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 9E38FC433EF for ; Tue, 1 Feb 2022 22:53:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242079AbiBAWxA (ORCPT ); Tue, 1 Feb 2022 17:53:00 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:58992 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241098AbiBAWw7 (ORCPT ); Tue, 1 Feb 2022 17:52:59 -0500 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 sin.source.kernel.org (Postfix) with ESMTPS id D1515CE1AEA for ; Tue, 1 Feb 2022 22:52:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C45A1C340EB; Tue, 1 Feb 2022 22:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1643755976; bh=ZOXeNgTsvQgWAGc5i80QNw0QwW4vsgAARg4ZxFXoou0=; h=Date:To:From:Subject:From; b=xc3c0TDBvW14VQUz8bVnSzWRfXJocWgIb4iQgnjt1GjDPmqH3nXp5QkdOzh+dpyTT YfMrtM16ruxA+HeFDzbKMOW7EYaXWY+W0itWovNQOYy/BdWbSKZbLMkIcA5dn8+7Lc 86ahvyIU6n+BvwFsMZAmDtmRDiPxBcXDN5C0JDVA= Received: by hp1 (sSMTP sendmail emulation); Tue, 01 Feb 2022 14:52:54 -0800 Date: Tue, 01 Feb 2022 14:52:54 -0800 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: + mmmigrate-fix-establishing-demotion-target.patch added to -mm tree Message-Id: <20220201225254.C45A1C340EB@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 added to the -mm tree. Its filename is mmmigrate-fix-establishing-demotion-target.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mmmigrate-fix-establishing-demotion-target.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mmmigrate-fix-establishing-demotion-target.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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" Cc: Baolin Wang Cc: Dave Hansen Cc: Zi Yan Cc: Oscar Salvador Cc: Yang Shi Cc: Baolin Wang 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 @@ -3083,18 +3083,21 @@ 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 mmmigrate-fix-establishing-demotion-target.patch numa-balancing-add-page-promotion-counter.patch numa-balancing-optimize-page-placement-for-memory-tiering-system.patch memory-tiering-skip-to-scan-fast-memory.patch