Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752106Ab3ITPRf (ORCPT ); Fri, 20 Sep 2013 11:17:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47826 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652Ab3ITPRd (ORCPT ); Fri, 20 Sep 2013 11:17:33 -0400 Date: Fri, 20 Sep 2013 17:19:16 +0200 From: Alexander Gordeev To: "Nicholas A. Bellinger" , Jens Axboe Cc: Mike Christie , James Bottomley , Jens Axboe , Tejun Heo , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, Jeff Garzik , linux-scsi Subject: Re: [PATCH RESEND 0/1] AHCI: Optimize interrupt processing Message-ID: <20130920151915.GC10507@dhcp-26-207.brq.redhat.com> References: <1374195825.7397.997.camel@haakon3.risingtidesystems.com> <1374215660.7397.1041.camel@haakon3.risingtidesystems.com> <1374248000.2266.20.camel@dabdike> <1374267684.7397.1058.camel@haakon3.risingtidesystems.com> <1374296162.7397.1098.camel@haakon3.risingtidesystems.com> <51EAA33C.9010405@fusionio.com> <20130809191542.GD25306@dhcp-26-207.brq.redhat.com> <1376079457.5171.172.camel@haakon3.risingtidesystems.com> <20130815162316.GA27882@dhcp-26-207.brq.redhat.com> <1376619569.5171.217.camel@haakon3.risingtidesystems.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1376619569.5171.217.camel@haakon3.risingtidesystems.com> 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: 2338 Lines: 67 On Thu, Aug 15, 2013 at 07:19:29PM -0700, Nicholas A. Bellinger wrote: > Ok, here's a bit better idea of what is going on now.. > > The problem is that blkdev_issue_flush() -> blk_mq_make_request() -> > __blk_mq_alloc_request() allocates the first tag, which calls > blk_insert_flush() -> blk_flush_complete_seq() -> blk_flush_kick() -> > mq_flush_work() -> blk_mq_alloc_request() to allocate a second tag for > the struct request that actually gets dispatched into scsi-mq as a > SYCHRONIZE_CACHE command.. > > I'm not exactly sure why this double tag usage of struct request is > occurring, but AFAICT it does happen for every flush, and is not > specific to the blkdev_issue_flush() codepath.. I'm sure that Jens can > fill us in on that bit. ;) I also played with the double tag using a reserved tag (below). While it fixes 'fdisk /dev/sda' issue when trying to 'mount /dev/sda1 /mnt' what appears to be a call to bio->bi_end_io() from the free'd bio hits in. Not sure if I should pursue the root cause until the whole double-tag thingy is confirmed. Jens? diff --git a/block/blk-mq.c b/block/blk-mq.c index 6fc1df3..81794dc 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -874,14 +874,14 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio) hctx = q->mq_ops->map_queue(q, ctx->cpu); trace_block_getrq(q, bio, rw); - rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false); + rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, is_flush_fua); if (likely(rq)) blk_mq_rq_ctx_init(ctx, rq, rw); else { blk_mq_put_ctx(ctx); trace_block_sleeprq(q, bio, rw); rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC, - false); + is_flush_fua); ctx = rq->mq_ctx; hctx = q->mq_ops->map_queue(q, ctx->cpu); } @@ -1317,6 +1317,9 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg, reg->queue_depth = BLK_MQ_MAX_DEPTH; } + reg->queue_depth++; + reg->reserved_tags++; + ctx = alloc_percpu(struct blk_mq_ctx); if (!ctx) return ERR_PTR(-ENOMEM); -- Regards, Alexander Gordeev agordeev@redhat.com -- 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/