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Date: Thu, 25 Feb 2016 03:18:52 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org
Subject: Re: [PATCH] signals: work around random wakeups in sigsuspend()
Message-ID: <20160225031852.GV17997@ZenIV.linux.org.uk>
References: <1453735306-13519-1-git-send-email-sasha.levin@oracle.com>
 <20160125190915.GA9362@redhat.com>
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On Mon, Jan 25, 2016 at 08:09:15PM +0100, Oleg Nesterov wrote:
> On 01/25, Sasha Levin wrote:
> >
> > A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
> > being set.
> 
> and TIF_RESTORE_SIGMASK is just wrong in this case. I'd say this is the
> bugfix, not work-around ;)
> 
> > Avoid that by making sure we were signaled, like sys_pause() does.
> >
> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> 
> Acked-by: Oleg Nesterov <oleg@redhat.com>
> 
> Thanks Sasha.

Out of curiousity - where did that stray wakeup come from?  PTRACE_KILL
used to trigger those, but that got fixed.  How does one trigger that
kind of bugs on the current kernels?