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 D9A62EFD204 for ; Wed, 25 Feb 2026 07:53:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 492FF6B009B; Wed, 25 Feb 2026 02:53:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 44A8A6B009F; Wed, 25 Feb 2026 02:53:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 34D136B00AA; Wed, 25 Feb 2026 02:53:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 22A4F6B009B for ; Wed, 25 Feb 2026 02:53:52 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id D456C1C574 for ; Wed, 25 Feb 2026 07:53:51 +0000 (UTC) X-FDA: 84482215062.29.4493DB1 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) by imf14.hostedemail.com (Postfix) with ESMTP id EB5C6100004 for ; Wed, 25 Feb 2026 07:53:49 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bSzXDBjO; spf=pass (imf14.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.173 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772006030; a=rsa-sha256; cv=none; b=4ubIJ29EOm73AUvrIUyfoaEoofTP2SyVh3u+wiak/Jz92VXneydZ0T7uOetZqHsFNXeJos 2r1yS6HHYl5/NAA0AMZKXtkKOIghjR4iTbq6UUweWc1l3fOf47wCZqFdVkNNKseQ8qFtGV 4nPGel0L+QVD2AAeYvTf9tBTp3P6W+4= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bSzXDBjO; spf=pass (imf14.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.173 as permitted sender) smtp.mailfrom=qi.zheng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772006030; 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=50It2KWkplJCk5rfNOAinOMdF3qOxn822zHuSg5yVbw=; b=Inz7qi57xWhkRrv/jk/khQ/utjD1Aknx6Rj4Rlud49hJuZOTZc/jXP0ft5AO++5ZjLh7k4 +mE8/Jb6Lc1C+N1oobvHNdF5meGoxkfM94Xl3qN3PCaVx7yxNnU3ZJ3Ja3KR/ARp8hOxzr qJ5VyoS/gfii+EMwWT3mnkQ8aYY5Yp4= 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=1772006028; 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=50It2KWkplJCk5rfNOAinOMdF3qOxn822zHuSg5yVbw=; b=bSzXDBjOYsTbN1IS1mijNvpCfRCrk1olS9/qHw+FBryEX++s7UM8isB9xcHpwhF6VwDQEe jXnMIKJEWAlzGLCQmSi0FoAbLf8IfIjxvB/op0aIFS4jDgEBElB04rtPXsRUCqBsatfXL6 VW8kXnoCPfl0Fjd9LhrDshacXB7VDZk= 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, usamaarif642@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v5 14/32] mm: mglru: prevent memory cgroup release in mglru Date: Wed, 25 Feb 2026 15:52:57 +0800 Message-ID: <9d887662a9d39c425742dd8468e3123316bccfe3.1772005110.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: EB5C6100004 X-Stat-Signature: a59a9f5q41jtqypdfaheggou4gz5dszd X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1772006029-790189 X-HE-Meta: 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 7zK3pQBX eBda92JXb4voLyXA1GzCjw8edRPcoz8fVLfwLEfS7E6VJU6KoWOQX81sIb2/jIJZS+npSK0Oh1SDaXdfKPVVAEuEwT3bptBBx0iQOmAwtIVKqbcbFacaeVliJNG7yuRCEaWGcjb+ye2h1sZBD6ljkujx83YJEHjHHZq3QXPatmRTHsbyRH/Im5TYzcxMsBx0vxYLp8Usxwy3qSBg= 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 61303ec85d587..024ff870b1a03 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3443,8 +3443,10 @@ 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 +4244,12 @@ 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; @@ -4282,6 +4290,8 @@ 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