From patchwork Sat Feb 12 00:32:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 542394 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7EC2C4332F for ; Sat, 12 Feb 2022 00:32:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354407AbiBLAci (ORCPT ); Fri, 11 Feb 2022 19:32:38 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:34358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231404AbiBLAcd (ORCPT ); Fri, 11 Feb 2022 19:32:33 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36BF0D7E; Fri, 11 Feb 2022 16:32:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C740461D1F; Sat, 12 Feb 2022 00:32:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21B7AC340EB; Sat, 12 Feb 2022 00:32:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1644625950; bh=oeJKDJ1bkgfhW/gRKDnHsKnyYro9XJZrr1UCVplP8x8=; h=Date:To:From:In-Reply-To:Subject:From; b=JI3CFhY5yd/fKS0RMJJ43TIpMsBrIjlKm0fg/i4g7G2JOnoYMHJubValwr7wiK0lx 735CPj/Tu1mHo3FB2qJhe05aF37W+8TyPywe3O5HbSVdXO9TWfkTmisgzz/0cpZbyG rrOrWwpAXj0uy1EHYSW38hJPq2kNhhBJ43bemFVU= Date: Fri, 11 Feb 2022 16:32:29 -0800 To: vbabka@suse.cz, stable@vger.kernel.org, rientjes@google.com, riel@surriel.com, mhocko@suse.com, hughd@google.com, mgorman@suse.de, akpm@linux-foundation.org, patches@lists.linux.dev, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220211162756.9f8e8baef81183041ccfc16f@linux-foundation.org> Subject: [patch 3/5] mm: vmscan: remove deadlock due to throttling failing to make progress Message-Id: <20220212003230.21B7AC340EB@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mel Gorman Subject: mm: vmscan: remove deadlock due to throttling failing to make progress 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 This failure is specific to CONFIG_PREEMPT=n builds. 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. Link: https://lkml.kernel.org/r/20220203100326.GD3301@suse.de Fixes: d818fca1cac3 ("mm/vmscan: throttle reclaim and compaction when too may pages are isolated") Signed-off-by: Mel Gorman Debugged-by: Vlastimil Babka Reviewed-by: Vlastimil Babka Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Hugh Dickins Cc: Michal Hocko Cc: Rik van Riel Cc: Signed-off-by: Andrew Morton --- a/mm/vmscan.c~mm-vmscan-remove-deadlock-due-to-throttling-failing-to-make-progress +++ a/mm/vmscan.c @@ -1066,8 +1066,10 @@ void reclaim_throttle(pg_data_t *pgdat, * 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.