From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (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 DF746168BE for ; Sat, 26 Oct 2024 16:37:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729960652; cv=none; b=sgOL8Er7XTml+hRvewnSnA6UVKERbvbMy7RExp64modNJRIxuXso36yrDdkoDnJ26RQkTKTlshTYfDiD6+cynxDAd0pCWbdnKRN0TwsPk4fJ/5qg7CVNSAtXhlc0prEHcNEX+oNF/rw0ukP11eNkWNBTG0xih4n3Dv20a5Dvcu4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729960652; c=relaxed/simple; bh=JcpoZk3RoHBHOWSG0QF+MLHrkxvWSoXtLhQCXhkoulg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=kv3vNTsRSH+smS6sDb0twiWpj69eSHiGi3A7xN/WHgIpjYMB4r/kq/GU7jC+9ODg0QxUyznmBpWTcX7J7D13U8oQacdL5rb/KZnbwJzalNH/Od9+qrKyqinGCXhy5h+K78x1C5/6ArdkRoU6/el5knOn+NSxAE46rVPPZjk3G6g= 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=JwppYDbH; arc=none smtp.client-ip=91.218.175.182 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="JwppYDbH" 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=1729960647; 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=kDTFYQ4jfbUxBCetm9ZFD4nERqP1KIxH9DYbqDWNu3k=; b=JwppYDbH2Y4GmKniz7qVDqFGFp1tsToZx/rxO0MEc2PqpYqIqAAhWWcca8GGeF3aCjvw9q e2B5pQKYY4kcnmMwPOE2WBXhtzF9a4jmTIGUkmGP4RqDiDN6Nl49PuKHBc2UOZeAtx7GNE E8+8oNOLfm9juAowpJAw1mYzw11TBc4= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Hugh Dickins , Yosry Ahmed , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team , Yu Zhao Subject: [PATCH v2] memcg: workingset: remove folio_memcg_rcu usage Date: Sat, 26 Oct 2024 09:37:07 -0700 Message-ID: <20241026163707.2479526-1-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT The function workingset_activation() is called from folio_mark_accessed() with the guarantee that the given folio can not be freed under us in workingset_activation(). In addition, the association of the folio and its memcg can not be broken here because charge migration is no more. There is no need to use folio_memcg_rcu. Simply use folio_memcg_charged() because that is what this function cares about. Signed-off-by: Shakeel Butt Suggested-by: Yu Zhao --- Andrew, please put this patch after charge migration deprecation series. Changes since v1: - Fix for mem_cgroup_disabled(). (Yu Zhao) include/linux/memcontrol.h | 35 ----------------------------------- mm/workingset.c | 14 ++------------ 2 files changed, 2 insertions(+), 47 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 932534291ca2..89a1e9f10e1b 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -443,35 +443,6 @@ static inline bool folio_memcg_charged(struct folio *folio) return __folio_memcg(folio) != NULL; } -/** - * folio_memcg_rcu - Locklessly get the memory cgroup associated with a folio. - * @folio: Pointer to the folio. - * - * This function assumes that the folio is known to have a - * proper memory cgroup pointer. It's not safe to call this function - * against some type of folios, e.g. slab folios or ex-slab folios. - * - * Return: A pointer to the memory cgroup associated with the folio, - * or NULL. - */ -static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio) -{ - unsigned long memcg_data = READ_ONCE(folio->memcg_data); - - VM_BUG_ON_FOLIO(folio_test_slab(folio), folio); - - if (memcg_data & MEMCG_DATA_KMEM) { - struct obj_cgroup *objcg; - - objcg = (void *)(memcg_data & ~OBJEXTS_FLAGS_MASK); - return obj_cgroup_memcg(objcg); - } - - WARN_ON_ONCE(!rcu_read_lock_held()); - - return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK); -} - /* * folio_memcg_check - Get the memory cgroup associated with a folio. * @folio: Pointer to the folio. @@ -1084,12 +1055,6 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio) return NULL; } -static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio) -{ - WARN_ON_ONCE(!rcu_read_lock_held()); - return NULL; -} - static inline struct mem_cgroup *folio_memcg_check(struct folio *folio) { return NULL; diff --git a/mm/workingset.c b/mm/workingset.c index 4b58ef535a17..a4705e196545 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -591,22 +591,12 @@ void workingset_refault(struct folio *folio, void *shadow) */ void workingset_activation(struct folio *folio) { - struct mem_cgroup *memcg; - - rcu_read_lock(); /* * Filter non-memcg pages here, e.g. unmap can call * mark_page_accessed() on VDSO pages. - * - * XXX: See workingset_refault() - this should return - * root_mem_cgroup even for !CONFIG_MEMCG. */ - memcg = folio_memcg_rcu(folio); - if (!mem_cgroup_disabled() && !memcg) - goto out; - workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio)); -out: - rcu_read_unlock(); + if (mem_cgroup_disabled() || folio_memcg_charged(folio)) + workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio)); } /* -- 2.43.5