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Subject: Re: pipe_release oops.
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Jones <davej@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>
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On Thu, Mar 7, 2013 at 2:36 PM, Dave Jones <davej@redhat.com> wrote:
>
> The hits keep on coming..
>
> [  255.609172] BUG: unable to handle kernel NULL pointer dereference at 0000000000000064
> [  255.610393] IP: [<ffffffff811bad62>] pipe_release+0x42/0xd0

Ok, I think this is the same issue as your fasync thing.

So add a "if (pipe) { }" in pipe_release() too.

It's a bit odd, becuse we always allocate an inode->i_pipe whenever we
associate the file with any of the pipe operations, so I don't see how
that NULL i_pipe happens. But we do have that "free_pipe_info() if
there are no readers or writers" logic and I bet that's what triggers
this somehow. I just don't see what the exact sequence is.

                    Linus
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