From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756777Ab2IUArR (ORCPT ); Thu, 20 Sep 2012 20:47:17 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:58329 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756672Ab2IUArP (ORCPT ); Thu, 20 Sep 2012 20:47:15 -0400 Date: Thu, 20 Sep 2012 17:47:11 -0700 From: Tejun Heo To: Kent Overstreet Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, axboe@kernel.dk, neilb@suse.de Subject: Re: [PATCH v2 22/26] block: Add bio_alloc_pages() Message-ID: <20120921004711.GZ7264@google.com> References: <1347322957-25260-1-git-send-email-koverstreet@google.com> <1347322957-25260-23-git-send-email-koverstreet@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1347322957-25260-23-git-send-email-koverstreet@google.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 10, 2012 at 05:22:33PM -0700, Kent Overstreet wrote: > + bio_for_each_segment_all(bv, bio, i) { > + bv->bv_page = alloc_page(gfp_mask); > + if (!bv->bv_page) { > + while (bv-- != bio->bi_io_vec) > + __free_page(bv->bv_page); I don't know. I feel stupid. I think it's because the loop variable changes between loop condition test and actual body of loop. How about the following? It is pointing to the member of the same array so I think it's not even violating pointer comparison rules. while (--bv >= bio->bi_io_vec) __free_page(bv->bv_page); -- tejun