linux-kernel - Re: [PATCH v2] mm: Downgrade mmap_sem before locking or populating on mmap

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Message-ID: <20121217095231.GA1134@gmail.com>
Date:	Mon, 17 Dec 2012 10:52:31 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Michel Lespinasse <walken@...gle.com>,
	Hugh Dickins <hughd@...gle.com>, J??rn Engel <joern@...fs.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2] mm: Downgrade mmap_sem before locking or populating
 on mmap


* Andy Lutomirski <luto@...capital.net> wrote:

> > 2)
> >
> > More aggressively, we could just make it the _rule_ that the 
> > mm lock gets downgraded to read in mmap_region_helper(), no 
> > matter what.
> >
> > From a quick look I *think* all the usage sites (including 
> > sys_aio_setup()) are fine with that unlocking - but I could 
> > be wrong.
> 
> They are.

Lets try that then - the ugliness of the current patch is 
certainly a problem.

Thanks,

	Ingo
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