Re: [patch 12/12] mm: correctly synchronize rss-counters at exit/exec

[Hugh Dickins <hughd@google.com>]

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On Thu, 7 Jun 2012, Linus Torvalds wrote:
> No, this is apparently that same "almost there" patch from Oleg. I
> guarantee that it's wrong.
> 
>                 Linus
> 
> ---
> 
> [ This part, to be exact: ]
> 
> On Thu, Jun 7, 2012 at 6:16 PM, Hugh Dickins <hughd@google.com> wrote:
> > --- a/kernel/tsacct.c
> > +++ b/kernel/tsacct.c
> > @@ -91,6 +91,7 @@ void xacct_add_tsk(struct taskstats *stats, struct task_struct *p)
> >        stats->virtmem = p->acct_vm_mem1 * PAGE_SIZE / MB;
> >        mm = get_task_mm(p);
> >        if (mm) {
> > +               sync_mm_rss(mm);
> >                /* adjust to KB unit */
> >                stats->hiwater_rss   = get_mm_hiwater_rss(mm) * PAGE_SIZE / KB;
> >                stats->hiwater_vm    = get_mm_hiwater_vm(mm)  * PAGE_SIZE / KB;
> > --

Yup.

It does look as if Oleg's intent (last chance to update xacct stats
from dying current task) would be well served by changing that to

		if (p == current)
			sync_mm_rss(mm);

but I've made too many hurried decisions recently to sign off on that.

Hugh