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=-7.5 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 autolearn=no 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 C9FCDC2D0A8 for ; Mon, 28 Sep 2020 17:31:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 86398208D5 for ; Mon, 28 Sep 2020 17:31:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601314297; bh=kGE2Xqe72I6KcltUsTs8gsQOC9SqlAdV0zI8wy7KvV8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=pMuZHt7sBaDZV1q0i7wy+fxwtIlHxeEqJIvmDjQ19A/4gpd2nYJqpofVtUrxR4+28 sN7oCZLhEttuTNkIpJlr3CZZxCoXL4PVZL9V1T/FcAoukLZdEYWcDV8CmvcxVljg3q SOmL/mJZaQhU5kyQ639Fqnz+uwtM7u9bXGuilhzM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726558AbgI1Rbh (ORCPT ); Mon, 28 Sep 2020 13:31:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:45560 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbgI1Rbh (ORCPT ); Mon, 28 Sep 2020 13:31:37 -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 3D36D2083B; Mon, 28 Sep 2020 17:31:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601314296; bh=kGE2Xqe72I6KcltUsTs8gsQOC9SqlAdV0zI8wy7KvV8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BW97N4in7WTP2H5OPsNBCaqZfKiGptfpCQs6svDwSleZxHBNe6IjKumQJntldpN3c 8efTgE7BcghC8stC6egt+syx221HrsrXTpyeM6GHZ7lFkJYTZhyx5liCm8zy3RQXlK hOZrsBNyt2wTT7QIDJKjOQvutxs0ESHWh+R24ics= Date: Mon, 28 Sep 2020 19:31:44 +0200 From: Greg KH To: Mike Snitzer Cc: ming.lei@redhat.com, stable@vger.kernel.org Subject: Re: [PATCH 5.4, 5.8] dm: fix bio splitting and its bio completion order for regular IO Message-ID: <20200928173144.GA2042505@kroah.com> References: <1601301410240130@kroah.com> <20200928152941.GA66303@lobo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928152941.GA66303@lobo> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Sep 28, 2020 at 11:29:41AM -0400, Mike Snitzer wrote: > This backport applies (with mild offset) to both v5.4.67 and v5.8.11: > > >From ee1dfad5325ff1cfb2239e564cd411b3bfe8667a Mon Sep 17 00:00:00 2001 > From: Mike Snitzer > Date: Mon, 14 Sep 2020 13:04:19 -0400 > Subject: [PATCH] dm: fix bio splitting and its bio completion order for regular IO > > 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 What is the git id of this patch in Linus's tree? thanks, greg k-h