From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: [PATCH v2 3/8] mm/memory_hotplug: arch_remove_memory() and
 __remove_pages() with CONFIG_MEMORY_HOTPLUG
References: <20190507183804.5512-1-david@redhat.com>
 <20190507183804.5512-4-david@redhat.com>
 <CAPcyv4jpnKjeP3QEvF3_9CzdZhtFXN2nMU7P-Ee7y06J3bGZ0A@mail.gmail.com>
From: David Hildenbrand <david@redhat.com>
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Date: Mon, 13 May 2019 09:48:31 +0200
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To: Dan Williams <dan.j.williams@intel.com>, Michal Hocko <mhocko@suse.com>, Oscar Salvador <osalvador@suse.com>
Cc: Linux MM <linux-mm@kvack.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-ia64@vger.kernel.org, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, linux-s390 <linux-s390@vger.kernel.org>, Linux-sh <linux-sh@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Rich Felker <dalias@libc.org>, Dave Hansen <dave.hansen@linux.intel.com>, Andy Lutomirski <luto@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>, Mike Rapoport <rppt@linux.ibm.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Alex Deucher <alexander.deucher@amd.com>, "David S. Miller" <davem@davemloft.net>, Mark Brown <broonie@kernel.org>, Chris Wilson <chris@chris-wilson.co.uk>, Christophe Leroy <christophe.leroy@c-s.fr>, Nicholas Piggin <npiggin@gmail.com>, Vasily Gorbik <gor@linux.ibm.com>, Rob Herring <robh@kernel.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, "mike.travis@hpe.com" <mike.travis@hpe.com>, Andrew Banman <andrew.banman@hpe.com>, Pavel Tatashin <pasha.tatashin@soleen.com>, Wei Yang <richardw.yang@linux.intel.com>, Arun KS <arunks@codeaurora.org>, Qian Cai <cai@lca.pw>, Mathieu Malaterre <malat@debian.org>, Baoquan He <bhe@redhat.com>, Logan Gunthorpe <logang@deltatee.com>
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On 07.05.19 23:02, Dan Williams wrote:
> On Tue, May 7, 2019 at 11:38 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> Let's prepare for better error handling while adding memory by allowing
>> to use arch_remove_memory() and __remove_pages() even if
>> CONFIG_MEMORY_HOTREMOVE is not set. CONFIG_MEMORY_HOTREMOVE effectively
>> covers
>> - Offlining of system ram (memory block devices) - offline_pages()
>> - Unplug of system ram - remove_memory()
>> - Unplug/remap of device memory - devm_memremap()
>>
>> This allows e.g. for handling like
>>
>> arch_add_memory()
>> rc = do_something();
>> if (rc) {
>>         arch_remove_memory();
>> }
>>
>> Whereby do_something() will for example be memory block device creation
>> after it has been factored out.
> 
> What's left after this? Can we just get rid of CONFIG_MEMORY_HOTREMOVE
> option completely when CONFIG_MEMORY_HOTPLUG is enabled? It's not
> clear to me why there was ever the option to compile out the remove
> code when the add code is included.
> 

If there are no other comments, I will go ahead and rip out
CONFIG_MEMORY_HOTREMOVE completely, gluing the functionality to
CONFIG_MEMORY_HOTPLUG.

-- 

Thanks,

David / dhildenb