linux-kernel - Re: [RFC] page fault retry with NOPAGE

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Message-ID: <Pine.LNX.4.64.0609151425050.22674@blonde.wat.veritas.com>
Date:	Fri, 15 Sep 2006 14:30:24 +0100 (BST)
From:	Hugh Dickins <hugh@...itas.com>
To:	Andrew Morton <akpm@...l.org>
cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linux-mm@...ck.org,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...l.org>,
	Mike Waychison <mikew@...gle.com>
Subject: Re: [RFC] page fault retry with NOPAGE_RETRY

On Fri, 15 Sep 2006, Andrew Morton wrote:
> 
> This assumes that no other heavyweight process will try to modify this
> single-threaded process's mm.  I don't _think_ that happens anywhere, does
> it?  access_process_vm() is the only case I can think of,

"Modify" in the sense of fault into.
Yes, access_process_vm() is all I can think of too.

> and it does down_read(other process's mmap_sem).

If there were anything else, it'd have to do so too (if not down_write).

I too like NOPAGE_RETRY: as you've both observed, it can help to solve
several different problems.

Hugh
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