linux-kernel - Re: ftruncate-mmap: pages are lost after writing to mmaped file.

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Date:	Thu, 19 Mar 2009 09:51:59 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Nick Piggin <nickpiggin@...oo.com.au>
cc:	Ying Han <yinghan@...gle.com>, Jan Kara <jack@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, guichaz@...il.com,
	Alex Khesin <alexk@...gle.com>,
	Mike Waychison <mikew@...gle.com>,
	Rohit Seth <rohitseth@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: ftruncate-mmap: pages are lost after writing to mmaped file.



On Fri, 20 Mar 2009, Nick Piggin wrote:
> 
> Yeah, probably no need to hold private_lock while tagging the radix
> tree (which is what my version did). So maybe this one is a little
> better. I did test mine, it worked, but it didn't solve the problem.

Ahh, so you re-created it? On ext2 only, or is it visible on ext3 as well? 
I've not even tested - I assumed that I would have to boot into less 
memory and downgrade my filesystem to ext2, which made me hope somebody 
else would pick it up first ;)

> Still, it does appear to solve a real race, which we should close.

A very small and unlikely race, but yeah - the patch isn't large, removes 
more lines than it adds, and the code seems to make _more_ sense with it 
in place than without. 

			Linus
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