[patch 4/9] oom: Add missing rcu protection of __task_cred() in dump_tasks

Thomas Gleixner
2009-12-10T00:55:13Z

[-- Attachment #1: oom-fix-missing-rcu-protection-of-__task_cred.patch --]
[-- Type: text/plain, Size: 995 bytes --]

dump_tasks accesses __task_cred() without being in a RCU read side
critical section. tasklist_lock is not protecting that when
CONFIG_TREE_PREEMPT_RCU=y.

Add a rcu_read_lock/unlock() section around the code which accesses
__task_cred().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
---
mm/oom_kill.c | 3 +++
1 file changed, 3 insertions(+)

Index: linux-2.6-tip/mm/oom_kill.c
===================================================================
--- linux-2.6-tip.orig/mm/oom_kill.c
+++ linux-2.6-tip/mm/oom_kill.c
@@ -329,10 +329,13 @@ static void dump_tasks(const struct mem_
task_unlock(p);
continue;
}
+ /* Protect __task_cred() access */
+ rcu_read_lock();
printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n",
p->pid, __task_cred(p)->uid, p->tgid, mm->total_vm,
get_mm_rss(mm), (int)task_cpu(p), p->signal->oom_adj,
p->comm);
+ rcu_read_unlock();
task_unlock(p);
} while_each_thread(g, p);
}