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Date: Fri, 1 Oct 2004 12:09:26 -0700
From: Andrew Morton <akpm@osdl.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.6.9-rc2-mm4 ps hang ?
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Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
> I randomly see "ps" hangs on my AMD64 system running 2.6.9-rc2-mm4.
>  I don't remember seeing this on earlier kernels. Is this something
>  known/fixed ?

hm.  I can see that access_process_vm() is doing lock_page() inside
mmap_sem, which is a ranking bug, but it's not that.

And I see a distinct lack of flush_foo_page() calls after the by-hand
modification of the user page.  But it's not that either.

Can you work out who is holding mmap_sem for writing?