Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753989AbcDFA7g (ORCPT ); Tue, 5 Apr 2016 20:59:36 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49028 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750959AbcDFA7f (ORCPT ); Tue, 5 Apr 2016 20:59:35 -0400 MIME-Version: 1.0 In-Reply-To: <20160406003025.GC31161@kmo-pixel> References: <1459878246-9249-1-git-send-email-ming.lei@canonical.com> <20160406003025.GC31161@kmo-pixel> Date: Wed, 6 Apr 2016 08:59:31 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] block: make sure big bio is splitted into at most 256 bvecs From: Ming Lei To: Kent Overstreet Cc: Jens Axboe , Linux Kernel Mailing List , linux-block@vger.kernel.org, Christoph Hellwig , Eric Wheeler , Sebastian Roesner , "4.2+" , Shaohua Li Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1206 Lines: 34 On Wed, Apr 6, 2016 at 8:30 AM, Kent Overstreet wrote: > On Wed, Apr 06, 2016 at 01:44:06AM +0800, Ming Lei wrote: >> After arbitrary bio size is supported, the incoming bio may >> be very big. We have to split the bio into small bios so that >> each holds at most BIO_MAX_PAGES bvecs for safety reason, such >> as bio_clone(). >> >> This patch fixes the following kernel crash: > > Ming, let's not do it this way; drivers that don't clone biovecs are the norm - > instead, md has its own queue limits that it ought to be setting up correctly. Except for md, there are also several usages of bio_clone: - drbd - osdblk - pktcdvd - xen-blkfront - verify code of bcache I don't like bio_clone() too, which can cause trouble to multipage bvecs. How about fixing the issue by this simple patch first? Then once we limits all above queues by max sectors, the global limit can be removed as mentioned by the comment. thanks, Ming > -- > To unsubscribe from this list: send the line "unsubscribe linux-block" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html