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Subject[PATCH 08/12] oom: dump_tasks() use find_lock_task_mm() too
Date
dump_task() should use find_lock_task_mm() too. It is necessary for
protecting task-exiting race.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
mm/oom_kill.c | 37 ++++++++++++++++++++-----------------
1 files changed, 20 insertions(+), 17 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 35a2ecc..6360c56 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -345,35 +345,38 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
*/
static void dump_tasks(const struct mem_cgroup *mem)
{
- struct task_struct *g, *p;
+ struct task_struct *p;
+ struct task_struct *task;

printk(KERN_INFO "[ pid ] uid tgid total_vm rss cpu oom_adj "
"name\n");
- do_each_thread(g, p) {
- struct mm_struct *mm;

- if (mem && !task_in_mem_cgroup(p, mem))
+ for_each_process(p) {
+ /*
+ * We don't have is_global_init() check here, because the old
+ * code do that. printing init process is not big matter. But
+ * we don't hope to make unnecessary compatiblity breaking.
+ */
+ if (p->flags & PF_KTHREAD)
continue;
- if (!thread_group_leader(p))
+ if (mem && !task_in_mem_cgroup(p, mem))
continue;

- task_lock(p);
- mm = p->mm;
- if (!mm) {
+ task = find_lock_task_mm(p);
+ if (!task)
/*
- * total_vm and rss sizes do not exist for tasks with no
- * mm so there's no need to report them; they can't be
- * oom killed anyway.
+ * Probably oom vs task-exiting race was happen and ->mm
+ * have been detached. thus there's no need to report them;
+ * they can't be oom killed anyway.
*/
- task_unlock(p);
continue;
- }
+
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,
+ task->pid, __task_cred(task)->uid, task->tgid, task->mm->total_vm,
+ get_mm_rss(task->mm), (int)task_cpu(task), task->signal->oom_adj,
p->comm);
- task_unlock(p);
- } while_each_thread(g, p);
+ task_unlock(task);
+ }
}

static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
--
1.6.5.2




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