested)? Also simplifies task_work_run().
I'd prefer the patch from the link above, but your version looks correct too.
However, I still think it would be better to not abuse task_work_run() too
much...
Oleg.
next prev parent reply other threads:[~2020-12-20 13:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 2:30 [RFC] exit: do exit_task_work() before shooting off mm Pavel Begunkov
2020-12-08 1:37 ` Al Viro
2020-12-08 3:00 ` Pavel Begunkov
2020-12-20 12:50 ` Pavel Begunkov
2020-12-20 13:58 ` Oleg Nesterov [this message]
2020-12-20 14:42 ` Pavel Begunkov
2020-12-14 14:51 ` [exit] 80fae08355: stderr.mount:/fs/sda1:/dev/sda1_already_mounted_or_mount_point_busy kernel test robot
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