* Oleg Nesterov <o...@redhat.com> wrote:

> On 09/22, Linus Torvalds wrote:
> >
> > However, this now becomes a pattern for the series, and that just makes me 
> > think
> >
> >     "Why is this not a 'for_each_mm()' pattern helper?"
> 
> And we already have other users. And note that oom_kill_process() does _not_
> follow this pattern and that is why it is buggy.
> 
> So this is funny, but I was thinking about almost the same, something like
> 
>       struct task_struct *next_task_with_mm(struct task_struct *p)
>       {
>               struct task_struct *t;
> 
>               p = p->group_leader;
>               while ((p = next_task(p)) != &init_task) {
>                       if (p->flags & PF_KTHREAD)
>                               continue;
> 
>                       t = find_lock_task_mm(p);
>                       if (t)
>                               return t;
>               }
> 
>               return NULL;
>       }
> 
>       #define for_each_task_lock_mm(p)
>               for (p = &init_task; (p = next_task_with_mm(p)); task_unlock(p))
> 
> 
> So that you can do
> 
>       for_each_task_lock_mm(p) {
>               do_something_with(p->mm);
> 
>               if (some_condition()) {
>                       // UNFORTUNATELY you can't just do "break"
>                       task_unlock(p);
>                       break;
>               }
>       }
> 
> do you think it makes sense?

Sure, I'm inclined to use the above code from you.

> In fact it can't be simpler, we can move task_unlock() into 
> next_task_with_mm(), 
> it can check ->mm != NULL or p != init_task.

s/can't/can ?

But even with that I'm not sure I can parse your suggestion. Got some (pseudo) 
code
perhaps?

Thanks,

        Ingo
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