From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 482ECC433F5 for ; Wed, 23 Feb 2022 12:34:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239282AbiBWMfF (ORCPT ); Wed, 23 Feb 2022 07:35:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232550AbiBWMfE (ORCPT ); Wed, 23 Feb 2022 07:35:04 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FB528AE46 for ; Wed, 23 Feb 2022 04:34:36 -0800 (PST) Received: from canpemm500005.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4K3b696cgkz9svL; Wed, 23 Feb 2022 20:32:49 +0800 (CST) Received: from [10.174.178.134] (10.174.178.134) by canpemm500005.china.huawei.com (7.192.104.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 23 Feb 2022 20:34:33 +0800 Subject: Re: dm: make sure dm_table is binded before queue request To: Mike Snitzer CC: , , , , References: <20220209093751.2986716-1-yi.zhang@huawei.com> From: Zhang Yi Message-ID: Date: Wed, 23 Feb 2022 20:34:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.134] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500005.china.huawei.com (7.192.104.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2022/2/23 2:27, Mike Snitzer wrote: > On Wed, Feb 09 2022 at 4:37P -0500, > Zhang Yi wrote: > >> We found a NULL pointer dereference problem when using dm-mpath target. >> The problem is if we submit IO between loading and binding the table, >> we could neither get a valid dm_target nor a valid dm table when >> submitting request in dm_mq_queue_rq(). BIO based dm target could >> handle this case in dm_submit_bio(). This patch fix this by checking >> the mapping table before submitting request. >> >> Signed-off-by: Zhang Yi >> --- >> drivers/md/dm-rq.c | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c >> index 579ab6183d4d..af2cf71519e9 100644 >> --- a/drivers/md/dm-rq.c >> +++ b/drivers/md/dm-rq.c >> @@ -499,8 +499,15 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, >> >> if (unlikely(!ti)) { >> int srcu_idx; >> - struct dm_table *map = dm_get_live_table(md, &srcu_idx); >> - >> + struct dm_table *map; >> + >> + map = dm_get_live_table(md, &srcu_idx); >> + if (!map) { >> + DMERR_LIMIT("%s: mapping table unavailable, erroring io", >> + dm_device_name(md)); >> + dm_put_live_table(md, srcu_idx); >> + return BLK_STS_IOERR; >> + } >> ti = dm_table_find_target(map, 0); >> dm_put_live_table(md, srcu_idx); >> } >> -- >> 2.31.1 >> > > I think both dm_submit_bio() and now dm_mq_queue_rq() should _not_ > error the IO. This is such a narrow race during device setup that it > best to requeue the IO. > Yes，make sense, thanks for the fix. Thanks, Yi. > I'll queue this for 5.18: > > diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c > index 6948d5db9092..3dd040a56318 100644 > --- a/drivers/md/dm-rq.c > +++ b/drivers/md/dm-rq.c > @@ -491,8 +491,13 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx, > > if (unlikely(!ti)) { > int srcu_idx; > - struct dm_table *map = dm_get_live_table(md, &srcu_idx); > + struct dm_table *map; > > + map = dm_get_live_table(md, &srcu_idx); > + if (unlikely(!map)) { > + dm_put_live_table(md, srcu_idx); > + return BLK_STS_RESOURCE; > + } > ti = dm_table_find_target(map, 0); > dm_put_live_table(md, srcu_idx); > } > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index 082366d0ad49..c70be6e5ed55 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1533,15 +1533,10 @@ static void dm_submit_bio(struct bio *bio) > struct dm_table *map; > > map = dm_get_live_table(md, &srcu_idx); > - if (unlikely(!map)) { > - DMERR_LIMIT("%s: mapping table unavailable, erroring io", > - dm_device_name(md)); > - bio_io_error(bio); > - goto out; > - } > > - /* If suspended, queue this IO for later */ > - if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) { > + /* If suspended, or map not yet available, queue this IO for later */ > + if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) || > + unlikely(!map)) { > if (bio->bi_opf & REQ_NOWAIT) > bio_wouldblock_error(bio); > else if (bio->bi_opf & REQ_RAHEAD) > > . > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 268B0C433EF for ; Mon, 28 Feb 2022 06:25:28 +0000 (UTC) Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-358-44FwEoJBMpqmvJpGhRvzWQ-1; 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Wed, 23 Feb 2022 20:34:33 +0800 To: Mike Snitzer References: <20220209093751.2986716-1-yi.zhang@huawei.com> From: Zhang Yi Message-ID: Date: Wed, 23 Feb 2022 20:34:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [10.174.178.134] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500005.china.huawei.com (7.192.104.229) X-CFilter-Loop: Reflected X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 21NCYhKM021583 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Mon, 28 Feb 2022 01:25:13 -0500 Cc: linux-block@vger.kernel.org, axboe@kernel.dk, dm-devel@redhat.com, agk@redhat.com, yukuai3@huawei.com Subject: Re: [dm-devel] dm: make sure dm_table is binded before queue request X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; 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