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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,USER_AGENT_SANE_1 autolearn=unavailable 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 E6A84C4363E for ; Wed, 12 May 2021 19:37:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B71BD61289 for ; Wed, 12 May 2021 19:37:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1381005AbhELTdL (ORCPT ); Wed, 12 May 2021 15:33:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:45146 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242124AbhELR0x (ORCPT ); Wed, 12 May 2021 13:26:53 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3E32AAFC2; Wed, 12 May 2021 17:25:25 +0000 (UTC) Subject: Re: [PATCH 5.10 518/530] mm, slub: enable slub_debug static key when creating cache with explicit debug flags To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Oliver Glitta , David Rientjes , Christoph Lameter , Pekka Enberg , Joonsoo Kim , "Paul E. McKenney" , Andrew Morton , Linus Torvalds , Sasha Levin References: <20210512144819.664462530@linuxfoundation.org> <20210512144836.780038842@linuxfoundation.org> From: Vlastimil Babka Message-ID: <003ce4ee-304c-68cb-6871-cf01495438b6@suse.cz> Date: Wed, 12 May 2021 19:25:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/12/21 5:50 PM, Greg Kroah-Hartman wrote: > On Wed, May 12, 2021 at 05:35:28PM +0200, Vlastimil Babka wrote: >> On 5/12/21 4:50 PM, Greg Kroah-Hartman wrote: >> > From: Vlastimil Babka >> > >> > [ Upstream commit 1f0723a4c0df36cbdffc6fac82cd3c5d57e06d66 ] >> > >> > Commit ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") >> > introduced a static key to optimize the case where no debugging is >> > enabled for any cache. The static key is enabled when slub_debug boot >> > parameter is passed, or CONFIG_SLUB_DEBUG_ON enabled. >> > >> > However, some caches might be created with one or more debugging flags >> > explicitly passed to kmem_cache_create(), and the commit missed this. >> > Thus the debugging functionality would not be actually performed for >> > these caches unless the static key gets enabled by boot param or config. >> > >> > This patch fixes it by checking for debugging flags passed to >> > kmem_cache_create() and enabling the static key accordingly. >> > >> > Note such explicit debugging flags should not be used outside of >> > debugging and testing as they will now enable the static key globally. >> > btrfs_init_cachep() creates a cache with SLAB_RED_ZONE but that's a >> > mistake that's being corrected [1]. rcu_torture_stats() creates a cache >> > with SLAB_STORE_USER, but that is a testing module so it's OK and will >> > start working as intended after this patch. >> > >> > Also note that in case of backports to kernels before v5.12 that don't >> > have 59450bbc12be ("mm, slab, slub: stop taking cpu hotplug lock"), >> > static_branch_enable_cpuslocked() should be used. >> > >> > [1] https://lore.kernel.org/linux-btrfs/20210315141824.26099-1-dsterba@suse.com/ >> > >> > Link: https://lkml.kernel.org/r/20210315153415.24404-1-vbabka@suse.cz >> > Fixes: ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") >> > Signed-off-by: Vlastimil Babka >> > Reported-by: Oliver Glitta >> > Acked-by: David Rientjes >> > Cc: Christoph Lameter >> > Cc: Pekka Enberg >> > Cc: Joonsoo Kim >> > Cc: "Paul E. McKenney" >> > Signed-off-by: Andrew Morton >> > Signed-off-by: Linus Torvalds >> > Signed-off-by: Sasha Levin >> >> Uh, rather not release this to stable without the followup fix: >> https://lore.kernel.org/linux-mm/20210504120019.26791-1-vbabka@suse.cz/ > > Is that in Linus's tree yet? If so, what is the git id? No, it's in mmotm, so no git id yet, but should make it to Linus during 5.13 rc's. > thanks, > > greg k-h >