Re: Kernel falls apart under light memory pressure (i.e. linking vmlinux)
From: KOSAKI Motohiro
Date: Sat May 21 2011 - 08:04:56 EST
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 3f44b81..d1dabc9 100644
> @@ -1426,8 +1437,13 @@ shrink_inactive_list(unsigned long nr_to_scan,
> struct zone *zone,
>
> /* Check if we should syncronously wait for writeback */
> if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
> + unsigned long nr_active, old_nr_scanned;
> set_reclaim_mode(priority, sc, true);
> + nr_active = clear_active_flags(&page_list, NULL);
> + count_vm_events(PGDEACTIVATE, nr_active);
> + old_nr_scanned = sc->nr_scanned;
> nr_reclaimed += shrink_page_list(&page_list, zone, sc);
> + sc->nr_scanned = old_nr_scanned;
> }
>
> local_irq_disable();
>
> I just tested 2.6.38.6 with the attached patch. It survived dirty_ram
> and test_mempressure without any problems other than slowness, but
> when I hit ctrl-c to stop test_mempressure, I got the attached oom.
Minchan,
I'm confused now.
If pages got SetPageActive(), should_reclaim_stall() should never return true.
Can you please explain which bad scenario was happen?
-----------------------------------------------------------------------------------------------------
static void reset_reclaim_mode(struct scan_control *sc)
{
sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC;
}
shrink_page_list()
{
(snip)
activate_locked:
SetPageActive(page);
pgactivate++;
unlock_page(page);
reset_reclaim_mode(sc); /// here
list_add(&page->lru, &ret_pages);
}
-----------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------
bool should_reclaim_stall()
{
(snip)
/* Only stall on lumpy reclaim */
if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) /// and here
return false;
-----------------------------------------------------------------------------------------------------
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