Re: [PATCH] getrusage: fill ru_maxrss value

[Oleg Nesterov <oleg@redhat.com>]

On 11/24, Jiri Pirko wrote:
>
> @@ -1588,6 +1589,13 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
>  				accumulate_thread_rusage(t, r);
>  				t = next_thread(t);
>  			} while (t != p);
> +			if (p->mm) {
> +				update_hiwater_rss(p->mm);
> +				if (r->ru_maxrss < p->mm->hiwater_rss)
> +					r->ru_maxrss = p->mm->hiwater_rss;

The task can free its ->mm right after the check. You need get_task_mm(),
but you can't do this under ->siglock because it takes task_lock().

I think you can move this code outside of lock_task_sighand().

Oleg.