From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D593A541E4E; Thu, 15 Oct 2026 18:15:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792088155; cv=none; b=VU7pNkxXcHhjpVqf2ra3rzYhOPsSQv+D43OpoKlZhOnp87lFRsjz3eM8H0Y2+20UH4yraPxTIX4M0p+8/pO2DJvGL0zx81/I0DZG6cwnh022M/epu5juTVV+mO/ZHMPsWWR+j5Lx6sGOqVp1qz1VJFpT000vi6dH8e1WbQJGQ8Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792088155; c=relaxed/simple; bh=Tgv6BaPO00+S97jAlKTn6xh90zKsXielMTf93zwSMVo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=G0UFu89fDLHaTPDcvL8GPjqM3+FFMHhK+7wwUuf7qGrFXAmzPMO63NQd03OzzzarjZQHEd2kML28BQkDaVALGkGzIyHF7Cpz9odjVvilKRAvYsSCDVmVRztTNad+IA7xHM6xMtoCVjJGVBToFXv5qtGT7PvMG4uxtmb4fHKlQDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eMg02pV0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eMg02pV0" Received: by smtp.kernel.org (Postfix) with ESMTPS id 545AAC2BD04; Thu, 15 Oct 2026 18:15:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1792088155; bh=Tgv6BaPO00+S97jAlKTn6xh90zKsXielMTf93zwSMVo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=eMg02pV0j2JCWPb5cuVkzKt2xEl4QphaZGbfI/lXaJw8KGG5JF9kkE4cie2WNKuB2 ofMM9t9xZVswRKoTmAlE5gSYjt/feGOAMlzk4KWDxJm3/LFKPMlF0qrNNB4RIGpdGy +lrd35d8Yp9f03o1mV4dfGhXNBNHkC3wwkVlYJfzL1TWuU2PipcDsrI20lzokMVou1 OcvvHleFUSgFEjXRvr5kLNcPYQAp9RRUmxfkEe7dEPBxsiwZhIh3VzvrbL+9uN7nYH oPMQlItj9qAkIBXzJpvArrW+JkSsIQ440+7kvd+N8beNa4W0v/MgHAftlWM5C+6/bM t1Q5JjM/s9WpA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36382CCA467; Thu, 15 Oct 2026 18:15:55 +0000 (UTC) From: Kairui Song via B4 Relay Date: Fri, 16 Oct 2026 02:15:52 +0800 Subject: [PATCH v4 03/17] mm/memcg: add folio-based lruvec live helper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261016-mglru-fg-v4-3-2106750c0bfa@tencent.com> References: <20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com> In-Reply-To: <20261016-mglru-fg-v4-0-2106750c0bfa@tencent.com> To: linux-mm@kvack.org, "Liam R. Howlett" , SJ Park Cc: Andrew Morton , Johannes Weiner , Muchun Song , Qi Zheng , Ying Huang , Chris Li , Baoquan He , Nico Pache , Usama Arif , Michal Hocko , Roman Gushchin , Shakeel Butt , David Hildenbrand , Lorenzo Stoakes , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Vlastimil Babka , Suren Baghdasaryan , Kemeng Shi , Nhat Pham , Youngjun Park , Zi Yan , Gregory Price , "Matthew Wilcox (Oracle)" , Baolin Wang , Ryan Roberts , Dev Jain , Lance Yang , Hugh Dickins , David Rientjes , Yu Zhao , Vernon Yang , Zicheng Wang , Chen Ridong , Tal Zussman , Kairui Song , Xiang Liu , Ehab Ababneh , zhaozhengzhuo , Lian Wang , Kunwu Chan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, Kairui Song X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1792088152; l=2034; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=bqSj6GEUFE1ch4tTEQEPZOkssBWYsWV/WhQc/GCJ0Bs=; b=ade8dgVk/QLtMdvzfHEj3EebA82ilil4wqag8aQYk8TBs2jVnr7PYCpkRECMbBvrjTfV5YSLN PEO3hnbVTjMAeyNrCoshcrvmZa1ho7dU4F2NiVCiQv+mbLQ0DEfSQ5d X-Developer-Key: i=kasong@tencent.com; a=ed25519; pk=kCdoBuwrYph+KrkJnrr7Sm1pwwhGDdZKcKrqiK8Y1mI= X-Endpoint-Received: by B4 Relay for kasong@tencent.com/kasong-sign-tencent with auth_id=562 X-Original-From: Kairui Song Reply-To: kasong@tencent.com From: Kairui Song Add a helper that resolves a stable lruvec for a folio under RCU without taking the lruvec lock. It takes a folio directly so the lruvec lookup happens inside the RCU read-side critical section, which a lruvec-based interface cannot guarantee. No functional change. Tested-by: zhaozhengzhuo Signed-off-by: Kairui Song --- include/linux/memcontrol.h | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 74110a324f9e..829ab776ab44 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1535,6 +1535,45 @@ static inline void lruvec_lock_irq(struct lruvec *lruvec) spin_lock_irq(&lruvec->lru_lock); } +/** + * folio_lruvec_live_get - get a live lruvec for a folio under RCU + * @folio: the folio + * + * Computes @folio's lruvec and walks up to the nearest live ancestor + * if the folio's memcg is dying. Paired with folio_lruvec_live_put(). + * The result may be stale: RCU keeps it alive but does not pin @folio + * to it. That is fine as the counters are fixed up on reparenting. + * + * Return: the live lruvec, with rcu_read_lock held. + */ +static inline struct lruvec *folio_lruvec_live_get(struct folio *folio) +{ +#ifdef CONFIG_MEMCG + struct lruvec *lruvec; + struct pglist_data *pgdat; + struct mem_cgroup *memcg; + + rcu_read_lock(); + lruvec = folio_lruvec(folio); + pgdat = lruvec_pgdat(lruvec); + memcg = lruvec_memcg(lruvec); + while (unlikely(memcg && css_is_dying(&memcg->css))) { + memcg = parent_mem_cgroup(memcg); + lruvec = mem_cgroup_lruvec(memcg, pgdat); + } + return lruvec; +#else + return folio_lruvec(folio); +#endif +} + +static inline void folio_lruvec_live_put(struct lruvec *lruvec) +{ +#ifdef CONFIG_MEMCG + rcu_read_unlock(); +#endif +} + static inline struct lruvec *lruvec_live_lock_irq(struct lruvec *lruvec) { #ifdef CONFIG_MEMCG -- 2.56.0