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

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Date:	Thu, 19 Mar 2009 14:17:57 -0700
From:	Ying Han <yinghan@...gle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Nick Piggin <nickpiggin@...oo.com.au>, 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 Thu, Mar 19, 2009 at 1:21 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
>
> On Thu, 19 Mar 2009, Linus Torvalds wrote:
>>
>> 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 ;)
>
> Oh, btw, can people who see this (Ying Han, Nick and apparently Jan)
> detail their configurations, please? In particular
>
>  - SMP? (CONFIG_SMP and how many cores do you have if so?)
"CONFIG_SMP=y"
the testing machine i was using has 16 cores.

>
>  - PREEMPT (NONE/VOLUNTARY or full preempt?)
CONFIG_PREEMPT_NONE=y
# CONFIG_PREEMPT_VOLUNTARY is not set
# CONFIG_PREEMPT is not set
CONFIG_PREEMPT_BKL=y

>
>  - RCU (CLASSIC/TREE/PREEMPT?)
Not in my .config file.
>
> since those affect the kinds of races we can see a lot.
>
>                        Linus
>
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