From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (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 AC2262EBB8D for ; Thu, 16 Jul 2026 03:19:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784171942; cv=none; b=r+Aw7JJ0FkbogvdnNNUV4jEnMHcMlQc76ammnLpzVObk0eRgfyKPTnmiYvsDph4GJSnnuoxbrXuyz+/iPrl1WS4Nhrbj1Y6Ey9IgpTau+ssNqjHbYO/BcOC2i7pjJol9ak6Oc3/k6qw9NMpJ0YWIxU+JaeoiLKlbdKJQN0ml4jA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784171942; c=relaxed/simple; bh=ZtzyzWp9Hgr1m5lQFzzbe5uY6ndBEnGQz9PtUl9w+4Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nf0kRCQnC6eVT2cUHo3fxtxZOZ4Lu3oMdR8yQ6EB+2I5KGBQDnWzNbyjAZqtix8U8/hHTBW1pN1P5ZGI98HTE0UN41gH5bwuN5g17dNlSzUbw5FcI9pJjzt33/CIwJGY9jiS+nzcFceJaZpXV9U0EjI+p5VphWxsBBpME4PVeYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=oAjDD2Dp; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="oAjDD2Dp" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784171938; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F2+wiVXqFER56suiYoyluTh0yWbLBUPuPSa5i4pNZtw=; b=oAjDD2DpPLx2y9QSnMyAFBPveYRCeMghBcqkdxtvOR9T/UEs6XEs8tW+NrTh/JNIun8I5D 2js20WvXL/faUC9EDv3qfo0IFZ4OfkBlNIb8a2so502eCSH0uFq85rCsvSNeRGpbkMO3FM aEpKNADeVm/Jkm8GTBmu+fA/Tr1t49k= From: Ridong To: Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Andrew Morton , Chris Li , Kairui Song Cc: Muchun Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , David Hildenbrand , Qi Zheng , Lorenzo Stoakes , Axel Rasmussen , Yuanchu Xie , Wei Xu , Davidlohr Bueso , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ridong Chen , Ridong Chen , stable@vger.kernel.org Subject: [PATCH v2 2/2] mm: vmscan: fix node reclaim ignoring swappiness parameter Date: Thu, 16 Jul 2026 11:17:29 +0800 Message-Id: <20260716031729.1064007-3-ridong.chen@linux.dev> In-Reply-To: <20260716031729.1064007-1-ridong.chen@linux.dev> References: <20260716031729.1064007-1-ridong.chen@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Ridong Chen sc_swappiness() had two separate definitions depending on CONFIG_MEMCG. The !CONFIG_MEMCG variant simply returned vm_swappiness, ignoring the proactive_swappiness value passed through scan_control. This caused the swappiness parameter written to /sys/devices/system/node/nodeX/reclaim to have no effect when CONFIG_MEMCG is disabled. Fix this by consolidating sc_swappiness() into a single definition that checks sc->proactive_swappiness first, then falls back to mem_cgroup_swappiness() which already handles both CONFIG_MEMCG and !CONFIG_MEMCG. Before fix (swappiness=max ignored, mostly file pages reclaimed): # cat /proc/sys/vm/swappiness 60 # cat /proc/vmstat | grep pgsteal pgsteal_kswapd 0 pgsteal_direct 0 pgsteal_khugepaged 0 pgsteal_proactive 1840 pgsteal_anon 25 pgsteal_file 1815 # echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim # cat /proc/vmstat | grep pgsteal pgsteal_kswapd 0 pgsteal_direct 0 pgsteal_khugepaged 0 pgsteal_proactive 18013 pgsteal_anon 337 pgsteal_file 17676 After fix (swappiness=max honored, anon pages reclaimed as expected): # cat /proc/vmstat | grep pgsteal pgsteal_kswapd 0 pgsteal_direct 0 pgsteal_khugepaged 0 pgsteal_proactive 0 pgsteal_anon 0 pgsteal_file 0 # echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim # cat /proc/vmstat | grep pgsteal pgsteal_kswapd 0 pgsteal_direct 0 pgsteal_khugepaged 0 pgsteal_proactive 16283 pgsteal_anon 16283 pgsteal_file 0 Cc: stable@vger.kernel.org # 6.17+ Fixes: b980077899ea ("mm: introduce per-node proactive reclaim interface") Signed-off-by: Ridong Chen Acked-by: Johannes Weiner Reviewed-by: Barry Song --- mm/vmscan.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 986dde8e7429..bd71595c8b2b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -199,6 +199,13 @@ struct scan_control { */ int vm_swappiness = 60; +static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg) +{ + if (sc->proactive && sc->proactive_swappiness) + return *sc->proactive_swappiness; + return mem_cgroup_swappiness(memcg); +} + #ifdef CONFIG_MEMCG /* Returns true for reclaim through cgroup limits or cgroup interfaces. */ @@ -239,13 +246,6 @@ static bool writeback_throttling_sane(struct scan_control *sc) #endif return false; } - -static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg) -{ - if (sc->proactive && sc->proactive_swappiness) - return *sc->proactive_swappiness; - return mem_cgroup_swappiness(memcg); -} #else static bool cgroup_reclaim(struct scan_control *sc) { @@ -261,11 +261,6 @@ static bool writeback_throttling_sane(struct scan_control *sc) { return true; } - -static int sc_swappiness(struct scan_control *sc, struct mem_cgroup *memcg) -{ - return READ_ONCE(vm_swappiness); -} #endif static void set_task_reclaim_state(struct task_struct *task, -- 2.34.1