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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1783761157; 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=txHSRzd4Tyll9+u/6ycOBWsZl1BLLa4J8x2YbM2XGjY=; b=VrP+biTWejQyufZrrsBWkZdS4Y44CAMVPA1t1uvFTYzGQyvivpH+acxA0fsBkOrv3yFNbW FwCVtuUgwOZrbyWhMHC7vjl3alqLcXGVBegb3WalKIIMUstbUpLhCpFJBQSYSRIJevONsD J8QqLiojiVVSfyKBPJ68zkmaZzViM9Q= From: Ridong Chen To: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Chris Li , Kairui Song , David Hildenbrand , Barry Song , Yuanchu Xie Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, ridong.chen@linux.dev, Ridong Chen Subject: [PATCH 2/2] mm: vmscan: fix node reclaim ignoring swappiness parameter Date: Sat, 11 Jul 2026 17:11:57 +0800 Message-ID: <20260711091157.306070-3-ridong.chen@linux.dev> In-Reply-To: <20260711091157.306070-1-ridong.chen@linux.dev> References: <20260711091157.306070-1-ridong.chen@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: BF632120005 X-Stat-Signature: x5wbeqezitozdue1cecojobmd4ipfo8p X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1783761158-167569 X-HE-Meta: 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 DgiJwtmG kOOsUAKuLgvfNfKLzVDMaV3zrxtZjgDEQTt89Aksz6owI1KSAn3Rm8/gp6pAxwWhDoV5/txqxO3QM3BYaKV0bdWptTO9ld6q/0q0/WXXY4e3hvwf3p3yqHrqSL3f993bYLYgRi919DhNF91tgpWLWpymsz1117eANvhdSGc/y2LPa4eVjCTe+tHVw9R2TqgP/KUTJIuYRnrwcgkBsR5UMdLfMeLvvGOkyC1lJ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 Fixes: 68cd9050d871 ("mm: add swappiness= arg to memory.reclaim") Signed-off-by: Ridong Chen --- mm/vmscan.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 35c3bb15ae96..5271bd023c1d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -198,6 +198,13 @@ 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. */ @@ -239,12 +246,6 @@ static bool writeback_throttling_sane(struct scan_control *sc) 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) { @@ -261,10 +262,6 @@ 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, -- 2.43.0