Re: WARNING: CPU: 12 PID: 16862 at ./arch/x86/include/asm/thread_info.h:236

From	Oleg Nesterov <oleg@redhat.com>
Newsgroups	linux.kernel
Subject	Re: WARNING: CPU: 12 PID: 16862 at ./arch/x86/include/asm/thread_info.h:236
Date	2015-11-30 19:50 +0100
Message-ID	<qABGq-7gu-23@gated-at.bofh.it> (permalink)
References	<qAzuW-5YC-27@gated-at.bofh.it> <qAzOi-66r-25@gated-at.bofh.it> <qAzXY-69w-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 11/30, Peter Zijlstra wrote:
>
> On Mon, Nov 30, 2015 at 04:44:05PM +0000, Al Viro wrote:
> > On Mon, Nov 30, 2015 at 11:20:44AM -0500, Sasha Levin wrote:
> > > Hi all,
> > >
> > > I've hit the following while fuzzing with trinity on the latest -next kernel:
> >
> >         __set_current_state(TASK_INTERRUPTIBLE);
> >         schedule();
> >         set_restore_sigmask();
> >
> > somehow got out of schedule() without TIF_SIGPENDING being set...
>
> A random wakeup (which are always possible) can make that happen, right?

Yes, sigsuspend() should do "while (!signal_pending(current))". Like
sys_pause() does, -ERESTARTNOHAND without signal_pending() is equally
wrong.

I'll send the fix unless Sasha wants to do this.

> I'm (as always) a little vague on signals, but who is responsible for
> setting that bit?

See above, TS_RESTORE_SIGMASK doesn't differ from -ERESTART* in that
you can only use it if signal_pending() is true.

Oleg.

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WARNING: CPU: 12 PID: 16862 at  ./arch/x86/include/asm/thread_info.h:236 Sasha Levin <sasha.levin@oracle.com> - 2015-11-30 17:30 +0100
  Re: WARNING: CPU: 12 PID: 16862 at  ./arch/x86/include/asm/thread_info.h:236 Al Viro <viro@ZenIV.linux.org.uk> - 2015-11-30 17:50 +0100
    Re: WARNING: CPU: 12 PID: 16862 at  ./arch/x86/include/asm/thread_info.h:236 Peter Zijlstra <peterz@infradead.org> - 2015-11-30 18:00 +0100
      Re: WARNING: CPU: 12 PID: 16862 at  ./arch/x86/include/asm/thread_info.h:236 Oleg Nesterov <oleg@redhat.com> - 2015-11-30 19:50 +0100

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