From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 17077D64085 for ; Wed, 17 Dec 2025 07:31:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7C4246B00A7; Wed, 17 Dec 2025 02:31:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7ACFF6B00A9; Wed, 17 Dec 2025 02:31:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6AE796B00AA; Wed, 17 Dec 2025 02:31:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 571716B00A7 for ; Wed, 17 Dec 2025 02:31:46 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 2F939140929 for ; Wed, 17 Dec 2025 07:31:46 +0000 (UTC) X-FDA: 84228143412.22.1222485 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) by imf01.hostedemail.com (Postfix) with ESMTP id 7575040013 for ; Wed, 17 Dec 2025 07:31:44 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rcM1irid; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf01.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.182 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765956704; a=rsa-sha256; cv=none; b=DFjl2O3pWP2ZE/QcM1Rb/AJDikaLPIQ39J8khDv9N/+kWgy4QL5fzzpgX+KWLOzn6qiQhG G2f7RWW90dwDIyfNLyXnHDAiLC+EQ/7SnfIoJYNpcdFVfLI0fv3cKUrFttOZBxN6DlKipt vBIbe+fnC//BjdKI7DddSyU8YJOpm3c= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rcM1irid; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf01.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.182 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1765956704; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=O/RC2JaZfQWnRGhHEhR7EU7DG2VrpSmCFoSBZ0fAAxk=; b=2all9+Y9J9rahgdLMQOpMNI0Lfl49JYQa/Fo+uvwmb3Y0nnEzHWD0GtQKTEFzQhx5L1TUA PMnqnHL/i070L1p32k820NN21dGafIIxejwGxeNPrOKYySVwOGr2wAA+QUIVibhvvAhpSf gzd/EU6/B5csMYu2/URHFcbn1tkmvjQ= 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=1765956697; 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=O/RC2JaZfQWnRGhHEhR7EU7DG2VrpSmCFoSBZ0fAAxk=; b=rcM1irid7iZhLEiyC31dWf7GEZg2x6QnaCq8514+s+TRHJjJRBt5XX0VjwPoXWf4b870kM gF5CmOgkGe+CAHQ+l47v+XRNjSHJHKl4eleD+t4cE2jzU/bol8kuSG/q/eFSE/KS5KSEvx XfQohA5II8VscYDtO1EgTJmoLnFVmII= From: Qi Zheng To: hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, harry.yoo@oracle.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, chenridong@huaweicloud.com, mkoutny@suse.com, akpm@linux-foundation.org, hamzamahfooz@linux.microsoft.com, apais@linux.microsoft.com, lance.yang@linux.dev Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v2 14/28] mm: mglru: prevent memory cgroup release in mglru Date: Wed, 17 Dec 2025 15:27:38 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7575040013 X-Stat-Signature: a8jnf577yt1oifwbc3n8374ydwuuazf7 X-HE-Tag: 1765956704-678893 X-HE-Meta: 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 q+hNZali KbOl9b9bd/MIJ6ZZHCFMn2rrDPxuh8oVHh9E+sx8K7MK6iE64+QpWl/jrJjO2goZWCuqw/PZjjKDgDSsWTOawPPjqxCmpuXk/0YAjvyxDlMrWqfrNAGQSfoYrGYlQ/NUewpYrL3GsR62+3fbQ2Cdj8qOJNqz7o4LhrEDy3REX5V/c3YB4znL/9YQ5nkE/FKnNuGWPfzEuhgHXSV13yuZABTXm4w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Muchun Song In the near future, a folio will no longer pin its corresponding memory cgroup. To ensure safety, it will only be appropriate to hold the rcu read lock or acquire a reference to the memory cgroup returned by folio_memcg(), thereby preventing it from being released. In the current patch, the rcu read lock is employed to safeguard against the release of the memory cgroup in mglru. This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Signed-off-by: Qi Zheng --- mm/vmscan.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 354b19f7365d4..814498a2c1bd6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3444,8 +3444,10 @@ static struct folio *get_pfn_folio(unsigned long pfn, struct mem_cgroup *memcg, if (folio_nid(folio) != pgdat->node_id) return NULL; + rcu_read_lock(); if (folio_memcg(folio) != memcg) - return NULL; + folio = NULL; + rcu_read_unlock(); return folio; } @@ -4202,12 +4204,12 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) unsigned long addr = pvmw->address; struct vm_area_struct *vma = pvmw->vma; struct folio *folio = pfn_folio(pvmw->pfn); - struct mem_cgroup *memcg = folio_memcg(folio); + struct mem_cgroup *memcg; struct pglist_data *pgdat = folio_pgdat(folio); - struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat); - struct lru_gen_mm_state *mm_state = get_mm_state(lruvec); - DEFINE_MAX_SEQ(lruvec); - int gen = lru_gen_from_seq(max_seq); + struct lruvec *lruvec; + struct lru_gen_mm_state *mm_state; + unsigned long max_seq; + int gen; lockdep_assert_held(pvmw->ptl); VM_WARN_ON_ONCE_FOLIO(folio_test_lru(folio), folio); @@ -4242,6 +4244,13 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) } } + rcu_read_lock(); + memcg = folio_memcg(folio); + lruvec = mem_cgroup_lruvec(memcg, pgdat); + max_seq = READ_ONCE((lruvec)->lrugen.max_seq); + gen = lru_gen_from_seq(max_seq); + mm_state = get_mm_state(lruvec); + arch_enter_lazy_mmu_mode(); pte -= (addr - start) / PAGE_SIZE; @@ -4282,6 +4291,8 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) if (mm_state && suitable_to_scan(i, young)) update_bloom_filter(mm_state, max_seq, pvmw->pmd); + rcu_read_unlock(); + return true; } -- 2.20.1