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=-8.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 72DE8C4338F for ; Tue, 10 Aug 2021 23:53:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F3B6D60FDA for ; Tue, 10 Aug 2021 23:53:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org F3B6D60FDA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 49CA76B0071; Tue, 10 Aug 2021 19:53:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 44D166B0072; Tue, 10 Aug 2021 19:53:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33B268D0001; Tue, 10 Aug 2021 19:53:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0191.hostedemail.com [216.40.44.191]) by kanga.kvack.org (Postfix) with ESMTP id 177576B0071 for ; Tue, 10 Aug 2021 19:53:38 -0400 (EDT) Received: from smtpin33.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id AEA7B8249980 for ; Tue, 10 Aug 2021 23:53:37 +0000 (UTC) X-FDA: 78460825674.33.0DF059D Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf10.hostedemail.com (Postfix) with ESMTP id 34621600BF38 for ; Tue, 10 Aug 2021 23:53:37 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 3A2FC60F41; Tue, 10 Aug 2021 23:53:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628639616; bh=gIFTc28B8SpNx71E0ZiZSdOFkZTRdREEDo6Iel/oF5Y=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=e6gEjmUT1tihohjm84mgXkAz+XMaSyQcX2J08SpkcW6Wta2s4dfb3Cc8DewRtcE8i tbklr64lIm4U7zbony9ilV7Ih4FKiVa0GdEFC2Sc08iWzQc0QfhTr/pPhcL73K4b1M Nox5JpLHeZIxvfCgod9mokHuNZNsrAuG3mL90Y9L2Yt6o6DdP5g3RVndGEc2C0IljQ sEGp4IUnCbkQubMFYag3FdjGdryowKmSKbbbiD8cOUcXpojoj4ZDCejSySAltMd7fV Re6aj0rctELxMdewqOz1+3E8iJgA2IDFpMYjWK7uEjY6nfnC8Rw2aDlAzH1ahEg3mO orUONG+/MJ0Fw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 09BA05C048D; Tue, 10 Aug 2021 16:53:36 -0700 (PDT) Date: Tue, 10 Aug 2021 16:53:36 -0700 From: "Paul E. McKenney" To: Vlastimil Babka Cc: Mike Galbraith , Qian Cai , Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Jann Horn Subject: Re: [PATCH v4 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Message-ID: <20210810235336.GQ4126399@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20210805152000.12817-1-vbabka@suse.cz> <20210805152000.12817-30-vbabka@suse.cz> <0b36128c-3e12-77df-85fe-a153a714569b@quicinc.com> <2eb3cf340716c40f03a0a342ab40219b3d1de195.camel@gmx.de> <20210810203123.GB190765@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 34621600BF38 Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=e6gEjmUT; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of "SRS0=bEI5=NB=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" designates 198.145.29.99 as permitted sender) smtp.mailfrom="SRS0=bEI5=NB=paulmck-ThinkPad-P17-Gen-1.home=paulmck@kernel.org" X-Stat-Signature: jtdogtdd44nwn6j4azpxhg9fd6u6gwnx X-HE-Tag: 1628639617-279867 Content-Transfer-Encoding: quoted-printable 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 Wed, Aug 11, 2021 at 12:36:00AM +0200, Vlastimil Babka wrote: > On 8/10/2021 10:31 PM, Paul E. McKenney wrote: > > On Tue, Aug 10, 2021 at 01:47:42PM +0200, Mike Galbraith wrote: > >> On Tue, 2021-08-10 at 11:03 +0200, Vlastimil Babka wrote: > >>> On 8/9/21 3:41 PM, Qian Cai wrote: > >>>>> =A0 > >>>>> +static DEFINE_MUTEX(flush_lock); > >>>>> +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); > >>>>> + > >>>>> =A0static void flush_all(struct kmem_cache *s) > >>>>> =A0{ > >>>>> -=A0=A0=A0=A0=A0=A0=A0on_each_cpu_cond(has_cpu_slab, flush_cpu_sl= ab, s, 1); > >>>>> +=A0=A0=A0=A0=A0=A0=A0struct slub_flush_work *sfw; > >>>>> +=A0=A0=A0=A0=A0=A0=A0unsigned int cpu; > >>>>> + > >>>>> +=A0=A0=A0=A0=A0=A0=A0mutex_lock(&flush_lock); > >>>> > >>>> Vlastimil, taking the lock here could trigger a warning during mem= ory offline/online due to the locking order: > >>>> > >>>> slab_mutex -> flush_lock > >>>> > >>>> [=A0=A0 91.374541] WARNING: possible circular locking dependency d= etected > >>>> [=A0=A0 91.381411] 5.14.0-rc5-next-20210809+ #84 Not tainted > >>>> [=A0=A0 91.387149] -----------------------------------------------= ------- > >>>> [=A0=A0 91.394016] lsbug/1523 is trying to acquire lock: > >>>> [=A0=A0 91.399406] ffff800018e76530 (flush_lock){+.+.}-{3:3}, at: = flush_all+0x50/0x1c8 > >>>> [=A0=A0 91.407425] > >>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 but task is already hol= ding lock: > >>>> [=A0=A0 91.414638] ffff800018e48468 (slab_mutex){+.+.}-{3:3}, at: = slab_memory_callback+0x44/0x280 > >>>> [=A0=A0 91.423603] > >>>> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 which lock already depe= nds on the new lock. > >>>> > >>> > >>> OK, managed to reproduce in qemu and this fixes it for me on top of > >>> next-20210809. Could you test as well, as your testing might be mor= e > >>> comprehensive? I will format is as a fixup for the proper patch in = the series then. > >> > >> As it appeared it should, moving cpu_hotplug_lock outside slab_mutex= in > >> kmem_cache_destroy() on top of that silenced the cpu offline gripe. > >=20 > > And this one got rid of the remainder of the deadlock, but gets me th= e > > splat shown at the end of this message. So some sort of middle groun= d > > may be needed. > >=20 > > (Same reproducer as in my previous reply to Vlastimil.) > >=20 > > Thanx, Paul > >=20 > >> --- > >> mm/slab_common.c | 2 ++ > >> mm/slub.c | 2 +- > >> 2 files changed, 3 insertions(+), 1 deletion(-) > >> > >> --- a/mm/slab_common.c > >> +++ b/mm/slab_common.c > >> @@ -502,6 +502,7 @@ void kmem_cache_destroy(struct kmem_cach > >> if (unlikely(!s)) > >> return; > >> > >> + cpus_read_lock(); > >> mutex_lock(&slab_mutex); > >> > >> s->refcount--; > >> @@ -516,6 +517,7 @@ void kmem_cache_destroy(struct kmem_cach > >> } > >> out_unlock: > >> mutex_unlock(&slab_mutex); > >> + cpus_read_unlock(); > >> } > >> EXPORT_SYMBOL(kmem_cache_destroy); > >> > >> --- a/mm/slub.c > >> +++ b/mm/slub.c > >> @@ -4234,7 +4234,7 @@ int __kmem_cache_shutdown(struct kmem_ca > >> int node; > >> struct kmem_cache_node *n; > >> > >> - flush_all(s); > >> + flush_all_cpus_locked(s); > >> /* Attempt to free all objects */ > >> for_each_kmem_cache_node(s, node, n) { > >> free_partial(s, n); > >=20 > > [ 602.539109] ------------[ cut here ]------------ > > [ 602.539804] WARNING: CPU: 3 PID: 88 at kernel/cpu.c:335 lockdep_as= sert_cpus_held+0x29/0x30 >=20 > So this says the assert failed and we don't have the cpus_read_lock(), = right, but... >=20 > > [ 602.540940] Modules linked in: > > [ 602.541377] CPU: 3 PID: 88 Comm: torture_shutdow Not tainted 5.14.= 0-rc5-next-20210809+ #3299 > > [ 602.542536] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.13.0-2.modu= le_el8.5.0+746+bbd5d70c 04/01/2014 > > [ 602.543786] RIP: 0010:lockdep_assert_cpus_held+0x29/0x30 > > [ 602.544524] Code: 00 83 3d 4d f1 a4 01 01 76 0a 8b 05 4d 23 a5 01 = 85 c0 75 01 c3 be ff ff ff ff 48 c7 c7 b0 86 66 a3 e8 9b 05 c9 00 85 c0 7= 5 ea <0f> 0b c3 0f 1f 40 00 41 57 41 89 ff 41 56 4d 89 c6 41 55 49 89 cd > > [ 602.547051] RSP: 0000:ffffb382802efdb8 EFLAGS: 00010246 > > [ 602.547783] RAX: 0000000000000000 RBX: ffffa23301a44000 RCX: 00000= 00000000001 > > [ 602.548764] RDX: 0000000000000001 RSI: ffffffffa335f5c0 RDI: fffff= fffa33adbbf[ 602.549747] RBP: ffffa23301a44000 R08: ffffa23302810000 R09= : 974cf0ba5c48ad3c > > [ 602.550727] R10: ffffb382802efe78 R11: 0000000000000001 R12: ffffa= 23301a44000[ 602.551709] R13: 00000000000249c0 R14: 00000000ffffffff R15= : 0000000fffffffe0 > > [ 602.552694] FS: 0000000000000000(0000) GS:ffffa2331f580000(0000) = knlGS:0000000000000000 > > [ 602.553805] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 602.554606] CR2: 0000000000000000 CR3: 0000000017222000 CR4: 00000= 000000006e0 > > [ 602.555601] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000= 00000000000 > > [ 602.556590] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 00000= 00000000400 > > [ 602.557585] Call Trace: > > [ 602.557927] flush_all_cpus_locked+0x29/0x140 > > [ 602.558535] __kmem_cache_shutdown+0x26/0x200 > > [ 602.559145] ? lock_is_held_type+0xd6/0x130 > > [ 602.559739] ? torture_onoff+0x260/0x260 > > [ 602.560284] kmem_cache_destroy+0x38/0x110 >=20 > It should have been taken here. I don't understand. It's as if only the > mm/slub.c was patched by Mike's patch, but mm/slab_common.c not? You know, you would think that I would have learned how to reliably apply a patch by now. Apparently not this morning. Anyway, right in one! I will try again with the full patch later. Thanx, Paul > > [ 602.560859] rcu_torture_cleanup.cold.36+0x192/0x421 > > [ 602.561539] ? wait_woken+0x60/0x60 > > [ 602.562035] ? torture_onoff+0x260/0x260 > > [ 602.562591] torture_shutdown+0xdd/0x1c0 > > [ 602.563131] kthread+0x132/0x160 > > [ 602.563592] ? set_kthread_struct+0x40/0x40 > > [ 602.564172] ret_from_fork+0x22/0x30 > > [ 602.564696] irq event stamp: 1307 > > [ 602.565161] hardirqs last enabled at (1315): []= __up_console_sem+0x4d/0x50 > > [ 602.566321] hardirqs last disabled at (1324): []= __up_console_sem+0x32/0x50 > > [ 602.567479] softirqs last enabled at (1304): []= __do_softirq+0x311/0x473 > > [ 602.568616] softirqs last disabled at (1299): []= irq_exit_rcu+0xe8/0xf0 > > [ 602.569735] ---[ end trace 26fd643e1df331c9 ]--- > >=20 >=20