The patch titled Subject: mm-list_lru-fix-uaf-for-memory-cgroup-v2 has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-list_lru-fix-uaf-for-memory-cgroup-v2.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Muchun Song songmuchun@bytedance.com Subject: mm-list_lru-fix-uaf-for-memory-cgroup-v2 Date: Thu, 1 Aug 2024 10:46:03 +0800

only grab rcu lock when necessary, per Vlastimil

Link: https://lkml.kernel.org/r/20240801024603.1865-1-songmuchun@bytedance.com Fixes: 0a97c01cd20b ("list_lru: allow explicit memcg and NUMA node selection") Signed-off-by: Muchun Song songmuchun@bytedance.com Acked-by: Shakeel Butt shakeel.butt@linux.dev Cc: stable@vger.kernel.org Cc: Johannes Weiner hannes@cmpxchg.org Cc: Nhat Pham nphamcs@gmail.com Cc: Vlastimil Babka vbabka@suse.cz Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/list_lru.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-)

--- a/mm/list_lru.c~mm-list_lru-fix-uaf-for-memory-cgroup-v2 +++ a/mm/list_lru.c @@ -112,12 +112,14 @@ bool list_lru_add_obj(struct list_lru *l { bool ret; int nid = page_to_nid(virt_to_page(item)); - struct mem_cgroup *memcg;

- rcu_read_lock(); - memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL; - ret = list_lru_add(lru, item, nid, memcg); - rcu_read_unlock(); + if (list_lru_memcg_aware(lru)) { + rcu_read_lock(); + ret = list_lru_add(lru, item, nid, mem_cgroup_from_slab_obj(item)); + rcu_read_unlock(); + } else { + ret = list_lru_add(lru, item, nid, NULL); + }

return ret; } @@ -148,12 +150,14 @@ bool list_lru_del_obj(struct list_lru *l { bool ret; int nid = page_to_nid(virt_to_page(item)); - struct mem_cgroup *memcg;

- rcu_read_lock(); - memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL; - ret = list_lru_del(lru, item, nid, memcg); - rcu_read_unlock(); + if (list_lru_memcg_aware(lru)) { + rcu_read_lock(); + ret = list_lru_del(lru, item, nid, mem_cgroup_from_slab_obj(item)); + rcu_read_unlock(); + } else { + ret = list_lru_del(lru, item, nid, NULL); + }

return ret; } _

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-list_lru-fix-uaf-for-memory-cgroup.patch mm-list_lru-fix-uaf-for-memory-cgroup-v2.patch mm-kmem-remove-mem_cgroup_from_obj.patch