From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 939696B0260 for ; Mon, 6 Nov 2017 13:04:17 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id s75so13458601pgs.12 for ; Mon, 06 Nov 2017 10:04:17 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id b5si11537820pgr.120.2017.11.06.10.04.16 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 06 Nov 2017 10:04:16 -0800 (PST) Date: Mon, 6 Nov 2017 19:04:06 +0100 From: Michal Hocko Subject: Re: Guaranteed allocation of huge pages (1G) using movablecore=N doesn't seem to work at all Message-ID: <20171106180406.diowlwanvucnwkbp@dhcp22.suse.cz> References: <20171106171150.7a2lent6vdrewsk7@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Maxim Levitsky Cc: linux-mm@kvack.org On Mon 06-11-17 19:36:38, Maxim Levitsky wrote: > Isn't this a non backward compatible change? Why to remove an optional non > default option for use cases like mine. Well, strictly speaking it is. The reality is that with the current implementation the option breaks the hotplug usecase. I can see your argument about the opt in and we might need to hold on this patch for merging uut it seems that http://lkml.kernel.org/r/20171003072619.8654-1-mhocko@kernel.org is not the problem you are seeing. > I won't argue with you on this, but my question was different, and was why > the kernel can't move other pages from moveable zone in my case. OK, I have re-read your original report where you say : This was tested on 4.14.0-rc5 (my custom compiled) and on several : older kernels (4.10,4.12,4.13) from ubuntu repositories. Does that mean that this a new regression in 4.14-rc5 or you see the problem in other kernels too? If this a new rc5 thing then 79b63f12abcb ("mm, hugetlb: do not allocate non-migrateable gigantic pages from movable zones") might be related. Although it shouldn't if hugepages_treat_as_movable is enabled. I wouldn't be all that surprised if this was an older issue, though. If I look at pfn_range_valid_gigantic it seems that the page count check makes it just too easy to fail even on migratable memory. To be honest I consider the giga pages runtime support rather fragile and that is why I wasn't very much afraid to remove hacks that allow breaking other usecases. -- Michal Hocko SUSE Labs -- 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