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

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Message-ID: <CA+icZUV2jRPtKyTw7h-mST83yooTdOLYRBWcoLFgUSjtcUMVgg@mail.gmail.com>
Date:   Fri, 8 Jan 2021 07:20:57 +0100
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Doug Anderson <dianders@...omium.org>,
        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 Fri, Jan 8, 2021 at 4:56 AM Jens Axboe <axboe@...nel.dk> wrote:
>
> 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.
>

I have this in my patch-series since it appeared in [1].

Feel free to add my:

   Tested-by: Sedat Dilek <sedat.dilek@...il.com> # LLVM/Clang version 11.0.1

- Sedat -

[1] https://git.kernel.dk/cgit/linux-block/log/?h=task_work

- Sedat -