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Date: Wed, 26 May 2010 00:13:49 +0200
From: Albert Herranz <albert_herranz@yahoo.es>
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To: Nick Piggin <npiggin@suse.de>
CC: aya Kumar <jayakumar.lkml@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>, linux-mm@kvack.org,
       linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
       linux-fbdev@vger.kernel.org
Subject: Re: [Bulk] Re: page_mkwrite vs pte dirty race in fb_defio
References: <20100525160149.GE20853@laptop> <4BFC1657.5000707@yahoo.es> <20100525184700.GJ20853@laptop>
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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