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 73EA2F30950 for ; Thu, 5 Mar 2026 11:56:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DDD356B00AD; Thu, 5 Mar 2026 06:56:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DA4946B00AF; Thu, 5 Mar 2026 06:56:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CD5646B00B0; Thu, 5 Mar 2026 06:56:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B9A646B00AD for ; Thu, 5 Mar 2026 06:56:33 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7E1251CC43 for ; Thu, 5 Mar 2026 11:56:33 +0000 (UTC) X-FDA: 84511857066.22.72B2AFE Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) by imf30.hostedemail.com (Postfix) with ESMTP id CB5158000D for ; Thu, 5 Mar 2026 11:56:31 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=aYY6BFEh; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.179 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=1772711792; 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=1RBj3rxAe01Y1cDPUXngmM+m+CkzsKHsdgS6kXmPwZbpTsPmWthoa8fvhwt0GRFp2jDcO3 mCT5Vm7VatlVqs8It8ecrexosVP9mNtC2LNZ9bB6JrBpJsiUGx0Oss9Ru/UgaAw7aQhQnJ FKbhUpj7srEH2NG0hcVe+tv6y2duIOM= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=aYY6BFEh; spf=pass (imf30.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.179 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=1772711792; a=rsa-sha256; cv=none; b=NFe9l1SyNWUFzTLruBJQctOq0Urv+D7e5MmZ3Nd1tuH4HuX5vmfkDqSU5BYYUWmv36hVkV ObsonuTXnWQYW1a9XcI7kg2hUoTKmVt6GFd40WcsQhG33T8Amtgr5ROFkt9UH1Icp2kbGN O5/4CquUi8bF3gHjnz6B+n1Z+ZBNwA0= 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=1772711789; 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=aYY6BFEhf3mRI3VEazB541/h+Ze1kRL1T3Rkx2QrL6z4PUiW/zGnHy3PoFZBmvGLsO0m3n n1ulPJkbmUdk9NdpCNGrTnTk69ATRWXhf8K/4eKeCiyoxOVjm91Y6ghwuFwnSmjwthd/Iy kOTAGa1xFjCZIWPSMsCLoL0zwIKrHWI= 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 v6 14/33] mm: mglru: prevent memory cgroup release in mglru Date: Thu, 5 Mar 2026 19:52:32 +0800 Message-ID: <9d887662a9d39c425742dd8468e3123316bccfe3.1772711148.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: CB5158000D X-Rspamd-Server: rspam07 X-Stat-Signature: ktcigrwqk3g3h9hrc5t9w6m5xtx6bstg X-Rspam-User: X-HE-Tag: 1772711791-531230 X-HE-Meta: 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 NiYqnpZU 2yNnyF7l5A9AWaem+W0ZqsJq9RjqNGWC8FpiLVbxiLY7NxGLJRbbzkWQHEIbvp4euA8tmHe6zCfIRL+qIqAB+WI2NACJffrXr1kcdysFfXudfkNqHM2O6jKgXgrMlUTbVUUot8bwlq711QUNOmeH7OlURd8XLojvu0+dfjbMPDkXXKfAwED/Wjc1kHhUctSJgvhP+Wiv+cseXfz4= 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