From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user [v2] Date: Sun, 12 Jan 2014 18:46:42 -0500 Message-ID: <52D32962.5050908@redhat.com> References: <1389380698-19361-1-git-send-email-prarit@redhat.com> <1389380698-19361-4-git-send-email-prarit@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: owner-linux-mm@kvack.org To: 7eggert@gmx.de Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Len Brown , "Rafael J. Wysocki" , Linn Crosetto , Pekka Enberg , Yinghai Lu , Andrew Morton , Toshi Kani , Tang Chen , Wen Congyang , Vivek Goyal , kosaki.motohiro@gmail.com, dyoung@redhat.com, linux-acpi@vger.kernel.org, linux-mm@kvack.org List-Id: linux-acpi@vger.kernel.org On 01/11/2014 11:35 AM, 7eggert@gmx.de wrote: > > > On Fri, 10 Jan 2014, Prarit Bhargava wrote: > >> kdump uses memmap=exactmap and mem=X values to configure the memory >> mapping for the kdump kernel. If memory is hotadded during the boot of >> the kdump kernel it is possible that the page tables for the new memory >> cause the kdump kernel to run out of memory. >> >> Since the user has specified a specific mapping ACPI Memory Hotplug should be >> disabled in this case. > > I'll ask just in case: Is it possible to want memory hotplug in spite of > using memmap=exactmap or mem=X? Good question -- I can't think of a case. When a user specifies "memmap" or "mem" IMO they are asking for a very specific memory configuration. Having extra memory added above what the user has specified seems to defeat the purpose of "memmap" and "mem". P. -- 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