linux-kernel - Re: [PATCH] mmtom: Prevent shrinking of active anon lru list in case of no swap space V2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <28c262360905140535w4bfdbbccp55f395daa18fbf0e@mail.gmail.com>
Date:	Thu, 14 May 2009 21:35:07 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH] mmtom: Prevent shrinking of active anon lru list in case 
	of no swap space V2

On Thu, May 14, 2009 at 9:11 PM, KOSAKI Motohiro
<kosaki.motohiro@...fujitsu.com> wrote:
>> On Thu, May 14, 2009 at 8:44 PM, KOSAKI Motohiro
>> <kosaki.motohiro@...fujitsu.com> wrote:
>> >> >
>> >> > Changelog since V2
>> >> > ?o Add new function - can_reclaim_anon : it tests anon_list can be reclaim
>> >> >
>> >> > Changelog since V1
>> >> > ?o Use nr_swap_pages <= 0 in shrink_active_list to prevent scanning ?of active anon list.
>> >> >
>> >> > Now shrink_active_list is called several places.
>> >> > But if we don't have a swap space, we can't reclaim anon pages.
>> >> > So, we don't need deactivating anon pages in anon lru list.
>> >> >
>> >> > Signed-off-by: Minchan Kim <minchan.kim@...il.com>
>> >> > Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
>> >> > Cc: Johannes Weiner <hannes@...xchg.org>
>> >> > Cc: Rik van Riel <riel@...hat.com>
>> >>
>> >> looks good to me. thanks :)
>> >
>> > Grr, my fault.
>> >
>> >
>> >
>> >> ?static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
>> >> ? ? ? struct zone *zone, struct scan_control *sc, int priority)
>> >> ?{
>> >> @@ -1399,7 +1412,7 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
>> >> ? ? ? ? ? ? ? return 0;
>> >> ? ? ? }
>> >>
>> >> - ? ? if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
>> >> + ? ? if (lru == LRU_ACTIVE_ANON && can_reclaim_anon(zone, sc)) {
>> >> ? ? ? ? ? ? ? shrink_active_list(nr_to_scan, zone, sc, priority, file);
>> >> ? ? ? ? ? ? ? return 0;
>> >
>> > you shouldn't do that. if nr_swap_pages==0, get_scan_ratio return anon=0%.
>> > then, this branch is unnecessary.
>> >
>>
>> But, I think at last it can be happen following as.
>>
>> 1515         * Even if we did not try to evict anon pages at all, we want to
>> 1516         * rebalance the anon lru active/inactive ratio.
>> 1517         */
>> 1518        if (inactive_anon_is_low(zone, sc))
>> 1519                shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
>
> I pointed to shrink_list(), but you replayed shrink_zone().
> I only talked about shrink_list().
>

In shrink_zone, we call get_scan_ratio. it prevent scanning anon list.
but, in shrink_all_zones can't prevent it.

Also,  I think shrink_list is not hot patch.
So check of one condition adding is trivial

If I don't understand your point, please explain detaily


-- 
Kinds regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/