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=-10.5 required=3.0 tests=BAYES_00,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 EBB34C4727C for ; Tue, 29 Sep 2020 11:49:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6973206E5 for ; Tue, 29 Sep 2020 11:49:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601380192; bh=ZMsci1YJfYVsPbkyDybU7bYlS3bhV7BP1CqT/yZEbeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=BBdlOEQllbUEgHG4mQAuTluixosOvxadEe7PO7IWDeaEBFaGTel5F/1K/o2K1eSPQ 4QMhSz4st+7HRf/iK9CFFDLGOUWDO3dtuwIPSRph+h9/myoaSYccDQM//1HdJdr7FH +88PzLTV1P02o5ryj4NleLLvqfr8urEqqPNDICe8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731255AbgI2Ltu (ORCPT ); Tue, 29 Sep 2020 07:49:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:52870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730346AbgI2Lt3 (ORCPT ); Tue, 29 Sep 2020 07:49:29 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 ED1D22075F; Tue, 29 Sep 2020 11:49:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601380168; bh=ZMsci1YJfYVsPbkyDybU7bYlS3bhV7BP1CqT/yZEbeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OJb2bUj0PL6p2Ju9zxVEWuauYiJT3/PZDZLqd8exs0+z+aR8qV+ocrwWjbP+/Eze1 2w8mPtoQzZXM+tVGVT9d4dDLcfiIanS7EA+ZmLxe2zALoFF/VBU5U5jnu0ktMEnkHf B/4DJXgV/3jYagF0OPDSe9EWZi3rq6VJUdaacHLU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ming Lei , Mike Snitzer Subject: [PATCH 5.8 98/99] dm: fix bio splitting and its bio completion order for regular IO Date: Tue, 29 Sep 2020 13:02:21 +0200 Message-Id: <20200929105934.566270042@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929105929.719230296@linuxfoundation.org> References: <20200929105929.719230296@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mike Snitzer commit ee1dfad5325ff1cfb2239e564cd411b3bfe8667a upstream. dm_queue_split() is removed because __split_and_process_bio() _must_ handle splitting bios to ensure proper bio submission and completion ordering as a bio is split. Otherwise, multiple recursive calls to ->submit_bio will cause multiple split bios to be allocated from the same ->bio_split mempool at the same time. This would result in deadlock in low memory conditions because no progress could be made (only one bio is available in ->bio_split mempool). This fix has been verified to still fix the loss of performance, due to excess splitting, that commit 120c9257f5f1 provided. Fixes: 120c9257f5f1 ("Revert "dm: always call blk_queue_split() in dm_process_bio()"") Cc: stable@vger.kernel.org # 5.0+, requires custom backport due to 5.9 changes Reported-by: Ming Lei Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 23 ++--------------------- 1 file changed, 2 insertions(+), 21 deletions(-) --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1728,23 +1728,6 @@ out: return ret; } -static void dm_queue_split(struct mapped_device *md, struct dm_target *ti, struct bio **bio) -{ - unsigned len, sector_count; - - sector_count = bio_sectors(*bio); - len = min_t(sector_t, max_io_len((*bio)->bi_iter.bi_sector, ti), sector_count); - - if (sector_count > len) { - struct bio *split = bio_split(*bio, len, GFP_NOIO, &md->queue->bio_split); - - bio_chain(split, *bio); - trace_block_split(md->queue, split, (*bio)->bi_iter.bi_sector); - generic_make_request(*bio); - *bio = split; - } -} - static blk_qc_t dm_process_bio(struct mapped_device *md, struct dm_table *map, struct bio *bio) { @@ -1772,14 +1755,12 @@ static blk_qc_t dm_process_bio(struct ma if (current->bio_list) { if (is_abnormal_io(bio)) blk_queue_split(md->queue, &bio); - else - dm_queue_split(md, ti, &bio); + /* regular IO is split by __split_and_process_bio */ } if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED) return __process_bio(md, map, bio, ti); - else - return __split_and_process_bio(md, map, bio); + return __split_and_process_bio(md, map, bio); } static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)