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 1E797C2D0A8 for ; Mon, 28 Sep 2020 17:52:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6D722100A for ; Mon, 28 Sep 2020 17:52:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601315542; bh=cIOZZz5pGoTTPH9X6fMSKHFx29hQmnh0fcEau8zZcUg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=E1gdMY2iGzr5Kzp/wqg3D4kZ7ky8GX42OMwnvzFJB517mBtwnBpH8Al3oM8kN9k3Q 496+X5CkSVMVAtn4Q0A4VfESUcdMy32y54BBFAU6K80RtIpyMav25msLk5DCEQ+9I0 MItqRPdYeRYq+uc6134H3T34vnrqOx/zWDa/jKvM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726547AbgI1RwW (ORCPT ); Mon, 28 Sep 2020 13:52:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:56074 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726442AbgI1RwW (ORCPT ); Mon, 28 Sep 2020 13:52:22 -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 6372C20739; Mon, 28 Sep 2020 17:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601315541; bh=cIOZZz5pGoTTPH9X6fMSKHFx29hQmnh0fcEau8zZcUg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MBACj381Q32kwnugFjtfYEvCjl66iKvWKbEHJg9GQXFqStXRzR/u8pS2Fm/9TgzNo P3p3i11+UzChdSSK4aOeP/Fp/xDOC/JveaJPw/6X2jH+QkwwsITQECjjJv7WBlEoFg se216lUEC4EQ0TdA6ioa7DaBIrv+06S+c/iAUFQM= Date: Mon, 28 Sep 2020 19:52:29 +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: <20200928175229.GA2202997@kroah.com> References: <1601301410240130@kroah.com> <20200928152941.GA66303@lobo> <20200928173144.GA2042505@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928173144.GA2042505@kroah.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Sep 28, 2020 at 07:31:44PM +0200, Greg KH wrote: > 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? I dug it up: ee1dfad5325f ("dm: fix bio splitting and its bio completion order for regular IO")