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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DAC14C433FE for ; Tue, 18 Jan 2022 11:07:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 11AAB6B0072; Tue, 18 Jan 2022 06:07:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0CA2F6B0073; Tue, 18 Jan 2022 06:07:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ED5236B0074; Tue, 18 Jan 2022 06:07:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0051.hostedemail.com [216.40.44.51]) by kanga.kvack.org (Postfix) with ESMTP id DF0D66B0072 for ; Tue, 18 Jan 2022 06:07:23 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9F568824C420 for ; Tue, 18 Jan 2022 11:07:23 +0000 (UTC) X-FDA: 79043131566.25.7DC65A3 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf16.hostedemail.com (Postfix) with ESMTP id 198CF18000A for ; Tue, 18 Jan 2022 11:07:22 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id A45041F3C0; Tue, 18 Jan 2022 11:07:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1642504041; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JBJ7AEiCYFHzM3I2zFFq4RgvGYZvYiPVEtyWVXWxLN0=; b=wNyJMttmonPq40jN9aGmLrlhMPB3R+0kJkRTmMtzp6FH6aKGo+p9S2IqQN5Nz0GXE/TEDb I0tTwbDhjJsATIFEu9ZbMeOKYujXAk8/RvcHYGB8obQ1uuDSqSJ2Z8Xofu7ULNbA1j1j/1 3CVCc1hyrRu96gEUDaSzUu2vy7KB1Lk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1642504041; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JBJ7AEiCYFHzM3I2zFFq4RgvGYZvYiPVEtyWVXWxLN0=; b=b12NQcJmVqQp1B4Dc9n1RQtxR7B3KuqqLyXdYIcS3ovaFM742ko1BTq816R3yVWYL+cnV0 FX/2ZX/eT2en9JBA== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 77D3013DC7; Tue, 18 Jan 2022 11:07:21 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id CsKRHGmf5mHSQQAAMHmgww (envelope-from ); Tue, 18 Jan 2022 11:07:21 +0000 Message-ID: Date: Tue, 18 Jan 2022 12:07:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] mm: slub: fix a deadlock warning in kmem_cache_destroy Content-Language: en-US To: Xin Long , Juri Lelli Cc: Sebastian Andrzej Siewior , Hyeonggon Yoo <42.hyeyoo@gmail.com>, LKML , linux-mm@kvack.org, Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Antoine Tenart , Clark Williams References: <388098b2c03fbf0a732834fc01b2d875c335bc49.1642170196.git.lucien.xin@gmail.com> <39a3470f-06ab-cf41-32e4-80edb249c7d3@suse.cz> <20220117131304.pdc3mfdowkzovw6q@localhost.localdomain> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 198CF18000A X-Stat-Signature: 6atqyk5jwmmk8jkiokx94wgqw8qr8a6j Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=wNyJMttm; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=b12NQcJm; dmarc=none; spf=pass (imf16.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam03 X-HE-Tag: 1642504042-165457 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/18/22 09:00, Xin Long wrote: > On Mon, Jan 17, 2022 at 9:13 PM Juri Lelli wrote: >> > >> > RHEL-8 kernel seems to be 4.18, unless RT uses a newer one. Could be some >> > silently relevant backport is missing? How about e.g. 59450bbc12be ("mm, >> > slab, slub: stop taking cpu hotplug lock") ? >> >> Hummm, looks like we have backported commit 59450bbc12be in RHEL-8. >> >> Xin Long, would you be able to check if you still see the lockdep splat >> with latest upstream RT? >> >> git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.16.y-rt > Hi, Juri, > > Thanks for sharing the RT kernel repo. > > I just tried with this kernel, and I couldn't reproduce it on my env. > But I don't see how the upstream RT kernel can avoid the call trace. > > As this warning was triggered when the system was shutting down, it might > not be reproduced on it due to some timing change. As it was caught by lockdep and not as a real deadlock, I think it should be indepenedent of a timing change. Lockdep will correlate potentially deadlock scenarios even if they don't really occur in the same time, AFAIK. But let's go back to: > Although cpu_hotplug_lock is a RWSEM, [a] will not block in there. But as > lockdep annotations are added for cpu_hotplug_lock, a deadlock warning > would be detected: Is it possible that upstream lockdep handles this RWSEM scenario properly and doesn't report it, but the RHEL kernel is missing some relevant lockdep fix? >> >> Thanks! >> Juri >>