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 AB806CCD1BF for ; Tue, 28 Oct 2025 14:03:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 150FD80153; Tue, 28 Oct 2025 10:03:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0DB368013F; Tue, 28 Oct 2025 10:03:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EE4D580153; Tue, 28 Oct 2025 10:02:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id D83118013F for ; Tue, 28 Oct 2025 10:02:59 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id A349412A865 for ; Tue, 28 Oct 2025 14:02:59 +0000 (UTC) X-FDA: 84047689278.01.DDFF9DF Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) by imf21.hostedemail.com (Postfix) with ESMTP id ECA9C1C000F for ; Tue, 28 Oct 2025 14:02:57 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=q4KXYujY; spf=pass (imf21.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.188 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=1761660178; 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=KwZ644xbYvlNcagDZjQ0mKRDmPXR0vZ+/IMJ8ruGmik=; b=OXUs2i9bLEIm3eQRbrmsbJnumuvjsZ5yEPLWwy6q1y74llsG+ts6BeP1GhU2YMoXkCSHSo V3Rvfsekebiv8hvvCjYFF/28TjBqPjJSY0vIhAm7xVEe+vUQaLf8LJEj6PMbcpdc8zhKmx Zk+bHze0TXa3yEDCSkx8toyFRXqezgk= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=q4KXYujY; spf=pass (imf21.hostedemail.com: domain of qi.zheng@linux.dev designates 91.218.175.188 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=1761660178; a=rsa-sha256; cv=none; b=pk5muauuXNumBs7gSBOYBCXu5kkAo1c+zcStitcAhDwDlwCTFf6mXCexOKzxTOyaPYDqDZ cphaNFTl13zWyfm8JxjkOBeRvp/yZm/oOHNkTrjw7mcJ6e6uW5Ci3UsKXw2aqP9CDV7bIe zQkF5LoSZyoKX0Svg2qU+TK4LmPYzEI= 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=1761660176; 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=KwZ644xbYvlNcagDZjQ0mKRDmPXR0vZ+/IMJ8ruGmik=; b=q4KXYujYUCNGMd6/2GfYLrwuY6WKfDyyGjAFmIfFVpIINUQT+TYRszwkW0sd/3PfetejZz qFDU7mIuGhZ3R8LP+L8tH0OPOfJMdxCIBW7lZeAT7MGVMa+sgKyH9un9PUQmNiCyyFDaba dJb66qMsLrpMqVBKRqibHSucfgUHoak= 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 07/26] mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio() Date: Tue, 28 Oct 2025 21:58:20 +0800 Message-ID: <9eca65dec044d4352bee84511fb58960a1402ddf.1761658310.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: ECA9C1C000F X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: ffzi8t96ntpsczxytri5hewof1781eye X-HE-Tag: 1761660177-436304 X-HE-Meta: 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 jJLElEuO 9mQb6ytxY4TFLh6em2LKQueENgX3kAbOsjas3oUG7tWSh+b9QR2KBiwVRE8REBc8HpF1lPTnKVfl20tgdefsYXz0D68thdHmfn49T8uiQXHhxPxay2NtQZlGK3O/k9dcUet9tjqqSuNbqcAS7Lsdbvuhe94wqPaZZraSsSK6LFk/NiLX27/d+BieClhhpuFSd3qWhzx2x/L4OaoKXA6JQObDq0cMOfrCMWg7iIz37IKTCXI3HOx8oJ+E1TJ+n5sF+7yFBAlYfbZUV0lw= 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 get_mem_cgroup_from_folio(). This serves as a preparatory measure for the reparenting of the LRU pages. Signed-off-by: Muchun Song Signed-off-by: Qi Zheng --- mm/memcontrol.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d484b632c790f..1da3ad77054d3 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -973,14 +973,19 @@ struct mem_cgroup *get_mem_cgroup_from_current(void) */ struct mem_cgroup *get_mem_cgroup_from_folio(struct folio *folio) { - struct mem_cgroup *memcg = folio_memcg(folio); + struct mem_cgroup *memcg; if (mem_cgroup_disabled()) return NULL; + if (!folio_memcg_charged(folio)) + return root_mem_cgroup; + rcu_read_lock(); - if (!memcg || WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg = root_mem_cgroup; +retry: + memcg = folio_memcg(folio); + if (unlikely(!css_tryget(&memcg->css))) + goto retry; rcu_read_unlock(); return memcg; } -- 2.20.1