dump_tasks() can call __task_cred() safely because we are holding
tasklist_lock. but rcu lock validator don't have enough knowledge and
it makes following annoying warning.
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@xxxxxxxxxxxxxx>
---
mm/oom_kill.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c48c5ef..57c05f7 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -371,11 +371,13 @@ static void dump_tasks(const struct mem_cgroup *mem)
continue;
}
+ rcu_read_lock();
pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n",
task->pid, __task_cred(task)->uid, 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);
+ rcu_read_unlock();
task_unlock(task);
}
}
--
1.6.5.2
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