From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id E3F896B0071 for ; Thu, 11 Feb 2010 09:09:09 -0500 (EST) Message-ID: <4B740F7A.5020702@redhat.com> Date: Thu, 11 Feb 2010 09:08:58 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [patch 6/7 -mm] oom: avoid oom killer for lowmem allocations References: <4B7383D5.2080904@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: Andrew Morton , KAMEZAWA Hiroyuki , Nick Piggin , Andrea Arcangeli , Balbir Singh , Lubos Lunak , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On 02/11/2010 04:19 AM, David Rientjes wrote: > On Wed, 10 Feb 2010, Rik van Riel wrote: > >>> 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; >> >> Are there architectures that only have one memory zone? >> > > It actually ends up not to matter because of how gfp_zone() is implemented > (and you can do it with mem= on architectures with larger ZONE_DMA zones > such as ia64). ZONE_NORMAL is always guaranteed to be defined regardless > of architecture or configuration because it's the default zone for memory > allocation unless specified by a bit in GFP_ZONEMASK, it doesn't matter > whether it actually has memory or not. high_zoneidx in this case is just > gfp_zone(gfp_flags) which always defaults to ZONE_NORMAL when one of the > GFP_ZONEMASK bits is not set. Thus, the only way to for the conditional > in this patch to be true is when __GFP_DMA, or __GFP_DMA32 for x86_64, is > passed to the page allocator and CONFIG_ZONE_DMA or CONFIG_ZONE_DMA32 is > enabled, respectively. Fair enough. Acked-by: Rik van Riel -- All rights reversed. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org