From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755723AbZCEKJU (ORCPT ); Thu, 5 Mar 2009 05:09:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753074AbZCEKJF (ORCPT ); Thu, 5 Mar 2009 05:09:05 -0500 Received: from brick.kernel.dk ([93.163.65.50]:39466 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbZCEKJD (ORCPT ); Thu, 5 Mar 2009 05:09:03 -0500 Date: Thu, 5 Mar 2009 11:09:01 +0100 From: Jens Axboe To: FUJITA Tomonori Cc: tglx@linutronix.de, James.Bottomley@HansenPartnership.com, jengelh@medozas.de, bharrosh@panasas.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Subject: Re: [BUG] 2.6.29-rc6-2450cf in scsi_lib.c (was: Large amount of scsi-sgpool)objects Message-ID: <20090305100901.GU11787@kernel.dk> References: <1236207389.21486.19.camel@localhost.localdomain> <20090305173649M.fujita.tomonori@lab.ntt.co.jp> <20090305173952U.fujita.tomonori@lab.ntt.co.jp> <20090305182958Q.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090305182958Q.fujita.tomonori@lab.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 05 2009, FUJITA Tomonori wrote: > Oops, somehow I forgot to CC Jens... > > On Thu, 5 Mar 2009 17:39:17 +0900 > FUJITA Tomonori wrote: > > > On Thu, 5 Mar 2009 17:36:13 +0900 > > FUJITA Tomonori wrote: > > > > > CC'ed Jens, > > > > > > On Wed, 04 Mar 2009 22:56:29 +0000 > > > James Bottomley wrote: > > > > > > > On Wed, 2009-03-04 at 22:45 +0100, Thomas Gleixner wrote: > > > > > On Wed, 4 Mar 2009, Thomas Gleixner wrote: > > > > > > > > > > Instrumented the code and the result of the failing request is > > > > > below. Looks like the function which sets up the request gets > > > > > nr_phys_segments wrong by one. > > > > > > > > > > If you need further trace data feel free to ask. > > > > > > > > OK, the mapping all checks out correctly ... there must be something > > > > wrong with the way we count before mapping. > > > > > > Yeah, looks we miscalculate nr_phys_segments in the merging path. > > > > > > blk_recount_segments() needs to set bi_seg_front_size and > > > bi_seg_back_size for ll_merge_requests_fn()? > > > > > > = > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > > index a104593..efb65b6 100644 > > > --- a/block/blk-merge.c > > > +++ b/block/blk-merge.c > > > @@ -111,12 +111,19 @@ void blk_recalc_rq_segments(struct request *rq) > > > > > > void blk_recount_segments(struct request_queue *q, struct bio *bio) > > > { > > > + unsigned int seg_size; > > > struct bio *nxt = bio->bi_next; > > > > > > bio->bi_next = NULL; > > > - bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL); > > > + bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, &seg_size); > > > bio->bi_next = nxt; > > > bio->bi_flags |= (1 << BIO_SEG_VALID); > > > + > > > + if (bio->bi_phys_segments == 1 && seg_size > bio->bi_seg_front_size) > > > + bio->bi_seg_front_size = seg_size; > > > + if (bio->bi_phys_segments > bio->bi_seg_back_size) > > > + bio->bi_seg_back_size = seg_size; > > > + > > > } > > > EXPORT_SYMBOL(blk_recount_segments); > > > > Duh, here's the proper patch. > > > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index a104593..06e0db4 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -111,12 +111,19 @@ void blk_recalc_rq_segments(struct request *rq) > > > > void blk_recount_segments(struct request_queue *q, struct bio *bio) > > { > > + unsigned int seg_size; > > struct bio *nxt = bio->bi_next; > > > > bio->bi_next = NULL; > > - bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL); > > + bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, &seg_size); > > bio->bi_next = nxt; > > bio->bi_flags |= (1 << BIO_SEG_VALID); > > + > > + if (bio->bi_phys_segments == 1 && seg_size > bio->bi_seg_front_size) > > + bio->bi_seg_front_size = seg_size; > > + if (seg_size > bio->bi_seg_back_size) > > + bio->bi_seg_back_size = seg_size; > > + > > } > > EXPORT_SYMBOL(blk_recount_segments); Good catch, I merged it with a slight change of layout and clearing seg_size initially, to avoid gcc silly errors. -- Jens Axboe