Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754851AbZGAIzx (ORCPT ); Wed, 1 Jul 2009 04:55:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751051AbZGAIzp (ORCPT ); Wed, 1 Jul 2009 04:55:45 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:52581 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751016AbZGAIzp (ORCPT ); Wed, 1 Jul 2009 04:55:45 -0400 Date: Tue, 30 Jun 2009 08:27:20 +0200 From: Pavel Machek To: Andrew Morton Cc: Linus Torvalds , penberg@cs.helsinki.fi, arjan@infradead.org, linux-kernel@vger.kernel.org, cl@linux-foundation.org, npiggin@suse.de, David Rientjes , Mel Gorman Subject: Re: upcoming kerneloops.org item: get_page_from_freelist Message-ID: <20090630062720.GA1351@ucw.cz> References: <4A426825.80905@cs.helsinki.fi> <20090624113037.7d72ed59.akpm@linux-foundation.org> <20090624120617.1e6799b5.akpm@linux-foundation.org> <20090624123624.26c93459.akpm@linux-foundation.org> <20090624130121.99321cca.akpm@linux-foundation.org> <20090624145615.2ff9e56e.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090624145615.2ff9e56e.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1754 Lines: 40 > > This is not a new concept. oom has never been "immediately kill". > > Well, it has been immediate for a long time. A couple of reasons which > I can recall: > > - A page-allocating process will oom-kill another process in the > expectation that the killing will free up some memory. If the > oom-killed process remains stuck in the page allocator, that doesn't > work. > > - The oom-killed process might be holding locks (typically fs locks). > This can cause an arbitrary number of other processes to be blocked. > So to get the system unstuck we need the oom-killed process to > immediately exit the page allocator, to handle the NULL return and to > drop those locks. > > There may be other reasons - it was all a long time ago, and I've never > personally hacked on the oom-killer much and I never get oom-killed. > But given the amount of development work which goes on in there, some > people must be getting massacred. > > > A long time ago, the Suse kernel shipped with a largely (or > completely?) disabled oom-killer. It removed the > retry-small-allocations-for-ever logic and simply returned NULL to the > caller. I never really understood what problem/thinking led Andrea to > do that. I guess he was trying to get huge 32bit highmem machines to work... On such systems, kmalloc failures will eventually get you... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/