From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 58BA46B01FD for ; Fri, 2 Apr 2010 05:13:08 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o329D5Nw010259 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Fri, 2 Apr 2010 18:13:06 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id AC6E145DE58 for ; Fri, 2 Apr 2010 18:13:05 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7F84145DE53 for ; Fri, 2 Apr 2010 18:13:05 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 5831D1DB8038 for ; Fri, 2 Apr 2010 18:13:05 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id F1612E38001 for ; Fri, 2 Apr 2010 18:13:04 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH]vmscan: handle underflow for get_scan_ratio In-Reply-To: <20100401151639.a030fb10.akpm@linux-foundation.org> References: <20100331145602.03A7.A69D9226@jp.fujitsu.com> <20100401151639.a030fb10.akpm@linux-foundation.org> Message-Id: <20100402180812.646D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Date: Fri, 2 Apr 2010 18:13:04 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: kosaki.motohiro@jp.fujitsu.com, Wu Fengguang , "Li, Shaohua" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" List-ID: > > Yeah, I don't want ignore .33-stable too. if I can't find the root caus= e > > in 2-3 days, I'll revert guilty patch anyway. > >=20 >=20 > It's a good idea to avoid fixing a bug one-way-in-stable, > other-way-in-mainline. Because then we have new code in both trees > which is different. And the -stable guys sensibly like to see code get > a bit of a shakedown in mainline before backporting it. >=20 > So it would be better to merge the "simple" patch into mainline, tagged > for -stable backporting. Then we can later implement the larger fix in > mainline, perhaps starting by reverting the "simple" fix. =2E....ok. I don't have to prevent your code maintainship. although I still= =20 think we need to fix the issue completely. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =46rom 52358cbccdfe94e0381974cd6e937bcc6b1c608b Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Fri, 2 Apr 2010 17:13:48 +0900 Subject: [PATCH] Revert "vmscan: get_scan_ratio() cleanup" Shaohua Li reported his tmpfs streaming I/O test can lead to make oom. The test uses a 6G tmpfs in a system with 3G memory. In the tmpfs, there are 6 copies of kernel source and the test does kbuild for each copy. His investigation shows the test has a lot of rotated anon pages and quite few file pages, so get_scan_ratio calculates percent[0] (i.e. scanning percent for anon) to be zero. Actually the percent[0] shoule be a big value, but our calculation round it to zero. Although before commit 84b18490, we have the same sick too. but the old logic can rescue percent[0]=3D=3D0 case only when priority=3D=3D0. It had h= ided the real issue. I didn't think merely streaming io can makes percent[0]=3D= =3D0 && priority=3D=3D0 situation. but I was wrong. So, definitely we have to fix such tmpfs streaming io issue. but anyway I revert the regression commit at first. This reverts commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26. Reported-by: Shaohua Li Signed-off-by: KOSAKI Motohiro --- mm/vmscan.c | 23 +++++++++-------------- 1 files changed, 9 insertions(+), 14 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 79c8098..cb3947e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1535,13 +1535,6 @@ static void get_scan_ratio(struct zone *zone, struct= scan_control *sc, unsigned long ap, fp; struct zone_reclaim_stat *reclaim_stat =3D get_reclaim_stat(zone, sc); =20 - /* If we have no swap space, do not bother scanning anon pages. */ - if (!sc->may_swap || (nr_swap_pages <=3D 0)) { - percent[0] =3D 0; - percent[1] =3D 100; - return; - } - anon =3D zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); file =3D zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + @@ -1639,20 +1632,22 @@ static void shrink_zone(int priority, struct zone *= zone, unsigned long nr_reclaimed =3D sc->nr_reclaimed; unsigned long nr_to_reclaim =3D sc->nr_to_reclaim; struct zone_reclaim_stat *reclaim_stat =3D get_reclaim_stat(zone, sc); + int noswap =3D 0; =20 - get_scan_ratio(zone, sc, percent); + /* If we have no swap space, do not bother scanning anon pages. */ + if (!sc->may_swap || (nr_swap_pages <=3D 0)) { + noswap =3D 1; + percent[0] =3D 0; + percent[1] =3D 100; + } else + get_scan_ratio(zone, sc, percent); =20 for_each_evictable_lru(l) { int file =3D is_file_lru(l); unsigned long scan; =20 - if (percent[file] =3D=3D 0) { - nr[l] =3D 0; - continue; - } - scan =3D zone_nr_lru_pages(zone, sc, l); - if (priority) { + if (priority || noswap) { scan >>=3D priority; scan =3D (scan * percent[file]) / 100; } --=20 1.6.5.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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