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 8ABF8CCF9E0 for ; Tue, 28 Oct 2025 14:03:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DFDCD80159; Tue, 28 Oct 2025 10:03:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DAD9F8013F; Tue, 28 Oct 2025 10:03:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C9C5680159; Tue, 28 Oct 2025 10:03:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id B15218013F for ; Tue, 28 Oct 2025 10:03:42 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 6F6E0140472 for ; Tue, 28 Oct 2025 14:03:42 +0000 (UTC) X-FDA: 84047691084.04.0B2951D Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf12.hostedemail.com (Postfix) with ESMTP id D30F440009 for ; Tue, 28 Oct 2025 14:03:40 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=fhoHKTrq; spf=pass (imf12.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 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=1761660221; 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=wkLnu/O9q4xdyqjaFOUvki0UTYleR0McbTd1ETEhnKE=; b=nZ3VFDIad7s9p5lGgSSFpo3Hyhw/47mEg6e9IT/cQIW4Oj4u9D5Bcc7Sof7knpukcwmtwd hPgO0bOcKfc+V0dAA3LtGKYAAb+ZSTZZQNFaYSuZrlIqCuf2fzFu7YkYlaR5BjSjeay0tz 1jLO4cw9+bCuFGyCYycDplmkvbkYcc8= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=fhoHKTrq; spf=pass (imf12.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.184 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=1761660221; a=rsa-sha256; cv=none; b=O8vMb+zFhz0lFEQu7GXteANWfVd6XmL1X+jed4bHFHcsNLieb7vo0cYwv14ax5SHPLv9Hh tNyE7HrP+YR1+GTy2/BmAm+5xVMdhIOvqepkuh8PmQIgtw6P4w5s5vbOKkGjsPycR44ACk 6Sel3NQPoPYdrA4N51aUGEwlncgVzm0= 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=1761660219; 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=wkLnu/O9q4xdyqjaFOUvki0UTYleR0McbTd1ETEhnKE=; b=fhoHKTrqeVk6EZTuFAS26dH7KFQqARavNeR76iE73qBaEIWQbclTIzwrgj8JSL8qtfhWPz Prin+M4U0nQHEyZAfPOwRr6LzXUBd1RKMclEfqJMc+oKdYk9NayqXqvzChMmpi6ZmtuPOL IHh2SSrRo7IPh5r1+4Fh+biiYMfo3io= 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@redhat.com, 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, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v1 13/26] mm: mglru: prevent memory cgroup release in mglru Date: Tue, 28 Oct 2025 21:58:26 +0800 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 6zfhuaugpmxfga6jgfo77ft9emhx5w5k X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D30F440009 X-HE-Tag: 1761660220-884425 X-HE-Meta: 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 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 660cd40cfddd4..676e6270e5b45 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3445,8 +3445,10 @@ 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; } @@ -4203,12 +4205,12 @@ 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); @@ -4243,6 +4245,13 @@ 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; @@ -4279,6 +4288,8 @@ bool lru_gen_look_around(struct page_vma_mapped_walk *pvmw) arch_leave_lazy_mmu_mode(); + rcu_read_unlock(); + /* feedback from rmap walkers to page table walkers */ if (mm_state && suitable_to_scan(i, young)) update_bloom_filter(mm_state, max_seq, pvmw->pmd); -- 2.20.1