From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v2 22/26] block: Add bio_alloc_pages() Date: Thu, 20 Sep 2012 17:47:11 -0700 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 Return-path: Content-Disposition: inline In-Reply-To: <1347322957-25260-23-git-send-email-koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Kent Overstreet Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, neilb-l3A5Bk7waGM@public.gmane.org List-Id: linux-bcache@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