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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-08-19 14:13:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-20 09:34:55 -0700
commit8d6c83f0ba5e1bd1e8bb2e3c7de4c276dc247f99 (patch)
tree58b777adffdaf754b97e6359a325bccdd8919346 /mm
parentb52723c5607f7684c2c0c075f86f86da0d7fb6d0 (diff)
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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: [<ffffffff8106aae7>] process_one_work+0x137/0x4a0 #1: (moom_work){+.+...}, at: [<ffffffff8106aae7>] process_one_work+0x137/0x4a0 #2: (tasklist_lock){.+.+..}, at: [<ffffffff810fafd4>] out_of_memory+0x164/0x3f0 #3: (&(&p->alloc_lock)->rlock){+.+...}, at: [<ffffffff810fa48e>] find_lock_task_mm+0x2e/0x70 Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/oom_kill.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c48c5ef3ccf..fc81cb22869 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);