Oleg Nesterov wrote:
> Paranoid fix. The task can free its ->mm after the 'if (p->mm)' check.
Why this change is necessary? This routine is indirectly invoked by
taskstats_exit_send() routine called inside do_exit():
do_exit()
{
...
taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
taskstats_exit_free(tidstats);
delayacct_tsk_exit(tsk);
exit_mm(tsk);
...
}
The mm is freed in exit_mm(), right?
- jay
>
> Signed-off-by: Oleg Nesterov <[email protected]>
>
> --- STATS/kernel/tsacct.c~3_mm 2006-10-27 01:03:26.000000000 +0400
> +++ STATS/kernel/tsacct.c 2006-10-29 21:46:12.000000000 +0300
> @@ -80,13 +80,17 @@ void bacct_add_tsk(struct taskstats *sta
> */
> void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
> {
> + struct mm_struct *mm;
> +
> /* convert pages-jiffies to Mbyte-usec */
> stats->coremem = jiffies_to_usecs(p->acct_rss_mem1) * PAGE_SIZE / MB;
> stats->virtmem = jiffies_to_usecs(p->acct_vm_mem1) * PAGE_SIZE / MB;
> - if (p->mm) {
> + mm = get_task_mm(p);
> + if (mm) {
> /* adjust to KB unit */
> - stats->hiwater_rss = p->mm->hiwater_rss * PAGE_SIZE / KB;
> - stats->hiwater_vm = p->mm->hiwater_vm * PAGE_SIZE / KB;
> + stats->hiwater_rss = mm->hiwater_rss * PAGE_SIZE / KB;
> + stats->hiwater_vm = mm->hiwater_vm * PAGE_SIZE / KB;
> + mmput(mm);
> }
> stats->read_char = p->rchar;
> stats->write_char = p->wchar;
>
-
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