From: Jens Axboe <[email protected]>
To: Peter Zijlstra <[email protected]>
Cc: [email protected], [email protected], [email protected]
Subject: Re: [PATCH 6/9] sched: add a sched_work list
Date: Thu, 20 Feb 2020 13:53:33 -0800 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 2/20/20 2:17 PM, Peter Zijlstra wrote:
> On Thu, Feb 20, 2020 at 01:31:48PM -0700, Jens Axboe wrote:
>> This is similar to the task_works, and uses the same infrastructure, but
>> the sched_work list is run when the task is being scheduled in or out.
>>
>> The intended use case here is for core code to be able to add work
>> that should be automatically run by the task, without the task needing
>> to do anything. This is done outside of the task, one example would be
>> from waitqueue handlers, or anything else that is invoked out-of-band
>> from the task itself.
>>
>
>
>> diff --git a/kernel/task_work.c b/kernel/task_work.c
>> index 3445421266e7..ba62485d5b3d 100644
>> --- a/kernel/task_work.c
>> +++ b/kernel/task_work.c
>> @@ -3,7 +3,14 @@
>> #include <linux/task_work.h>
>> #include <linux/tracehook.h>
>>
>> -static struct callback_head work_exited; /* all we need is ->next == NULL */
>> +static void task_exit_func(struct callback_head *head)
>> +{
>> +}
>> +
>> +static struct callback_head work_exited = {
>> + .next = NULL,
>> + .func = task_exit_func,
>> +};
>
> Do we really need this? It seems to suggest we're trying to execute
> work_exited, which would be an error.
>
> Doing so would be the result of calling sched_work_run() after
> exit_task_work(). I suppose that's actually possible.. the problem is
> that that would reset sched_work to NULL and re-allow queueing works,
> which would then leak.
>
> I'll look at it in more detail tomorrow, I'm tired...
Let me try and instrument it, I definitely hit it on task exit
but might have been induced by some earlier bugs.
--
Jens Axboe
next prev parent reply other threads:[~2020-02-20 21:53 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 20:31 [PATCHSET 0/9] io_uring: use polled async retry Jens Axboe
2020-02-20 20:31 ` [PATCH 1/9] io_uring: consider any io_read/write -EAGAIN as final Jens Axboe
2020-02-20 20:31 ` [PATCH 2/9] io_uring: io_accept() should hold on to submit reference on retry Jens Axboe
2020-02-20 20:31 ` [PATCH 3/9] sched: move io-wq/workqueue worker sched in/out into helpers Jens Axboe
2020-02-20 20:31 ` [PATCH 4/9] task_work_run: don't take ->pi_lock unconditionally Jens Axboe
2020-02-20 20:31 ` [PATCH 5/9] kernel: abstract out task work helpers Jens Axboe
2020-02-20 21:07 ` Peter Zijlstra
2020-02-20 21:08 ` Jens Axboe
2020-02-20 20:31 ` [PATCH 6/9] sched: add a sched_work list Jens Axboe
2020-02-20 21:17 ` Peter Zijlstra
2020-02-20 21:53 ` Jens Axboe [this message]
2020-02-20 22:02 ` Jens Axboe
2020-02-20 20:31 ` [PATCH 7/9] io_uring: add per-task callback handler Jens Axboe
2020-02-20 22:02 ` Jann Horn
2020-02-20 22:14 ` Jens Axboe
2020-02-20 22:18 ` Jens Axboe
2020-02-20 22:25 ` Jann Horn
2020-02-20 22:23 ` Jens Axboe
2020-02-20 22:38 ` Jann Horn
2020-02-20 22:56 ` Jens Axboe
2020-02-20 22:58 ` Jann Horn
2020-02-20 23:02 ` Jens Axboe
2020-02-20 22:23 ` Jann Horn
2020-02-20 23:00 ` Jens Axboe
2020-02-20 23:12 ` Jann Horn
2020-02-20 23:22 ` Jens Axboe
2020-02-21 1:29 ` Jann Horn
2020-02-21 17:32 ` Jens Axboe
2020-02-21 19:24 ` Jann Horn
2020-02-21 20:18 ` Jens Axboe
2020-02-20 22:56 ` Jann Horn
2020-02-21 10:47 ` Peter Zijlstra
2020-02-21 14:49 ` Jens Axboe
2020-02-21 15:02 ` Jann Horn
2020-02-21 16:12 ` Peter Zijlstra
2020-02-21 16:23 ` Peter Zijlstra
2020-02-21 20:13 ` Jens Axboe
2020-02-21 13:51 ` Pavel Begunkov
2020-02-21 14:50 ` Jens Axboe
2020-02-21 18:30 ` Pavel Begunkov
2020-02-21 19:10 ` Jens Axboe
2020-02-21 19:22 ` Pavel Begunkov
2020-02-23 6:00 ` Jens Axboe
2020-02-23 6:26 ` Jens Axboe
2020-02-23 11:02 ` Pavel Begunkov
2020-02-23 14:49 ` Jens Axboe
2020-02-23 14:58 ` Jens Axboe
2020-02-23 15:07 ` Jens Axboe
2020-02-23 18:04 ` Pavel Begunkov
2020-02-23 18:06 ` Jens Axboe
2020-02-23 17:55 ` Pavel Begunkov
2020-02-20 20:31 ` [PATCH 8/9] io_uring: mark requests that we can do poll async in io_op_defs Jens Axboe
2020-02-20 20:31 ` [PATCH 9/9] io_uring: use poll driven retry for files that support it Jens Axboe
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