From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2E498379C5F; Sun, 26 Jul 2026 20:55:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785099361; cv=none; b=OxnlinAQN9uIKk5pJZgREkRJLbuQPbIwe2EIG7LKW7podV44MgJKK7d0/Bz7Ny1YQ7xii9Fa22sBB4Ae6sUip8pbB7mMHo0ww8flsgYuxeBtHAefBD1lphUSngJSdmLCl3DhemPp3MZLAYbebz0mEgShzdAFpC8eXVURPMHcUm4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785099361; c=relaxed/simple; bh=AbdV9VjhE6LTaOq0QiOaDkZKgquyYn4aQm+lx4mTY2o=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=q+OebAh/TK9p/xcWGDo69dJfOzVWjK3+hxRvsCj/2/rYweP+9Vo0QK153wPeYYADAO6sbTl/0/+1JbWmmKBaGAxdAhh9GWflN6Olc3kPkpUOe2mgpk40n+gHpyO4FPyYxlXNUJoflG5umooJ75lilXPDggltiTNWCMz0nfljP7U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mcbZP66i; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mcbZP66i" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83D4C1F000E9; Sun, 26 Jul 2026 20:55:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785099359; bh=Cy1jhkVJMikuaizngOmkeHoHcCAWhI3GKKlTl+pKDaY=; h=From:To:Cc:Subject:Date; b=mcbZP66iHAvO7Cktqkzc9+AqeuV8RWgPJ5gtYgefh4R164h5kjvdkM3rU7tKU7cWW dPxWFDuItoovOEY4JdMDkayHK9EzSfkYbWIib/xDP/R956LgfAZMrnvTrlPzC7uOO8 dnYo8kYcuFAnJeqL+Po92OFFoLcu2sdbnN1ZzXTRYanbemJGHEIwBiExnMGQ12KkP/ Q9oylu9KQudphgD/Pc4+9PwbpZ4wFaBXSCej8aLZU7Qcf+ZJnkkhXnMqD4whsmiq/t FErlGOYnWiXVYU/lKnCmJqw5eNuWybGXUQTcXczHNpe0Uhq2+Btjdsdo8C8vRpuEyi k/yV4yJfl4tbw== From: SJ Park To: Cc: SJ Park , stable@vger.kernel.org, Andrew Morton , Honggyu Kim , Hyeongtak Ji , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH] mm/damon: adjust isolated pages stat for DAMOS_MIGRATE_{HOT,COLD} Date: Sun, 26 Jul 2026 13:55:46 -0700 Message-ID: <20260726205548.2287-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Callers of migrate_pages() should adjust NR_MIGRATED_{ANON,FILE} for isolations and putback of the folios. That for migration succeeded folios is done by migrate_pages(), in migrate_folio_done(). That for MR_DEMOTION reason is an exception though. DAMOS_MIGRATE_{HOT,COLD} call migrate_pages() but mistakenly not doing the stat adjustment. As a result, use of DAMOS_MIGRATE_{HOT,COLD} could corrupt the stat. It could confuse too_many_isolated(), make compaction and reclaim to behave in unexpected ways. The stat corruption can be reproduced and confirmed using DAMON user-space tool [1] on NUMA systems, like below. $ numactl --hardware available: 2 nodes (0-1) [...] $ sudo ./damo start --damos_action migrate_hot 1 $ sudo cat /proc/sys/vm/stat_refresh $ sudo dmesg [...] [ 80.215554] vmstat_refresh: nr_isolated_anon -5578 [ 80.216842] vmstat_refresh: nr_isolated_file -34400 This issue was discovered [2] by Sashiko. [1] https://github.com/damonitor/damo [2] https://lore.kernel.org/20260726164356.87940-1-sj@kernel.org Fixes: b51820ebea65 ("mm/damon/paddr: introduce DAMOS_MIGRATE_COLD action for demotion") Cc: # 6.11.x Signed-off-by: SJ Park --- mm/damon/ops-common.c | 2 ++ mm/damon/paddr.c | 2 ++ mm/damon/vaddr.c | 3 ++- 3 files changed, 6 insertions(+), 1 deletion(-) diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c index e59f77eca83b2..9809fa12b09a8 100644 --- a/mm/damon/ops-common.c +++ b/mm/damon/ops-common.c @@ -374,6 +374,8 @@ static unsigned int damon_migrate_folio_list(struct list_head *folio_list, while (!list_empty(folio_list)) { folio = lru_to_folio(folio_list); list_del(&folio->lru); + node_stat_sub_folio(folio, NR_ISOLATED_ANON + + folio_is_file_lru(folio)); folio_putback_lru(folio); } diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c index 5a6a78054784a..5c6c3a597fd0b 100644 --- a/mm/damon/paddr.c +++ b/mm/damon/paddr.c @@ -346,6 +346,8 @@ static unsigned long damon_pa_migrate(struct damon_region *r, if (!folio_isolate_lru(folio)) goto put_folio; + node_stat_add_folio(folio, NR_ISOLATED_ANON + + folio_is_file_lru(folio)); list_add(&folio->lru, &folio_list); put_folio: addr += folio_size(folio); diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c index 4976775fe2762..0648400b2d65b 100644 --- a/mm/damon/vaddr.c +++ b/mm/damon/vaddr.c @@ -627,7 +627,8 @@ static void damos_va_migrate_dests_add(struct folio *folio, isolate: if (!folio_isolate_lru(folio)) return; - + node_stat_add_folio(folio, NR_ISOLATED_ANON + + folio_is_file_lru(folio)); list_add(&folio->lru, &migration_lists[i]); } base-commit: 1e15fbef3a3c465a6a2db0f38e3980d75420bd6d -- 2.47.3