On 06/12/2015 04:53 PM, Oleg Nesterov wrote:
On 06/12, Oleg Nesterov wrote:
On 06/12, Ingo Molnar wrote:
* Linus Torvalds <torva...@linux-foundation.org> wrote:
So I think the only issue is that ->mm can become NULL when the thread group
leader dies - a non-NULL mm should always be shared among all threads.
Indeed, we do that in exit_mm().
Yes,
So we could add tsk->mm_leader or so,
No, no, please do not. Just do something like
for_each_process(p) {
for_each_thread(p, t) {
if (t->mm) {
do_something(t->mm);
break;
}
}
}
But either way I don't understand what protects this ->mm. Perhaps this needs
find_lock_task_mm().
And, I don't understand this code, probably this doesn't matter, but.
unpin_all() is probably fine, but xen_mm_pin_all() can race with fork()
and miss the new child. Is it OK?
Currently xen_mm_pin_all() is only called in the suspend path, out of
stop_machine(), so presumably at that time fork is not possible.
-boris
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