From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9E4B1D5171; Mon, 28 Oct 2024 23:52:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730159533; cv=none; b=R6VM0qCeSjXU4Gq9QISAwAjBJS8+rQyVKJN+ZqC/P9/8oF1pbxrws1ampKRKvlCYeGb1lQwskEaaTYQoLYplvpRvhiITO7nCgsbskWTS05FDL4Q3ikRaGAR4/2XAgybqsDUC0/b8u45L1uoM2SsIhpOv7WajNRNQqYTuX3bYRE4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730159533; c=relaxed/simple; bh=JQ/lrItjqcXm/4ktsrc19zrWcrH8BaO6JqbI7d3GTnQ=; h=Date:To:From:Subject:Message-Id; b=Nl5meNuvXebNbrYOPo2yd0J6DQCrbamOd68ToC67uktVY1bZorVHTZWWlIjBZDxGNI9yuuH/0S1FucQP/Sy/H16jQKHRYdyWg/Xt0ESIDOzzmZOckbJCUHTg+57RgBJD6LfedZdIdwRPs2Q2X7S6Pd2ZUy96gH3Qt/XW4hBTcv8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=cfzYzDj1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="cfzYzDj1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42146C4CEC3; Mon, 28 Oct 2024 23:52:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1730159532; bh=JQ/lrItjqcXm/4ktsrc19zrWcrH8BaO6JqbI7d3GTnQ=; h=Date:To:From:Subject:From; b=cfzYzDj1taYm1kyUe7izTNFgapsvhMD7OuYgFrHmBt+fkk/Ke5bjbFkdkOAeDsvLY RgqwL2YmQenFXDTZp5DNcoCCJa9mSpNd0j1scP8bZwEb+TruJdmPdeXjaIFH4okXGM 1xWZ1eX+S+MjKd6DqZ8wAHHFXkYLhOY3lJM5bXzY= Date: Mon, 28 Oct 2024 16:52:11 -0700 To: mm-commits@vger.kernel.org,ying.huang@intel.com,weixugc@google.com,stable@vger.kernel.org,shy828301@gmail.com,osalvador@suse.de,dave.hansen@linux.intel.com,gourry@gourry.net,akpm@linux-foundation.org From: Andrew Morton Subject: + vmscanmigrate-fix-double-decrement-on-node-stats-when-demoting-pages.patch added to mm-hotfixes-unstable branch Message-Id: <20241028235212.42146C4CEC3@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: vmscan,migrate: fix page count imbalance on node stats when demoting pages has been added to the -mm mm-hotfixes-unstable branch. Its filename is vmscanmigrate-fix-double-decrement-on-node-stats-when-demoting-pages.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/vmscanmigrate-fix-double-decrement-on-node-stats-when-demoting-pages.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 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 via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Gregory Price Subject: vmscan,migrate: fix page count imbalance on node stats when demoting pages Date: Fri, 25 Oct 2024 10:17:24 -0400 When numa balancing is enabled with demotion, vmscan will call migrate_pages when shrinking LRUs. migrate_pages will decrement the the node's isolated page count, leading to an imbalanced count when invoked from (MG)LRU code. The result is dmesg output like such: $ cat /proc/sys/vm/stat_refresh [77383.088417] vmstat_refresh: nr_isolated_anon -103212 [77383.088417] vmstat_refresh: nr_isolated_file -899642 This negative value may impact compaction and reclaim throttling. The following path produces the decrement: shrink_folio_list demote_folio_list migrate_pages migrate_pages_batch migrate_folio_move migrate_folio_done mod_node_page_state(-ve) <- decrement This path happens for SUCCESSFUL migrations, not failures. Typically callers to migrate_pages are required to handle putback/accounting for failures, but this is already handled in the shrink code. When accounting for migrations, instead do not decrement the count when the migration reason is MR_DEMOTION. As of v6.11, this demotion logic is the only source of MR_DEMOTION. Link: https://lkml.kernel.org/r/20241025141724.17927-1-gourry@gourry.net Fixes: 26aa2d199d6f ("mm/migrate: demote pages during reclaim") Signed-off-by: Gregory Price Reviewed-by: Yang Shi Cc: Dave Hansen Cc: Huang Ying Cc: Oscar Salvador Cc: Wei Xu Cc: Signed-off-by: Andrew Morton --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/migrate.c~vmscanmigrate-fix-double-decrement-on-node-stats-when-demoting-pages +++ a/mm/migrate.c @@ -1178,7 +1178,7 @@ static void migrate_folio_done(struct fo * not accounted to NR_ISOLATED_*. They can be recognized * as __folio_test_movable */ - if (likely(!__folio_test_movable(src))) + if (likely(!__folio_test_movable(src)) && reason != MR_DEMOTION) mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + folio_is_file_lru(src), -folio_nr_pages(src)); _ Patches currently in -mm which might be from gourry@gourry.net are vmscanmigrate-fix-double-decrement-on-node-stats-when-demoting-pages.patch