From 8d6c83f0ba5e1bd1e8bb2e3c7de4c276dc247f99 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Thu, 19 Aug 2010 14:13:39 -0700 Subject: [PATCH] oom: __task_cred() need rcu_read_lock() dump_tasks() needs to hold the RCU read lock around its access of the target task's UID. To this end it should use task_uid() as it only needs that one thing from the creds. The fact that dump_tasks() holds tasklist_lock is insufficient to prevent the target process replacing its credentials on another CPU. Then, this patch change to call rcu_read_lock() explicitly. =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- mm/oom_kill.c:410 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 4 locks held by kworker/1:2/651: #0: (events){+.+.+.}, at: [] process_one_work+0x137/0x4a0 #1: (moom_work){+.+...}, at: [] process_one_work+0x137/0x4a0 #2: (tasklist_lock){.+.+..}, at: [] out_of_memory+0x164/0x3f0 #3: (&(&p->alloc_lock)->rlock){+.+...}, at: [] find_lock_task_mm+0x2e/0x70 Signed-off-by: KOSAKI Motohiro Signed-off-by: David Howells Acked-by: Paul E. McKenney Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index c48c5ef3ccfd..fc81cb22869e 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -372,7 +372,7 @@ static void dump_tasks(const struct mem_cgroup *mem) } pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n", - task->pid, __task_cred(task)->uid, task->tgid, + task->pid, task_uid(task), task->tgid, task->mm->total_vm, get_mm_rss(task->mm), task_cpu(task), task->signal->oom_adj, task->signal->oom_score_adj, task->comm); -- 2.39.2