Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752988Ab2HOWTm (ORCPT ); Wed, 15 Aug 2012 18:19:42 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:49779 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751388Ab2HOWTk (ORCPT ); Wed, 15 Aug 2012 18:19:40 -0400 Date: Wed, 15 Aug 2012 15:19:36 -0700 From: Kent Overstreet To: Tejun Heo Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dm-devel@redhat.com, axboe@kernel.dk, agk@redhat.com, neilb@suse.de, drbd-dev@lists.linbit.com, vgoyal@redhat.com, mpatocka@redhat.com, sage@newdream.net, yehuda@hq.newdream.net Subject: Re: [PATCH v5 05/12] block: Kill bi_destructor Message-ID: <20120815221936.GC2758@google.com> References: <1344290921-25154-1-git-send-email-koverstreet@google.com> <1344290921-25154-6-git-send-email-koverstreet@google.com> <20120808222223.GD6983@dhcp-172-17-108-109.mtv.corp.google.com> <20120809002154.GE7262@moria.home.lan> <20120809060517.GB2845@dhcp-172-17-108-109.mtv.corp.google.com> <20120809061214.GA9128@dhcp-172-18-216-138.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1486 Lines: 34 On Wed, Aug 08, 2012 at 11:34:09PM -0700, Tejun Heo wrote: > Hello, > > On Wed, Aug 8, 2012 at 11:12 PM, Kent Overstreet wrote: > > But if it's a pointer to heap allocated memory, but the bio was embedded > > in another struct? I've seen a fair number of instances of that (md, off > > the top of my head). > > > > If you're sure that in a normal config the slab allocator is going to > > complain right away and not corrupt itself, fine. But I've been bitten > > way too hard by bugs that could've been caught right away by a simple > > assert and instead I had to spend hours backtracking, and the block > > layer is _rife_ with that kind of thing. > > Let's let slab debug code deal with that. I really don't see much > benefit in doing this. The said kind of bugs aren't particularly > difficult to track down. The only difference would be changing #define BIO_KMALLOC_POOL ((void *) ~0) to #define BIO_KMALLOC_POOL NULL We want a define for this - bio_alloc_bioset(GFP_KERNEL, 1, NULL) doesn't make any sense. I just don't see the argument for changing an arbitrary constant... If it's just the ~0 pointer you don't like, I originally used a real statically allocated struct bio_set as a sentinel value. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/