linux-kernel - [PATCH RFC 21/28] mm: zswap: prevent lruvec release in zswap_folio

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: <20250415024532.26632-22-songmuchun@bytedance.com>
Date: Tue, 15 Apr 2025 10:45:25 +0800
From: Muchun Song <songmuchun@...edance.com>
To: hannes@...xchg.org,
	mhocko@...nel.org,
	roman.gushchin@...ux.dev,
	shakeel.butt@...ux.dev,
	muchun.song@...ux.dev,
	akpm@...ux-foundation.org,
	david@...morbit.com,
	zhengqi.arch@...edance.com,
	yosry.ahmed@...ux.dev,
	nphamcs@...il.com,
	chengming.zhou@...ux.dev
Cc: linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org,
	linux-mm@...ck.org,
	hamzamahfooz@...ux.microsoft.com,
	apais@...ux.microsoft.com,
	Muchun Song <songmuchun@...edance.com>
Subject: [PATCH RFC 21/28] mm: zswap: prevent lruvec release in zswap_folio_swapin()

In the near future, a folio will no longer pin its corresponding
memory cgroup. So an lruvec returned by folio_lruvec() could be
released without the rcu read lock or a reference to its memory
cgroup.

In the current patch, the rcu read lock is employed to safeguard
against the release of the lruvec in zswap_folio_swapin().

This serves as a preparatory measure for the reparenting of the
LRU pages.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/zswap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/zswap.c b/mm/zswap.c
index 204fb59da33c..4a41c2371f3d 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -752,8 +752,10 @@ void zswap_folio_swapin(struct folio *folio)
 	struct lruvec *lruvec;
 
 	if (folio) {
+		rcu_read_lock();
 		lruvec = folio_lruvec(folio);
 		atomic_long_inc(&lruvec->zswap_lruvec_state.nr_disk_swapins);
+		rcu_read_unlock();
 	}
 }
 
-- 
2.20.1