linux-kernel - Re: [PATCH v2 1/2] kthread: allocate kthread structure using kmalloc

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Message-ID: <CALCETrU-ZC4vGrC3WXSS7OguROxCzpY=egHh+eY5T5Fmtv20=g@mail.gmail.com>
Date:   Mon, 24 Oct 2016 10:08:20 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Roman Pen <roman.penyaev@...fitbricks.com>
Cc:     Andy Lutomirski <luto@...nel.org>, Oleg Nesterov <oleg@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Tejun Heo <tj@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] kthread: allocate kthread structure using kmalloc

On Mon, Oct 24, 2016 at 9:08 AM, Roman Pen
<roman.penyaev@...fitbricks.com> wrote:
> This patch avoids allocation of kthread structure on a stack, and simply
> uses kmalloc.  Allocation on a stack became a huge problem (with memory
> corruption and all other not nice consequences) after the commit 2deb4be28
> by Andy Lutomirski, which rewinds the stack on oops, thus ooopsed kthread
> steps on a garbage memory while completion of task->vfork_done structure
> on the following path:

This is IMO a *huge* improvement.

Shouldn't the patch also remove the try_get_task_stack() /
put_task_stack() hackery in kthread.c, though?