linux-kernel - Re: [PATCH] fs: process fput task_work with TWA

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Message-ID: <6fdffaf6-2a40-da4f-217d-157f163111cb@kernel.dk>
Date:   Thu, 7 Jan 2021 20:52:22 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Doug Anderson <dianders@...omium.org>
Cc:     linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Oleg Nesterov <oleg@...hat.com>,
        Song Liu <songliubraving@...com>
Subject: Re: [PATCH] fs: process fput task_work with TWA_SIGNAL

On 1/7/21 3:17 PM, Doug Anderson wrote:
> Hi,
> 
> On Tue, Jan 5, 2021 at 10:30 AM Jens Axboe <axboe@...nel.dk> wrote:
>>
>> Song reported a boot regression in a kvm image with 5.11-rc, and bisected
>> it down to the below patch. Debugging this issue, turns out that the boot
>> stalled when a task is waiting on a pipe being released. As we no longer
>> run task_work from get_signal() unless it's queued with TWA_SIGNAL, the
>> task goes idle without running the task_work. This prevents ->release()
>> from being called on the pipe, which another boot task is waiting on.
>>
>> Use TWA_SIGNAL for the file fput work to ensure it's run before the task
>> goes idle.
>>
>> Fixes: 98b89b649fce ("signal: kill JOBCTL_TASK_WORK")
>> Reported-by: Song Liu <songliubraving@...com>
>> Signed-off-by: Jens Axboe <axboe@...nel.dk>
> 
> I just spend a bit of time bisecting and landed on commit 98b89b649fce
> ("signal: kill JOBCTL_TASK_WORK") causing my failure to bootup
> mainline.  Your patch fixes my problem.  I haven't done any analysis
> of the code--just testing, thus:
> 
> Tested-by: Douglas Anderson <dianders@...omium.org>

Thanks, adding your Tested-by.

-- 
Jens Axboe