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 57683D29FF1 for ; Wed, 14 Jan 2026 11:34:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C0DB86B00AD; Wed, 14 Jan 2026 06:34:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BEC306B00AF; Wed, 14 Jan 2026 06:34:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B21C16B00B0; Wed, 14 Jan 2026 06:34:47 -0500 (EST) 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 9F62C6B00AD for ; Wed, 14 Jan 2026 06:34:47 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6F69A8BB3A for ; Wed, 14 Jan 2026 11:34:47 +0000 (UTC) X-FDA: 84330362214.16.1D24C81 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) by imf11.hostedemail.com (Postfix) with ESMTP id BB1DF4000A for ; Wed, 14 Jan 2026 11:34:45 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=EGUnEaVZ; spf=pass (imf11.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=1768390485; 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=QCopSypjYe82peR7lY73wGmY04x1cNXQciUkTwdGqJY=; b=j6Mg+xARyT5m3YrkXJaGDbcTPbb7UyEk/DV7/UGW0XUYvl4TME37j+bLMWfwTM5cW2j9Nh HZtsq76EAdYpWuS9QKK8JxQy80tGObNq9QmRu/9K3DfHkfNC9ZD+JkRZ9H2UxOS75r83vk P04Jk2BChovChI2UADCajjdS0v2Oc3E= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=EGUnEaVZ; spf=pass (imf11.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=1768390485; a=rsa-sha256; cv=none; b=oqNjTw9KiChmTKVGYuyAg940KKSiHJDhVVj81HzGJexYlTQdXOXKZldxcf6ywJ6vhE3SLQ RQu0pVJqs9Bmm8WyEAqaCEvU6iBinypmN3x1YxKjf06mkxqK0EDZYOHQg0upFslU0zfxRE BlmsmDCkZXCu+CvLXuhRnkp+kDy8eA4= 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=1768390482; 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=QCopSypjYe82peR7lY73wGmY04x1cNXQciUkTwdGqJY=; b=EGUnEaVZY5ecLmqLWynQvM1889GDtdaiRYfuzcFinAOWYaXuSUoNw9++8ch5q+nFpsNkwv TZvM57lPQIOOMPKpVkSNKlF6qt4KGBSImERx5HgN6Ir16WQscR1fE94QGhIY5LdBI0Qb30 0xvcPfgqOk4+Ey/3r42TnZgFMnvgdh8= 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, Qi Zheng Subject: [PATCH v3 17/30] mm: thp: prevent memory cgroup release in folio_split_queue_lock{_irqsave}() Date: Wed, 14 Jan 2026 19:32:44 +0800 Message-ID: <061b1110696ba51e454ad0f7549603ec92cdb5ea.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: 5ya97ij993hmdfb1mbjjfre95xt86hjq X-Rspamd-Queue-Id: BB1DF4000A X-Rspamd-Server: rspam04 X-HE-Tag: 1768390485-341277 X-HE-Meta: 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 9pjSo5jc +SLeOFCwi1+mcjHKFMKWkwQezZTsaHyQz1NBi2DXXiiT51h4zirT0gvVro3P7Ap7k6USwuSD3Xd36ik4IjW2k/+aJ4HN81iKPxlP39jZvyk1mcY4kY3XGInq7UA5B/Bt3VPWM+e/VhrrFIRcPKHFpCut1texGGylg1acF4pYwQ6Bbh3e5cB+NZ1nC6DLTatA5HEpCv1HWnYnp/EyyDTdkhF85CLCtAREHIi2ruwrI1PZlbBfPe8XOeDuobwJvZSyb1n7sUDvz+vaFlk2sN8Mdl9YZuNIsSQkOZM7Lwt8xN249N2GTewv0gl9mOT/5bOLTYsuk0HdiPJhCCRG8wrAxF6wLrAgo2OvaABZPFB/PzWlPIcsOaJPaIWKyAQ== 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: Qi Zheng 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 folio_split_queue_lock{_irqsave}(). Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo Acked-by: Johannes Weiner Acked-by: Shakeel Butt Acked-by: David Hildenbrand (Red Hat) --- mm/huge_memory.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 99515838faa51..eb611239c1a74 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1154,13 +1154,29 @@ split_queue_lock_irqsave(int nid, struct mem_cgroup *memcg, unsigned long *flags static struct deferred_split *folio_split_queue_lock(struct folio *folio) { - return split_queue_lock(folio_nid(folio), folio_memcg(folio)); + struct deferred_split *queue; + + rcu_read_lock(); + queue = split_queue_lock(folio_nid(folio), folio_memcg(folio)); + /* + * The memcg destruction path is acquiring the split queue lock for + * reparenting. Once you have it locked, it's safe to drop the rcu lock. + */ + rcu_read_unlock(); + + return queue; } static struct deferred_split * folio_split_queue_lock_irqsave(struct folio *folio, unsigned long *flags) { - return split_queue_lock_irqsave(folio_nid(folio), folio_memcg(folio), flags); + struct deferred_split *queue; + + rcu_read_lock(); + queue = split_queue_lock_irqsave(folio_nid(folio), folio_memcg(folio), flags); + rcu_read_unlock(); + + return queue; } static inline void split_queue_unlock(struct deferred_split *queue) -- 2.20.1