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 5C70EC433F5 for ; Thu, 3 Feb 2022 18:53:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 18E5C6B0072; Thu, 3 Feb 2022 13:53:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 13EA26B0074; Thu, 3 Feb 2022 13:53:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EFA046B0075; Thu, 3 Feb 2022 13:53:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0187.hostedemail.com [216.40.44.187]) by kanga.kvack.org (Postfix) with ESMTP id DCCBE6B0074 for ; Thu, 3 Feb 2022 13:53:55 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 95E46182751A3 for ; Thu, 3 Feb 2022 18:53:55 +0000 (UTC) X-FDA: 79102368030.11.D7FC281 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf25.hostedemail.com (Postfix) with ESMTP id 1AAB1A0002 for ; Thu, 3 Feb 2022 18:53:54 +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-out1.suse.de (Postfix) with ESMTPS id 86BE6210F6; Thu, 3 Feb 2022 18:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1643914433; 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=6ZJP+ciPjqfM4S/keVcfF2rFaprDcpYE6rpUF4+5Cns=; b=Jf1/mBEmjU1uji8Qw6aEV/9uOYlArp7zwFxpaGC5sPsXJZMQsPp0dw1DcM333C1s2m3ALn v3tKGUyDjNjdr11NUYvEEHi11Vd15KQaP8joqioZraXRdevuaTz20fzLWCcukWd7IQCLqi ihsz0yfgIlj5XorvSVpACMGMxHisSA8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1643914433; 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=6ZJP+ciPjqfM4S/keVcfF2rFaprDcpYE6rpUF4+5Cns=; b=zoxBBoAhCTkDPNfG99T9GZCrGXarYsaf9lwS2dCBNdeYhGWJCUE60lC6/o4k2RPM68axHe Fsp0IqDAahrT9qCw== 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 65433139FE; Thu, 3 Feb 2022 18:53:53 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Qq/6F8Ek/GGBZQAAMHmgww (envelope-from ); Thu, 03 Feb 2022 18:53:53 +0000 Message-ID: <2472c281-436c-d5f5-61d8-e5192e912ff1@suse.cz> Date: Thu, 3 Feb 2022 19:53:53 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH] mm: vmscan: remove deadlock due to throttling failing to make progress Content-Language: en-US To: Mel Gorman , Andrew Morton Cc: Hugh Dickins , Michal Hocko , Rik van Riel , Linux-MM , LKML References: <20220203100326.GD3301@suse.de> From: Vlastimil Babka In-Reply-To: <20220203100326.GD3301@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1AAB1A0002 X-Stat-Signature: oyftm7hr9mhnqdqs9j3zthjukhshgnqp Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b="Jf1/mBEm"; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=zoxBBoAh; dmarc=none; spf=pass (imf25.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.28 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspam-User: nil X-HE-Tag: 1643914434-510169 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 2/3/22 11:03, Mel Gorman wrote: > A soft lockup bug in kcompactd was reported in a private bugzilla with > the following visible in dmesg; > > [15980.045209][ C33] watchdog: BUG: soft lockup - CPU#33 stuck for 26s! [kcompactd0:479] > [16008.044989][ C33] watchdog: BUG: soft lockup - CPU#33 stuck for 52s! [kcompactd0:479] > [16036.044768][ C33] watchdog: BUG: soft lockup - CPU#33 stuck for 78s! [kcompactd0:479] > [16064.044548][ C33] watchdog: BUG: soft lockup - CPU#33 stuck for 104s! [kcompactd0:479] > > The machine had 256G of RAM with no swap and an earlier failed allocation > indicated that node 0 where kcompactd was run was potentially > unreclaimable; > > Node 0 active_anon:29355112kB inactive_anon:2913528kB active_file:0kB > inactive_file:0kB unevictable:64kB isolated(anon):0kB isolated(file):0kB > mapped:8kB dirty:0kB writeback:0kB shmem:26780kB shmem_thp: > 0kB shmem_pmdmapped: 0kB anon_thp: 23480320kB writeback_tmp:0kB > kernel_stack:2272kB pagetables:24500kB all_unreclaimable? yes > > Vlastimil Babka investigated a crash dump and found that a task migrating pages > was trying to drain PCP lists; > > PID: 52922 TASK: ffff969f820e5000 CPU: 19 COMMAND: "kworker/u128:3" > #0 [ffffaf4e4f4c3848] __schedule at ffffffffb840116d > #1 [ffffaf4e4f4c3908] schedule at ffffffffb8401e81 > #2 [ffffaf4e4f4c3918] schedule_timeout at ffffffffb84066e8 > #3 [ffffaf4e4f4c3990] wait_for_completion at ffffffffb8403072 > #4 [ffffaf4e4f4c39d0] __flush_work at ffffffffb7ac3e4d > #5 [ffffaf4e4f4c3a48] __drain_all_pages at ffffffffb7cb707c > #6 [ffffaf4e4f4c3a80] __alloc_pages_slowpath.constprop.114 at ffffffffb7cbd9dd > #7 [ffffaf4e4f4c3b60] __alloc_pages at ffffffffb7cbe4f5 > #8 [ffffaf4e4f4c3bc0] alloc_migration_target at ffffffffb7cf329c > #9 [ffffaf4e4f4c3bf0] migrate_pages at ffffffffb7cf6d15 > 10 [ffffaf4e4f4c3cb0] migrate_to_node at ffffffffb7cdb5aa > 11 [ffffaf4e4f4c3da8] do_migrate_pages at ffffffffb7cdcf26 > 12 [ffffaf4e4f4c3e88] cpuset_migrate_mm_workfn at ffffffffb7b859d2 > 13 [ffffaf4e4f4c3e98] process_one_work at ffffffffb7ac45f3 > 14 [ffffaf4e4f4c3ed8] worker_thread at ffffffffb7ac47fd > 15 [ffffaf4e4f4c3f10] kthread at ffffffffb7acbdc6 > 16 [ffffaf4e4f4c3f50] ret_from_fork at ffffffffb7a047e2 > > The root of the problem is that kcompact0 is not rescheduling on a CPU > while a task that has isolated a large number of the pages from the > LRU is waiting on kcompact0 to reschedule so the pages can be released. > While shrink_inactive_list() only loops once around too_many_isolated, > reclaim can continue without rescheduling if sc->skipped_deactivate == > 1 which could happen if there was no file LRU and the inactive anon list > was not low. > > Debugged-by: Vlastimil Babka > Signed-off-by: Mel Gorman Fixes: d818fca1cac3 ("mm/vmscan: throttle reclaim and compaction when too may pages are isolated") Reviewed-by: Vlastimil Babka > --- > mm/vmscan.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 090bfb605ecf..59b14e0d696c 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1066,8 +1066,10 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason) > * forward progress (e.g. journalling workqueues or kthreads). > */ > if (!current_is_kswapd() && > - current->flags & (PF_IO_WORKER|PF_KTHREAD)) > + current->flags & (PF_IO_WORKER|PF_KTHREAD)) { > + cond_resched(); > return; > + } > > /* > * These figures are pulled out of thin air. >