On 07/14, David Ahern wrote:
>
> On 7/14/15 1:47 PM, Oleg Nesterov wrote:
>>>
>>> if (show_flags & TASK_DIAG_SHOW_VMA) {
>>> + /* if the request is to dump all threads of all processes
>>> + * only show VMAs for group leader.
>>> + */
>>> + if (req->dump_strategy == TASK_DIAG_DUMP_ALL_THREAD &&
>>> + !thread_group_leader(tsk))
>>> + goto done;
>>> +
>>
>> This doesn't look right, group leader can be a zombie with ->mm == NULL,
>
> Seriously?
Yes, the main thread can do sys_exit() / pthread_exit(), although this
is not that common.
> I'll find some way to track whether VMAs have been dumped for
> a pid.
In case I confused you, the thread_group_leader() check and "goto done"
above are fine, just you can't trust tsk->mm, so
>>> if (i >= n)
>>> err = fill_vma(tsk, skb, cb, &progress, show_flags);
>>
>> so this probably needs something like find_lock_task_mm().
>
> ok.
Yes, you just need to (try) find a subthread with ->mm != NULL if !tsk->mm,
find_lock_task_mm() can help.
Oleg.
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