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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18E03C10F27 for ; Tue, 10 Mar 2020 13:14:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E521F24649 for ; Tue, 10 Mar 2020 13:14:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583846099; bh=LOH85/x3D4YpyOFgIuC3ZBsEchD+aCjhnBXoY9/o9eM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=x/znneRQPRBKoH/IGHRatU+QQuc15S2lSNysIYuv3CHYVBkUfTQ1i92sCejCaXbSb uP0/sK3pCSpyzD5uPP4dt5cQCjz69gBo3rBbJij32b6iEq9lAyOB1G7PrWhjZhYhRE ULLUIgRyVRVAO/4bAsw97hX086i0YmzCjv/O8V98= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731733AbgCJNO5 (ORCPT ); Tue, 10 Mar 2020 09:14:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:39052 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731938AbgCJNOx (ORCPT ); Tue, 10 Mar 2020 09:14:53 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 823CD2467D; Tue, 10 Mar 2020 13:14:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583846093; bh=LOH85/x3D4YpyOFgIuC3ZBsEchD+aCjhnBXoY9/o9eM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0avQhl6GkJaqRx3muiZdJfzqlT+QeRfhZDsQ6JDeg3FQNSfb+ZQv1ovDMz0BjxUvI E+uOjW7eXnNd9rHSP6MFN8zlUjtUPNluKvhfMnlJY2lXl7a5SIdt5zUjrn6zOzCrNf kmU1FG0Rh/6jE64A+mol6Y2OO7L+ih9iAJKIP+KI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Heinz Mauelshagen , Mikulas Patocka , Mike Snitzer Subject: [PATCH 4.19 85/86] dm integrity: fix a deadlock due to offloading to an incorrect workqueue Date: Tue, 10 Mar 2020 13:45:49 +0100 Message-Id: <20200310124535.461145996@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310124530.808338541@linuxfoundation.org> References: <20200310124530.808338541@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikulas Patocka commit 53770f0ec5fd417429775ba006bc4abe14002335 upstream. If we need to perform synchronous I/O in dm_integrity_map_continue(), we must make sure that we are not in the map function - in order to avoid the deadlock due to bio queuing in generic_make_request. To avoid the deadlock, we offload the request to metadata_wq. However, metadata_wq also processes metadata updates for write requests. If there are too many requests that get offloaded to metadata_wq at the beginning of dm_integrity_map_continue, the workqueue metadata_wq becomes clogged and the system is incapable of processing any metadata updates. This causes a deadlock because all the requests that need to do metadata updates wait for metadata_wq to proceed and metadata_wq waits inside wait_and_add_new_range until some existing request releases its range lock (which doesn't happen because the range lock is released after metadata update). In order to fix the deadlock, we create a new workqueue offload_wq and offload requests to it - so that processing of offload_wq is independent from processing of metadata_wq. Fixes: 7eada909bfd7 ("dm: add integrity target") Cc: stable@vger.kernel.org # v4.12+ Reported-by: Heinz Mauelshagen Tested-by: Heinz Mauelshagen Signed-off-by: Heinz Mauelshagen Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-integrity.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -198,6 +198,7 @@ struct dm_integrity_c { struct list_head wait_list; wait_queue_head_t endio_wait; struct workqueue_struct *wait_wq; + struct workqueue_struct *offload_wq; unsigned char commit_seq; commit_id_t commit_ids[N_COMMIT_IDS]; @@ -1237,7 +1238,7 @@ static void dec_in_flight(struct dm_inte dio->range.logical_sector += dio->range.n_sectors; bio_advance(bio, dio->range.n_sectors << SECTOR_SHIFT); INIT_WORK(&dio->work, integrity_bio_wait); - queue_work(ic->wait_wq, &dio->work); + queue_work(ic->offload_wq, &dio->work); return; } do_endio_flush(ic, dio); @@ -1657,7 +1658,7 @@ static void dm_integrity_map_continue(st if (need_sync_io && from_map) { INIT_WORK(&dio->work, integrity_bio_wait); - queue_work(ic->metadata_wq, &dio->work); + queue_work(ic->offload_wq, &dio->work); return; } @@ -3308,6 +3309,14 @@ static int dm_integrity_ctr(struct dm_ta goto bad; } + ic->offload_wq = alloc_workqueue("dm-integrity-offload", WQ_MEM_RECLAIM, + METADATA_WORKQUEUE_MAX_ACTIVE); + if (!ic->offload_wq) { + ti->error = "Cannot allocate workqueue"; + r = -ENOMEM; + goto bad; + } + ic->commit_wq = alloc_workqueue("dm-integrity-commit", WQ_MEM_RECLAIM, 1); if (!ic->commit_wq) { ti->error = "Cannot allocate workqueue"; @@ -3544,6 +3553,8 @@ static void dm_integrity_dtr(struct dm_t destroy_workqueue(ic->metadata_wq); if (ic->wait_wq) destroy_workqueue(ic->wait_wq); + if (ic->offload_wq) + destroy_workqueue(ic->offload_wq); if (ic->commit_wq) destroy_workqueue(ic->commit_wq); if (ic->writer_wq)