linux-kernel - Re: WARNING: CPU: 12 PID: 16862 at ./arch/x86/include/asm/thread

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Date:	Mon, 30 Nov 2015 19:48:04 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Sasha Levin <sasha.levin@...cle.com>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: WARNING: CPU: 12 PID: 16862 at
	./arch/x86/include/asm/thread_info.h:236

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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