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Subject: Re: [PATCH RFC] mm/memory_hotplug: Introduce memory block types
References: <20180928150357.12942-1-david@redhat.com>
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From: Dave Hansen <dave.hansen@linux.intel.com>
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Date: Wed, 3 Oct 2018 07:07:47 -0700
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To: Vitaly Kuznetsov <vkuznets@redhat.com>, Michal Hocko <mhocko@kernel.org>
Cc: David Hildenbrand <david@redhat.com>, Kate Stewart <kstewart@linuxfoundation.org>, Rich Felker <dalias@libc.org>, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Balbir Singh <bsingharora@gmail.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, linux-mm@kvack.org, Pavel Tatashin <pavel.tatashin@microsoft.com>, Paul Mackerras <paulus@samba.org>, "H. Peter Anvin" <hpa@zytor.com>, Rashmica Gupta <rashmica.g@gmail.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, linux-s390@vger.kernel.org, Michael Neuling <mikey@neuling.org>, Stephen Hemminger <sthemmin@microsoft.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Michael Ellerman <mpe@ellerman.id.au>, linux-acpi@vger.kernel.org, Ingo Molnar <mingo@redhat.com>, xen-devel@lists.xenproject.org, Rob Herring <robh@kernel.org>, Len Brown <lenb@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>, Stephen Rothwell <sfr@canb.auug.org.au>, "mike.travis@hpe.com" <mike.travis@hpe.com>, Haiyang Zhang <haiyangz@microsoft.com>, Dan Williams <dan.j.williams@intel.com>, =?UTF-8?Q?Jonathan_Neusch=c3=a4fer?= <j.neuschaefer@gmx.net>, Nicholas Piggin <npiggin@gmail.com>, Joe Perches <joe@perches.com>, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>, Mike Rapoport <rppt@linux.vnet.ibm.com>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Oscar Salvador <osalvador@suse.de>, Juergen Gross <jgross@suse.com>, Tony Luck <tony.luck@intel.com>, Mathieu Malaterre <malat@debian.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, linux-kernel@vger.kernel.org, Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>, Philippe Ombredanne <pombredanne@nexb.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, devel@linuxdriverproject.org, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

On 10/03/2018 06:52 AM, Vitaly Kuznetsov wrote:
> It is more than just memmaps (e.g. forking udev process doing memory
> onlining also needs memory) but yes, the main idea is to make the
> onlining synchronous with hotplug.

That's a good theoretical concern.

But, is it a problem we need to solve in practice?