From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) (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 1ECEA3F0ABA for ; Fri, 10 Jul 2026 11:12:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783681970; cv=none; b=gJ3HbTtEM4uM6KpDrrzRh2m66PwowfeYJhx5JHFYWaaqhWHSRRolwfu/j2FIcMglwmL4FwTsYzewadx3J5laZLslOP5KE3z2PaWhbfFefEuKZBnQ2p/NfU62rXkrSmv7uDeaxXUATcsmqOuQSglr4B+FxazfTgBkmu7FxiredEo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783681970; c=relaxed/simple; bh=YAJmIcgFhuEkxoN+buq1tJmz160P3f3NKCnJHSyubrU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=hPMnhc+s7zL1pyXeFdP3Hq8+M0X7l6dAhgq4L5ec4Oh5GF3YqmpYJNAlG0akJOHArJZdZwsQgdvF+7hSl/GOhH0bZDRMidU9b4nQbD2uIOwJD9hXGf7dyFPIfJ3XnqW+70LA7XTzQYdgJld3nsQcT96sXMV8eRSU/rMZxTBgLqI= 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=IFqLqY3D; arc=none smtp.client-ip=95.215.58.182 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="IFqLqY3D" 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=1783681966; 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; bh=ngy3pMTw2oJe0xcoHveOCKAvtR5RPrFr2htiJZs9bhY=; b=IFqLqY3DAom4XvqaOjOErkF9/erqvA8chQ+Lvm+KxY9AN68SP4P+GyN8fmmYCaSu1887qi KZpk284BSdJmi+2Wm7GfxTubHbzT+HC4h6mpzd6uxoaNVIVToJSbX/IhiC0GLuaRGx3gPf wuONTmcM/XJf5DAxbyn0aAfYDwWyLFU= 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 , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ridong.chen@linux.dev, Ridong Chen Subject: [PATCH -next] memcg: move mem_cgroup_swappiness to memcontrol.h Date: Fri, 10 Jul 2026 19:12:24 +0800 Message-Id: <20260710111224.2355668-1-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 The per-memcg swappiness knob is v1-only; v2 always uses global vm_swappiness and ignores the per-cgroup field. Guard memcg->swappiness with CONFIG_MEMCG_V1, and move the helper to memcontrol.h where it belongs. No functional change for v1; v2-only kernels drop the unused field. Signed-off-by: Ridong Chen --- include/linux/memcontrol.h | 25 +++++++++++++++++++++++-- include/linux/swap.h | 19 ------------------- mm/memcontrol.c | 3 +-- 3 files changed, 24 insertions(+), 23 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index e1f46a0016fc..f59614956f96 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -239,8 +239,6 @@ struct mem_cgroup { */ bool oom_group; - int swappiness; - /* memory.events and memory.events.local */ struct cgroup_file events_file; struct cgroup_file events_local_file; @@ -318,6 +316,9 @@ struct mem_cgroup { /* List of events which userspace want to receive */ struct list_head event_list; spinlock_t event_list_lock; + + int swappiness; + #endif /* CONFIG_MEMCG_V1 */ struct mem_cgroup_per_node *nodeinfo[]; @@ -365,6 +366,9 @@ enum objext_flags { #define OBJEXTS_FLAGS_MASK (__NR_OBJEXTS_FLAGS - 1) +/* Defined in mm/vmscan.c; used by mem_cgroup_swappiness(). */ +extern int vm_swappiness; + #ifdef CONFIG_MEMCG /* * After the initialization objcg->memcg is always pointing at @@ -1440,6 +1444,23 @@ static inline void mem_cgroup_flush_workqueue(void) { } static inline int mem_cgroup_init(void) { return 0; } #endif /* CONFIG_MEMCG */ +static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) +{ +#ifdef CONFIG_MEMCG_V1 + /* Cgroup2 doesn't have per-cgroup swappiness */ + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) + return READ_ONCE(vm_swappiness); + + /* root ? */ + if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg)) + return READ_ONCE(vm_swappiness); + + return READ_ONCE(memcg->swappiness); +#else + return READ_ONCE(vm_swappiness); +#endif +} + /* * Extended information for slab objects stored as an array in page->memcg_data * if MEMCG_DATA_OBJEXTS is set. diff --git a/include/linux/swap.h b/include/linux/swap.h index 3f31b6a56788..f27e73f29195 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -366,7 +366,6 @@ extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, pg_data_t *pgdat, unsigned long *nr_scanned); extern unsigned long shrink_all_memory(unsigned long nr_pages); -extern int vm_swappiness; long remove_mapping(struct address_space *mapping, struct folio *folio); #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) @@ -530,25 +529,7 @@ static inline int add_swap_extent(struct swap_info_struct *sis, } #endif /* CONFIG_SWAP */ #ifdef CONFIG_MEMCG -static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) -{ - /* Cgroup2 doesn't have per-cgroup swappiness */ - if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) - return READ_ONCE(vm_swappiness); - - /* root ? */ - if (mem_cgroup_disabled() || mem_cgroup_is_root(memcg)) - return READ_ONCE(vm_swappiness); - - return READ_ONCE(memcg->swappiness); -} - void lru_reparent_memcg(struct mem_cgroup *memcg, struct mem_cgroup *parent, int nid); -#else -static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) -{ - return READ_ONCE(vm_swappiness); -} #endif #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 938f190a98fe..2d659b76cd77 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4174,11 +4174,10 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) #endif page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX); if (parent) { - WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent)); - page_counter_init(&memcg->memory, &parent->memory, memcg_on_dfl); page_counter_init(&memcg->swap, &parent->swap, false); #ifdef CONFIG_MEMCG_V1 + WRITE_ONCE(memcg->swappiness, mem_cgroup_swappiness(parent)); memcg->memory.track_failcnt = !memcg_on_dfl; WRITE_ONCE(memcg->oom_kill_disable, READ_ONCE(parent->oom_kill_disable)); page_counter_init(&memcg->kmem, &parent->kmem, false); -- 2.34.1