From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f71.google.com (mail-lf0-f71.google.com [209.85.215.71]) by kanga.kvack.org (Postfix) with ESMTP id 7DED66B0269 for ; Wed, 21 Sep 2016 08:05:11 -0400 (EDT) Received: by mail-lf0-f71.google.com with SMTP id s64so8699187lfs.1 for ; Wed, 21 Sep 2016 05:05:11 -0700 (PDT) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id h4si35514838wje.203.2016.09.21.05.05.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Sep 2016 05:05:10 -0700 (PDT) Received: by mail-wm0-f68.google.com with SMTP id 133so8208111wmq.2 for ; Wed, 21 Sep 2016 05:05:10 -0700 (PDT) Date: Wed, 21 Sep 2016 14:05:08 +0200 From: Michal Hocko Subject: Re: [PATCH] memory-hotplug: Fix bad area access on dissolve_free_huge_pages() Message-ID: <20160921120507.GG10300@dhcp22.suse.cz> References: <1473755948-13215-1-git-send-email-rui.teng@linux.vnet.ibm.com> <57D83821.4090804@linux.intel.com> <57D97CAF.7080005@linux.intel.com> <566c04af-c937-cbe0-5646-2cc2c816cc3f@linux.vnet.ibm.com> <57DC1CE0.5070400@linux.intel.com> <7e642622-72ee-87f6-ceb0-890ce9c28382@linux.vnet.ibm.com> <57E14D64.6090609@linux.intel.com> <57E17531.6050008@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57E17531.6050008@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Rui Teng , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Naoya Horiguchi , "Kirill A . Shutemov" , Vlastimil Babka , Mike Kravetz , "Aneesh Kumar K . V" , Paul Gortmaker , Santhosh G On Tue 20-09-16 10:43:13, Dave Hansen wrote: > On 09/20/2016 08:52 AM, Rui Teng wrote: > > On 9/20/16 10:53 PM, Dave Hansen wrote: > ... > >> That's good, but aren't we still left with a situation where we've > >> offlined and dissolved the _middle_ of a gigantic huge page while the > >> head page is still in place and online? > >> > >> That seems bad. > >> > > What about refusing to change the status for such memory block, if it > > contains a huge page which larger than itself? (function > > memory_block_action()) > > How will this be visible to users, though? That sounds like you simply > won't be able to offline memory with gigantic huge pages. I might be missing something but Is this any different from a regular failure when the memory cannot be freed? I mean /sys/devices/system/memory/memory API doesn't give you any hint whether the memory in the particular block is used and unmigrateable. -- 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