From: Simon Jeons <simon.jeons@gmail.com>
To: Michel Lespinasse <walken@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Hugh Dickins <hughd@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: protect against concurrent vma expansion
Date: Thu, 03 Jan 2013 18:40:05 -0600 [thread overview]
Message-ID: <1357260005.4930.6.camel@kernel.cn.ibm.com> (raw)
In-Reply-To: <CANN689FoSGMUi0mC6dzXe5tXo-BL_4eFZ1NF-De38x8mNhPXcg@mail.gmail.com>
On Wed, 2012-12-19 at 19:01 -0800, Michel Lespinasse wrote:
> Hi Simon,
>
> On Wed, Dec 19, 2012 at 5:56 PM, Simon Jeons <simon.jeons@gmail.com> wrote:
> > One question.
> >
> > I found that mainly callsite of expand_stack() is #PF, but it holds
> > mmap_sem each time before call expand_stack(), how can hold a *shared*
> > mmap_sem happen?
>
> the #PF handler calls down_read(&mm->mmap_sem) before calling expand_stack.
>
> I think I'm just confusing you with my terminology; shared lock ==
> read lock == several readers might hold it at once (I'd say they share
> it)
Sorry for my late response.
Since expand_stack() will modify vma, then why hold a read lock here?
>
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next prev parent reply other threads:[~2013-01-04 0:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-01 6:56 [PATCH] mm: protect against concurrent vma expansion Michel Lespinasse
2012-12-03 23:01 ` Andrew Morton
2012-12-04 0:35 ` Michel Lespinasse
2012-12-04 0:43 ` Andrew Morton
2012-12-04 14:48 ` Michel Lespinasse
2012-12-20 1:56 ` Simon Jeons
2012-12-20 3:01 ` Michel Lespinasse
2013-01-04 0:40 ` Simon Jeons [this message]
2013-01-04 0:50 ` Michel Lespinasse
2013-01-04 1:18 ` Simon Jeons
2013-01-04 2:49 ` Al Viro
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