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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E98EC433EF for ; Fri, 25 Mar 2022 01:33:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356334AbiCYBfE (ORCPT ); Thu, 24 Mar 2022 21:35:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357365AbiCYBdx (ORCPT ); Thu, 24 Mar 2022 21:33:53 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 678FC3DA66 for ; Thu, 24 Mar 2022 18:32:20 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 18EDCB82725 for ; Fri, 25 Mar 2022 01:32:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB649C340ED; Fri, 25 Mar 2022 01:32:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648171937; bh=7Uees5Qr4/e5SzPArRidgqC6gK1CvOrY5Ft02nG9JSU=; h=Date:To:From:Subject:From; b=EdwffoqokjJAvrTQ3VCnnL7LbHkXYGKpEHwTVfiPH7WhWGzOuUzdHxfRqxwoW92gm vCU79C9Z+U0UN2r8Rb54BljpMI3ypuC4ae8uoVo2PvVLBZ2mtEBKp8HlZyRCnWwlBe jSLPjZDO3xJl/+Fq4lIlG5qNRrl7ItGWu47c62wA= Date: Thu, 24 Mar 2022 18:32:17 -0700 To: mm-commits@vger.kernel.org, ziy@nvidia.com, zhongjiang-ali@linux.alibaba.com, xlpang@linux.alibaba.com, shy828301@gmail.com, osalvador@suse.de, mgorman@techsingularity.net, dave.hansen@linux.intel.com, baolin.wang@linux.alibaba.com, ying.huang@intel.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged] mmmigrate-fix-establishing-demotion-target.patch removed from -mm tree Message-Id: <20220325013217.AB649C340ED@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm,migrate: fix establishing demotion target has been removed from the -mm tree. Its filename was mmmigrate-fix-establishing-demotion-target.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Huang Ying Subject: mm,migrate: fix establishing demotion target In commit ac16ec835314 ("mm: migrate: support multiple target nodes demotion"), after the first demotion target node is found, we will continue to check the next candidate obtained via find_next_best_node(). This is to find all demotion target nodes with same NUMA distance. But one side effect of find_next_best_node() is that the candidate node returned will be set in "used" parameter, even if the candidate node isn't passed in the following NUMA distance checking, the candidate node will not be used as demotion target node for the following nodes. For example, for system as follows, node distances: node 0 1 2 3 0: 10 21 17 28 1: 21 10 28 17 2: 17 28 10 28 3: 28 17 28 10 when we establish demotion target node for node 0, in the first round node 2 is added to the demotion target node set. Then in the second round, node 3 is checked and failed because distance(0, 3) > distance(0, 2). But node 3 is set in "used" nodemask too. When we establish demotion target node for node 1, there is no available node. This is wrong, node 3 should be set as the demotion target of node 1. To fix this, if the candidate node is failed to pass the distance checking, it will be cleared in "used" nodemask. So that it can be used for the following node. The bug can be reproduced and fixed with this patch on a 2 socket server machine with DRAM and PMEM. Link: https://lkml.kernel.org/r/20220128055940.1792614-1-ying.huang@intel.com Fixes: ac16ec835314 ("mm: migrate: support multiple target nodes demotion") Signed-off-by: "Huang, Ying" Reviewed-by: Baolin Wang Cc: Baolin Wang Cc: Dave Hansen Cc: Zi Yan Cc: Oscar Salvador Cc: Yang Shi Cc: zhongjiang-ali Cc: Xunlei Pang Cc: Mel Gorman Signed-off-by: Andrew Morton --- mm/migrate.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/mm/migrate.c~mmmigrate-fix-establishing-demotion-target +++ a/mm/migrate.c @@ -3079,18 +3079,21 @@ static int establish_migrate_target(int if (best_distance != -1) { val = node_distance(node, migration_target); if (val > best_distance) - return NUMA_NO_NODE; + goto out_clear; } index = nd->nr; if (WARN_ONCE(index >= DEMOTION_TARGET_NODES, "Exceeds maximum demotion target nodes\n")) - return NUMA_NO_NODE; + goto out_clear; nd->nodes[index] = migration_target; nd->nr++; return migration_target; +out_clear: + node_clear(migration_target, *used); + return NUMA_NO_NODE; } /* _ Patches currently in -mm which might be from ying.huang@intel.com are