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 3F60BE91297 for ; Thu, 5 Feb 2026 09:03:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A7B6D6B00A6; Thu, 5 Feb 2026 04:03:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A461A6B00AA; Thu, 5 Feb 2026 04:03:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 965C96B00AB; Thu, 5 Feb 2026 04:03:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 84AA76B00A6 for ; Thu, 5 Feb 2026 04:03:06 -0500 (EST) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 45086B97FC for ; Thu, 5 Feb 2026 09:03:06 +0000 (UTC) X-FDA: 84409813572.20.07ABE48 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) by imf15.hostedemail.com (Postfix) with ESMTP id 88EE7A0009 for ; Thu, 5 Feb 2026 09:03:04 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tSjJRYH8; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.187 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1770282184; a=rsa-sha256; cv=none; b=nOzTwwb8I3wXUq9oRMx+7Q3YfwN75mGa2zn5gZVmBbWopJSkjc8ogC43tH9tGT0cYVfC7L DRnLWEnBp5s/mrSsofSsXRB0CTqdrx+NGcyDkoFORCPuhbZHeK3O/nGWXJfXFZPedo+msN lfbKF7Gt+ovaf2xAgVFMNq6VHRxB0n8= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=tSjJRYH8; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf15.hostedemail.com: domain of qi.zheng@linux.dev designates 95.215.58.187 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=1770282184; 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=J628NvVCX1ADaXWvBnIXUo0oeiXoWRHWWgu66rJ1mAA=; b=bBS8/eyMmSZ6+uvKGTxlkxksjOXx82VG8kiYEca4uxY/onto/O5ohhC6G8pN9WYQkSA6zr MStnsAK2MOSqCkiJmd1RDDHCnNSAjsA0AQo+nB93bWJSvTqDwnEnK1WHMjKPZSBsNiTYZ0 KRt2cvOHMueoYYGTWzGOFCFZkXIO7gM= 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=1770282183; 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=J628NvVCX1ADaXWvBnIXUo0oeiXoWRHWWgu66rJ1mAA=; b=tSjJRYH8XwIGi6IfN+owvz08VcSRLJD8CJusIhfEQb46DUmYBA6mXAfRJZYUHi1U+WcuxB 4PzZmP1kKLqXEhO6FoRyERJiO/0xafqYhZZsNrAlMVGB+cP1p3OowGntAo4fYwauLKNh4A ZaubGhliPHZZRq9Bi5EVPYj/Ci3rvB4= 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, yosry.ahmed@linux.dev, 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, bhe@redhat.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v4 14/31] mm: mglru: prevent memory cgroup release in mglru Date: Thu, 5 Feb 2026 17:01:33 +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: rspam06 X-Rspamd-Queue-Id: 88EE7A0009 X-Stat-Signature: xyyfwo8bscpcdoxjt6ertt1fo5mf3ph8 X-HE-Tag: 1770282184-843692 X-HE-Meta: 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 426qSp/k +3Xwl5UXXfpGjksdtiVVoyFcz/+oBrXYPeN+3ckgwlUfw9QVLNHm5c1mq8LELMvwQcYLTqF1irwvnLy3Gjrp58lGp+kkx9PMYINM3MOJLfFzRDul4Hcl5EB7RHIlU4O71FJM0WDcM9IWX9mzw8+bQcVJdSiFfJqXwO/YmVNBLScLTHv844A9vtoRcRP4ykisHay0l6pCPOmDv/BE= 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 Acked-by: Shakeel Butt Reviewed-by: Harry Yoo --- mm/vmscan.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 8039df1c9fca5..6a7eacd39bc5f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3450,8 +3450,10 @@ 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; } @@ -4208,12 +4210,12 @@ 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); @@ -4248,6 +4250,12 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) } } + memcg = get_mem_cgroup_from_folio(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); + lazy_mmu_mode_enable(); pte -= (addr - start) / PAGE_SIZE; @@ -4288,6 +4296,8 @@ 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); + mem_cgroup_put(memcg); + return true; } -- 2.20.1