From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id 676946B0031 for ; Thu, 1 Aug 2013 04:57:13 -0400 (EDT) Date: Thu, 1 Aug 2013 09:56:53 +0100 From: Russell King - ARM Linux Subject: Re: Possible deadloop in direct reclaim? Message-ID: <20130801085653.GD24642@n2100.arm.linux.org.uk> References: <89813612683626448B837EE5A0B6A7CB3B62F8F272@SC-VEXCH4.marvell.com> <000001400d38469d-a121fb96-4483-483a-9d3e-fc552e413892-000000@email.amazonses.com> <89813612683626448B837EE5A0B6A7CB3B62F8F5C3@SC-VEXCH4.marvell.com> <89813612683626448B837EE5A0B6A7CB3B62F8FE33@SC-VEXCH4.marvell.com> <51F69BD7.2060407@gmail.com> <89813612683626448B837EE5A0B6A7CB3B630BDF99@SC-VEXCH4.marvell.com> <51F9CBC0.2020006@gmail.com> <89813612683626448B837EE5A0B6A7CB3B630BE028@SC-VEXCH4.marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89813612683626448B837EE5A0B6A7CB3B630BE028@SC-VEXCH4.marvell.com> Sender: owner-linux-mm@kvack.org List-ID: To: Lisa Du Cc: KOSAKI Motohiro , Christoph Lameter , "linux-mm@kvack.org" , Mel Gorman , Bob Liu , Neil Zhang On Wed, Jul 31, 2013 at 10:19:53PM -0700, Lisa Du wrote: > >fork alloc order-1 memory for stack. Where and why alloc order-2? If it is > >arch specific code, please > >contact arch maintainer. > Yes arch do_fork allocate order-2 memory when copy_process. > Hi, Russel > What's your opinion about this question? > If we really need order-2 memory for fork, then we'd better set > CONFIG_COMPATION right? Well, I gave up trying to read the original messages because the quoting style is a total mess, so I don't have a full understanding of what the issue is. However, we have always required order-2 memory for fork, going back to the 1.x kernel days - it's fundamental to ARM to have that. The order-2 allocation os for the 1st level page table. No order-2 allocation, no page tables for the new thread. Looking at this commit: commit 05106e6a54aed321191b4bb5c9ee09538cbad3b1 Author: Rik van Riel Date: Mon Oct 8 16:33:03 2012 -0700 mm: enable CONFIG_COMPACTION by default Now that lumpy reclaim has been removed, compaction is the only way left to free up contiguous memory areas. It is time to just enable CONFIG_COMPACTION by default. it seems to indicate that everyone should have this enabled - however, the way the change has been done, anyone building from defconfigs before that change will not have that option enabled. So yes, this option should be turned on. -- 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