From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 354056B021D for ; Tue, 1 Jun 2010 03:38:38 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o517cZos014557 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 1 Jun 2010 16:38:36 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id AC09A45DE61 for ; Tue, 1 Jun 2010 16:38:35 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 7817545DE51 for ; Tue, 1 Jun 2010 16:38:35 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 5D0681DB803F for ; Tue, 1 Jun 2010 16:38:35 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 136041DB803A for ; Tue, 1 Jun 2010 16:38:35 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [patch -mm 11/18] oom: avoid oom killer for lowmem allocations In-Reply-To: References: Message-Id: <20100601163813.2466.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 1 Jun 2010 16:38:34 +0900 (JST) Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Rik van Riel , Nick Piggin , Oleg Nesterov , KAMEZAWA Hiroyuki , Balbir Singh , linux-mm@kvack.org List-ID: > 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 when __GFP_NOFAIL is > not used so that the task can perhaps recover or try again later. > > 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. > > high_zoneidx is gfp_zone(gfp_flags), meaning that ZONE_NORMAL will be the > default for all allocations that are not __GFP_DMA, __GFP_DMA32, > __GFP_HIGHMEM, and __GFP_MOVABLE on kernels configured to support those > flags. Testing for high_zoneidx being less than ZONE_NORMAL will only > return true for allocations that have either __GFP_DMA or __GFP_DMA32. > > Signed-off-by: David Rientjes ack -- 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