From mboxrd@z Thu Jan 1 00:00:00 1970 From: Minchan Kim Subject: Re: [patch 3/9] mm: shmem: save one radix tree lookup when truncating swapped pages Date: Mon, 25 Nov 2013 17:21:52 +0900 Message-ID: <20131125082152.GC4731@bbox> References: <1385336308-27121-1-git-send-email-hannes@cmpxchg.org> <1385336308-27121-4-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Dave Chinner , Rik van Riel , Jan Kara , Vlastimil Babka , Peter Zijlstra , Tejun Heo , Andi Kleen , Andrea Arcangeli , Greg Thelen , Christoph Hellwig , Hugh Dickins , KOSAKI Motohiro , Mel Gorman , Michel Lespinasse , Seth Jennings , Roman Gushchin , Ozgun Erdogan , Metin Doslu , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Johannes Weiner Return-path: Content-Disposition: inline In-Reply-To: <1385336308-27121-4-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Sun, Nov 24, 2013 at 06:38:22PM -0500, Johannes Weiner wrote: > Page cache radix tree slots are usually stabilized by the page lock, > but shmem's swap cookies have no such thing. Because the overall > truncation loop is lockless, the swap entry is currently confirmed by > a tree lookup and then deleted by another tree lookup under the same > tree lock region. > > Use radix_tree_delete_item() instead, which does the verification and > deletion with only one lookup. This also allows removing the > delete-only special case from shmem_radix_tree_replace(). > > Signed-off-by: Johannes Weiner Reviewed-by: Minchan Kim Nice cleanup! -- Kind regards, Minchan Kim -- 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