linux-kernel - [PATCH v1 16/26] mm: thp: prevent memory cgroup release in folio_split_queue_lock{

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ae89721afa0a21376eeb3386fa60f7426c746cd7.1761658310.git.zhengqi.arch@bytedance.com>
Date: Tue, 28 Oct 2025 21:58:29 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: hannes@...xchg.org,
	hughd@...gle.com,
	mhocko@...e.com,
	roman.gushchin@...ux.dev,
	shakeel.butt@...ux.dev,
	muchun.song@...ux.dev,
	david@...hat.com,
	lorenzo.stoakes@...cle.com,
	ziy@...dia.com,
	harry.yoo@...cle.com,
	imran.f.khan@...cle.com,
	kamalesh.babulal@...cle.com,
	axelrasmussen@...gle.com,
	yuanchu@...gle.com,
	weixugc@...gle.com,
	akpm@...ux-foundation.org
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v1 16/26] mm: thp: prevent memory cgroup release in folio_split_queue_lock{_irqsave}()

From: Qi Zheng <zhengqi.arch@...edance.com>

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 <zhengqi.arch@...edance.com>
---
 mm/huge_memory.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9d3594df6eedf..067259a9e0809 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1153,13 +1153,25 @@ 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));
+	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