Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756545Ab0BLBcM (ORCPT ); Thu, 11 Feb 2010 20:32:12 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:55554 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753340Ab0BLBcK (ORCPT ); Thu, 11 Feb 2010 20:32:10 -0500 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 12 Feb 2010 10:28:41 +0900 From: KAMEZAWA Hiroyuki To: David Rientjes Cc: Andrew Morton , Rik van Riel , Nick Piggin , Andrea Arcangeli , Balbir Singh , Lubos Lunak , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch 6/7 -mm] oom: avoid oom killer for lowmem allocations Message-Id: <20100212102841.fa148baf.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.7.1 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2897 Lines: 80 On Wed, 10 Feb 2010 08:32:21 -0800 (PST) David Rientjes wrote: > If memory has been depleted in lowmem zones even with the protection > afforded to it by /proc/sys/vm/lowmem_reserve_ratio, it is unlikely that > killing current users will help. The memory is either reclaimable (or > migratable) already, in which case we should not invoke the oom killer at > all, or it is pinned by an application for I/O. Killing such an > application may leave the hardware in an unspecified state and there is > no guarantee that it will be able to make a timely exit. > > Lowmem allocations are now failed in oom conditions so that the task can > perhaps recover or try again later. Killing current is an unnecessary > result for simply making a GFP_DMA or GFP_DMA32 page allocation and no > lowmem allocations use the now-deprecated __GFP_NOFAIL bit so retrying is > unnecessary. > > Previously, the heuristic provided some protection for those tasks with > CAP_SYS_RAWIO, but this is no longer necessary since we will not be > killing tasks for the purposes of ISA allocations. > > Signed-off-by: David Rientjes >From viewpoint of panic-on-oom lover, this patch seems to cause regression. please do this check after sysctl_panic_on_oom == 2 test. I think it's easy. So, temporary Nack to this patch itself. And I think calling notifier is not very bad in the situation. == void out_of_memory() ..snip.. blocking_notifier_call_chain(&oom_notify_list, 0, &freed); So, if (sysctl_panic_on_oom == 2) { dump_header(NULL, gfp_mask, order, NULL); panic("out of memory. Compulsory panic_on_oom is selected.\n"); } if (gfp_zone(gfp_mask) < ZONE_NORMAL) /* oom-kill is useless if lowmem is exhausted. */ return; is better. I think. Thanks, -Kame > --- > mm/page_alloc.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1914,6 +1914,9 @@ rebalance: > * running out of options and have to consider going OOM > */ > if (!did_some_progress) { > + /* The oom killer won't necessarily free lowmem */ > + if (high_zoneidx < ZONE_NORMAL) > + goto nopage; > if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) { > if (oom_killer_disabled) > goto nopage; > -- > 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/