Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932231Ab1DZGiV (ORCPT ); Tue, 26 Apr 2011 02:38:21 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:33156 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932109Ab1DZGiT (ORCPT ); Tue, 26 Apr 2011 02:38:19 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Dave Young Subject: Re: [PATCH 1/2] virtio_balloon: disable oom killer when fill balloon Cc: kosaki.motohiro@jp.fujitsu.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20110426052916.GA11933@darkstar> References: <20110426052916.GA11933@darkstar> Message-Id: <20110426154037.F38B.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Tue, 26 Apr 2011 15:38:16 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2293 Lines: 62 > When memory pressure is high, virtio ballooning will probably cause oom killing. > Even if alloc_page with GFP_NORETRY itself does not directly trigger oom it > will make memory becoming low then memory alloc of other processes will trigger > oom killing. It is not desired behaviour. > > Here disable oom killer in fill_balloon to address this issue. > > Signed-off-by: Dave Young > --- > drivers/virtio/virtio_balloon.c | 3 +++ > 1 file changed, 3 insertions(+) > > --- linux-2.6.orig/drivers/virtio/virtio_balloon.c 2010-10-13 10:14:38.000000000 +0800 > +++ linux-2.6/drivers/virtio/virtio_balloon.c 2011-04-26 11:38:43.979785141 +0800 > @@ -25,6 +25,7 @@ > #include > #include > #include > +#include > > struct virtio_balloon > { > @@ -102,6 +103,7 @@ static void fill_balloon(struct virtio_b > /* We can only do one array worth at a time. */ > num = min(num, ARRAY_SIZE(vb->pfns)); > > + oom_killer_disable(); I think this patch need proper comment at least. My first impression is, "Hm, __GFP_NORETRY should prevent oom, why is this necessary?". So, this actually prevent _another_ thread call out_of_memory(). Also, Here doesn't have any exclusion against hibernation (ie another oom_killer_disable() callsite). It should be described why lock is unnecessary. Thanks. > for (vb->num_pfns = 0; vb->num_pfns < num; vb->num_pfns++) { > struct page *page = alloc_page(GFP_HIGHUSER | __GFP_NORETRY | > __GFP_NOMEMALLOC | __GFP_NOWARN); > @@ -119,6 +121,7 @@ static void fill_balloon(struct virtio_b > vb->num_pages++; > list_add(&page->lru, &vb->pages); > } > + oom_killer_enable(); > > /* Didn't get any? Oh well. */ > if (vb->num_pfns == 0) > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/