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 15048D29FF1 for ; Wed, 14 Jan 2026 11:34:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7E7766B00A3; Wed, 14 Jan 2026 06:34:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7CF126B00A4; Wed, 14 Jan 2026 06:34:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6D2146B00A5; Wed, 14 Jan 2026 06:34:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 5C02C6B00A3 for ; Wed, 14 Jan 2026 06:34:18 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 21E971BB6F for ; Wed, 14 Jan 2026 11:34:18 +0000 (UTC) X-FDA: 84330360996.12.05464CA Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) by imf29.hostedemail.com (Postfix) with ESMTP id 775E412000B for ; Wed, 14 Jan 2026 11:34:16 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=KmDvj3Gd; spf=pass (imf29.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1768390456; 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=2JlAZQzRN5bDs3qiAHWl4rWTV4PeQocYNGSREH21AX0=; b=h2EDe1JO9DXVifvwvbh8/HAa3VbphSP1wcnCiLd01f0NoV2eRPTTJ3SSQ2UCKVrPmybl8E 4oomxtk4lXTnNv1kODmA7nRxDf/2rfUmcfmfRi7zLnmhpGsCoQTAs8EcgyBynZmg7u/5qJ yUN+4xLbh79y6BLXBNgib1e4GTbZn/A= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=KmDvj3Gd; spf=pass (imf29.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.174 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=1768390456; a=rsa-sha256; cv=none; b=RkRj0FPRgRCMXJaOGpVVF2zTR5lV34p/Er0Kvu6YOyK5iss/xE/ucS8mIZ67AKON3J3ncU R9RFAdaAEV9bQO+h/e1+wCS85p0Jdztu2s7s0OxJ1w1qCsSul+TAYUEZBgA0upyzAvFaSg 1mNqrJajEaZj8ZZ1izRMOHCysGrf15E= 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=1768390454; 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=2JlAZQzRN5bDs3qiAHWl4rWTV4PeQocYNGSREH21AX0=; b=KmDvj3GdhPZVoqp8eC9pasVuk9TdYg3eQpn308+RW0JPRapnnho1n3PcJ7C09UbRdZ6cl+ dgs8UTs8ZxmghI7oxFWkqBtV0wFvTOg52Yt6jTxq0JVS1pyoTU/xx5hxyDJwFtMsxolMyf IVGl59Th2CkCBHW5Taqq03chB5G5zJg= 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 Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng Subject: [PATCH v3 14/30] mm: mglru: prevent memory cgroup release in mglru Date: Wed, 14 Jan 2026 19:32:41 +0800 Message-ID: <2a42effe148a31d308075f9fe72bd76d126b96b8.1768389889.git.zhengqi.arch@bytedance.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: rk1dyeiwrcchcmewcrjc5hentub3h6bs X-Rspamd-Queue-Id: 775E412000B X-Rspamd-Server: rspam04 X-HE-Tag: 1768390456-864892 X-HE-Meta: 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 LSkb5ajB Rtdl178hZLHfFnuylvDHfJG0rIf6UQJ77mgYakQgHMEO43uzrQyYUXRQWTGA1GR1nZDw4G50+Mo5zqYHioBTtyHWk5FnQw69HE1IESarVLSnkrv+5r4lWbxJPl2/EbOewalva80WviM8QCDEOxHeUyC1i0Ul4+bY41Mg2rGV912nr4f/NyULfUWahL8iZhBUpZy8hcrEjVuOq88HaX/TEeLgqqA== 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 | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 20cd54c5cbc79..f206d4dac9e77 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3481,8 +3481,10 @@ 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; } @@ -4239,12 +4241,12 @@ 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); @@ -4279,6 +4281,12 @@ 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; @@ -4319,6 +4327,8 @@ 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