From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: page_mkwrite vs pte dirty race in fb_defio Date: Wed, 26 May 2010 02:01:49 +1000 Message-ID: <20100525160149.GE20853@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Albert Herranz , aya Kumar , Andrew Morton , Linus Torvalds , linux-mm@kvack.org Return-path: Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org Hi, I couldn't find where this patch (49bbd815fd8) was discussed, so I'll make my own thread. Adding a few lists to cc because it might be of interest to driver and filesystem writers. The old ->page_mkwrite calling convention was causing problems exactly because of this race, and we solved it by allowing page_mkwrite to return with the page locked, and the lock will be held until the pte is marked dirty. See commit b827e496c893de0c0f142abfaeb8730a2fd6b37f. 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). Thanks, Nick -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org