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Date: Mon, 1 Feb 2016 14:46:17 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>, Richard Weinberger <richard@nod.at>,
        "Amanieu d'Antras" <amanieu@gmail.com>,
        Chris Metcalf <cmetcalf@ezchip.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Vladimir Davydov <vdavydov@parallels.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: WARNING in set_restore_sigmask
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On Fri, 29 Jan 2016 15:13:47 +0100 Oleg Nesterov <oleg@redhat.com> wrote:

> On 01/29, Dmitry Vyukov wrote:
> >
> > Hello,
> >
> > I've got the following WARNING while running syzkaller fuzzer:
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 2 PID: 10905 at ./arch/x86/include/asm/thread_info.h:236
> > sigsuspend+0x18e/0x1f0()
> > Modules linked in:
> > CPU: 2 PID: 10905 Comm: syz-executor Not tainted 4.5.0-rc1+ #300
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >  00000000ffffffff ffff88006139fe38 ffffffff82be118d 0000000000000000
> >  ffff88006d054740 ffffffff867387e0 ffff88006139fe78 ffffffff813536d9
> >  ffffffff813839ce ffffffff867387e0 00000000000000ec 0000000020000000
> > Call Trace:
> >  [<     inline     >] __dump_stack lib/dump_stack.c:15
> >  [<ffffffff82be118d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
> >  [<ffffffff813536d9>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
> >  [<ffffffff81353909>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
> >  [<     inline     >] set_restore_sigmask
> > ./arch/x86/include/asm/thread_info.h:236
> >  [<ffffffff813839ce>] sigsuspend+0x18e/0x1f0 kernel/signal.c:3513
> 
> See http://marc.info/?t=145373722000004 the patch is already in -mm tree.

I'll get this into 4.5 as we now appear to have some code which actually
triggers it.

I wonder where that wakeup is coming from.