linux-kernel - Re: [Bulk] Re: page_mkwrite vs pte dirty race in fb

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Date:	Wed, 26 May 2010 00:13:49 +0200
From:	Albert Herranz <albert_herranz@...oo.es>
To:	Nick Piggin <npiggin@...e.de>
CC:	aya Kumar <jayakumar.lkml@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [Bulk] Re: page_mkwrite vs pte dirty race in fb_defio

On 05/25/2010 08:47 PM, Nick Piggin wrote:
>>> I hope that should provide a more elegant solution to your problem. I
>>> would really like you to take a look at that, because we already have
>>> filesystem code (NFS) relying on it, and more code we have relying on
>>> this synchronization, the more chance we would find a subtle problem
>>> with it (also it should be just nicer).
>>
>> So if I undestand it correctly, using the "new" calling convention I should just lock the page on fb_deferred_io_mkwrite() and return VM_FAULT_LOCKED to fix the described race for fb_defio.
> 
> As far as I can see from quick reading of the fb_defio code, yes
> that should solve it (provided you lock the page inside the mutex,
> of course).
> 

Ok, thanks. I'm posting a new version as RFT.

Cheers,
Albert

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