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From: Muchun Song In-Reply-To: Date: Tue, 23 Jul 2024 19:23:02 +0800 Cc: Muchun Song , Andrew Morton , Johannes Weiner , Nhat Pham , Linux Memory Management List , LKML , Michal Hocko , Roman Gushchin , shakeel.butt@linux.dev Content-Transfer-Encoding: quoted-printable Message-Id: <1E56E5B4-7003-4EF4-98F7-C1FC30B2DE1D@linux.dev> References: <65b7d88b-af4f-4869-9322-e38910abce6d@suse.cz> To: Vlastimil Babka X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 8ts6dm9cf8qrybdpiwtjz15bf3ek6oo9 X-Rspamd-Queue-Id: 1B38F4000A X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1721733829-582106 X-HE-Meta: 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 lYc9TGII /vdyTFxkPGREWrUG8oCDg0cUNXp1U9cPjpImcoAbLcD0TP9xiOKkS8j2doUucdYHgA0WunDl4tqbpiy08tyOGI2jlTQS5/sTbpfCoBOGTW0MOnJHJaCAzU9m05ovjok+7Dk5BhBigQheISmqSfM+kRK2jcuMFWZIEbILff6d69oJT5Y5yD151SZq25fYP+jEFCjx/erLbQ8SX03q2XYBuUW+CJaOCfb6BIcV8z+UklGHxFvwO4CvzsF+JmMj4jEdTPRpT5UJ5AzBCG0DCcsMc6XywqOMUQiB0mnyCy2Y+wrfyHRLsecziNLpd3xbf7U1mapoQ 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: > On Jul 18, 2024, at 19:20, Muchun Song wrote: >=20 >=20 >=20 >> On Jul 18, 2024, at 18:30, Vlastimil Babka wrote: >>=20 >> =EF=BB=BFOn 7/18/24 10:36 AM, Muchun Song wrote: >>> The mem_cgroup_from_slab_obj() is supposed to be called under rcu >>> lock or cgroup_mutex or others which could prevent returned memcg >>> from being freed. Fix it by adding missing rcu read lock. >>=20 >> Was the UAF ever observed, or is this due to code review? >=20 > Just code review. >=20 > Thanks. >=20 >> Should there be some lockdep_assert somwhere? >>=20 >=20 > It=E2=80=99s a good option to improve this. Maybe = mem_cgroup_from_slab_obj() is a good place. I added it to obj_cgroup_memcg() [1]. And CC memory cgroup maintainers = to this thread. [1] = https://lore.kernel.org/linux-mm/20859F67-A80C-4FD0-990C-40C70905E55B@linu= x.dev/T/ >=20 >>> Fixes: 0a97c01cd20bb ("list_lru: allow explicit memcg and NUMA node = selection) >>> Signed-off-by: Muchun Song >>> --- >>> mm/list_lru.c | 24 ++++++++++++++++++------ >>> 1 file changed, 18 insertions(+), 6 deletions(-) >>>=20 >>> diff --git a/mm/list_lru.c b/mm/list_lru.c >>> index 3fd64736bc458..225da0778a3be 100644 >>> --- a/mm/list_lru.c >>> +++ b/mm/list_lru.c >>> @@ -85,6 +85,7 @@ list_lru_from_memcg_idx(struct list_lru *lru, int = nid, int idx) >>> } >>> #endif /* CONFIG_MEMCG_KMEM */ >>>=20 >>> +/* The caller must ensure the memcg lifetime. */ >>> bool list_lru_add(struct list_lru *lru, struct list_head *item, int = nid, >>> struct mem_cgroup *memcg) >>> { >>> @@ -109,14 +110,20 @@ EXPORT_SYMBOL_GPL(list_lru_add); >>>=20 >>> bool list_lru_add_obj(struct list_lru *lru, struct list_head *item) >>> { >>> + bool ret; >>> int nid =3D page_to_nid(virt_to_page(item)); >>> - struct mem_cgroup *memcg =3D list_lru_memcg_aware(lru) ? >>> - mem_cgroup_from_slab_obj(item) : NULL; >>> + struct mem_cgroup *memcg; >>>=20 >>> - return list_lru_add(lru, item, nid, memcg); >>> + rcu_read_lock(); >>> + memcg =3D list_lru_memcg_aware(lru) ? = mem_cgroup_from_slab_obj(item) : NULL; >>> + ret =3D list_lru_add(lru, item, nid, memcg); >>> + rcu_read_unlock(); >>> + >>> + return ret; >>> } >>> EXPORT_SYMBOL_GPL(list_lru_add_obj); >>>=20 >>> +/* The caller must ensure the memcg lifetime. */ >>> bool list_lru_del(struct list_lru *lru, struct list_head *item, int = nid, >>> struct mem_cgroup *memcg) >>> { >>> @@ -139,11 +146,16 @@ EXPORT_SYMBOL_GPL(list_lru_del); >>>=20 >>> bool list_lru_del_obj(struct list_lru *lru, struct list_head *item) >>> { >>> + bool ret; >>> int nid =3D page_to_nid(virt_to_page(item)); >>> - struct mem_cgroup *memcg =3D list_lru_memcg_aware(lru) ? >>> - mem_cgroup_from_slab_obj(item) : NULL; >>> + struct mem_cgroup *memcg; >>>=20 >>> - return list_lru_del(lru, item, nid, memcg); >>> + rcu_read_lock(); >>> + memcg =3D list_lru_memcg_aware(lru) ? = mem_cgroup_from_slab_obj(item) : NULL; >>> + ret =3D list_lru_del(lru, item, nid, memcg); >>> + rcu_read_unlock(); >>> + >>> + return ret; >>> } >>> EXPORT_SYMBOL_GPL(list_lru_del_obj); >>>=20 >>=20