From: Chen Ridong <chenridong@huawei.com> mainline inclusion from mainline-v6.19 commit 592a68212c5664bcaa88f24ed80bf791282790fe category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8422 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- A warnning was detected: WARNING: suspicious RCU usage 6.19.0-rc7-next-20260129+ #1101 Tainted: G O kernel/cgroup/dmem.c:456 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by insmod/532: #0: ffffffff85e78b38 (dmemcg_lock){+.+.}-dmem_cgroup_unregister_region+ stack backtrace: CPU: 2 UID: 0 PID: 532 Comm: insmod Tainted: 6.19.0-rc7-next- Tainted: [O]=OOT_MODULE Call Trace: <TASK> dump_stack_lvl+0xb0/0xd0 lockdep_rcu_suspicious+0x151/0x1c0 dmem_cgroup_unregister_region+0x1e2/0x380 ? __pfx_dmem_test_init+0x10/0x10 [dmem_uaf] dmem_test_init+0x65/0xff0 [dmem_uaf] do_one_initcall+0xbb/0x3a0 The macro list_for_each_rcu() must be used within an RCU read-side critical section (between rcu_read_lock() and rcu_read_unlock()). Using it outside that context, as seen in dmem_cgroup_unregister_region(), triggers the lockdep warning because the RCU protection is not guaranteed. Replace list_for_each_rcu() with list_for_each_entry_safe(), which is appropriate for traversal under spinlock protection where nodes may be deleted. Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup") Cc: stable@vger.kernel.org # v6.14+ Signed-off-by: Chen Ridong <chenridong@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Liu Kai <liukai284@huawei.com> --- kernel/cgroup/dmem.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c index fc67efa8e1a9..e6a20de91332 100644 --- a/kernel/cgroup/dmem.c +++ b/kernel/cgroup/dmem.c @@ -422,7 +422,7 @@ static void dmemcg_free_region(struct kref *ref) */ void dmem_cgroup_unregister_region(struct dmem_cgroup_region *region) { - struct list_head *entry; + struct dmem_cgroup_pool_state *pool, *next; if (!region) return; @@ -432,10 +432,7 @@ void dmem_cgroup_unregister_region(struct dmem_cgroup_region *region) /* Remove from global region list */ list_del_rcu(®ion->region_node); - list_for_each_rcu(entry, ®ion->pools) { - struct dmem_cgroup_pool_state *pool = - container_of(entry, typeof(*pool), region_node); - + list_for_each_entry_safe(pool, next, ®ion->pools, region_node) { list_del_rcu(&pool->css_node); } -- 2.34.1