From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag Date: Sun, 10 May 2009 01:03:22 +0200 Message-ID: <200905100103.23815.rjw__1204.43033888495$1241911908$gmane$org@sisk.pl> References: <200905092337.39906.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: David Rientjes Cc: kernel-testers@vger.kernel.org, Mel Gorman , linux-kernel@vger.kernel.org, alan-jenkins@tuffmail.co.uk, jens.axboe@oracle.com, Andrew Morton , fengguang.wu@intel.com, Linus Torvalds , linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org On Sunday 10 May 2009, David Rientjes wrote: > On Sat, 9 May 2009, Rafael J. Wysocki wrote: > > > > This has been changed in the latest mmotm with Mel's page alloactor > > > patches (and I think yours should be based on mmotm). Specifically, > > > page-allocator-break-up-the-allocator-entry-point-into-fast-and-slow-paths.patch. > > > > > > Before his patchset, zonelists that had ZONE_OOM_LOCKED set for at least > > > one of their zones would unconditionally goto restart. Now, if > > > order > PAGE_ALLOC_COSTLY_ORDER, it gives up and returns NULL. Otherwise, > > > it does goto restart. > > > > > > So if your allocation has order > PAGE_ALLOC_COSTLY_ORDER, > > > > It doesn't. All of my allocations are of order 0. > > > > All order 0 allocations are implicitly __GFP_NOFAIL and will loop > endlessly unless they can't block. So if you want to simply prohibit the > oom killer from being invoked and not change the retry behavior, setting > ZONE_OOM_LOCKED for all zones will do that. If your machine hangs, it > means nothing can be reclaimed and you can't free memory via oom killing, > so there's nothing else the page allocator can do. But I want it to give up in this case instead of looping forever. Look. I have a specific problem at hand that I want to solve and the approach you suggested _clearly_ _doesn't_ _work_. I have also tried to explain to you why it doesn't work, but you're ingnoring it, so I really don't know what else I can say. OTOH, the approach suggested by Andrew _does_ _work_ regardless of your opinion about it. It's been tested and it's done the job 100% of the time. Go figure. And please stop beating the dead horse. Thanks, Rafael