From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Logan Gunthorpe <logang@deltatee.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
akpm@linux-foundation.org, will.deacon@arm.com,
catalin.marinas@arm.com
Cc: mhocko@suse.com, mgorman@techsingularity.net,
james.morse@arm.com, mark.rutland@arm.com, robin.murphy@arm.com,
cpandya@codeaurora.org, arunks@codeaurora.org,
dan.j.williams@intel.com, osalvador@suse.de,
pasha.tatashin@oracle.com, david@redhat.com, cai@lca.pw,
Stephen Bates <sbates@raithlin.com>
Subject: Re: [PATCH 2/6] arm64/mm: Enable memory hot remove
Date: Thu, 4 Apr 2019 12:37:58 +0530 [thread overview]
Message-ID: <45afb99f-5785-4048-a748-4e0f06b06b31@arm.com> (raw)
In-Reply-To: <f2ea761c-49b2-88f6-14fa-5aaec57952cb@deltatee.com>
On 04/03/2019 11:02 PM, Logan Gunthorpe wrote:
>
>
> On 2019-04-02 10:30 p.m., Anshuman Khandual wrote:
>> Memory removal from an arch perspective involves tearing down two different
>> kernel based mappings i.e vmemmap and linear while releasing related page
>> table pages allocated for the physical memory range to be removed.
>>
>> Define a common kernel page table tear down helper remove_pagetable() which
>> can be used to unmap given kernel virtual address range. In effect it can
>> tear down both vmemap or kernel linear mappings. This new helper is called
>> from both vmemamp_free() and ___remove_pgd_mapping() during memory removal.
>> The argument 'direct' here identifies kernel linear mappings.
>>
>> Vmemmap mappings page table pages are allocated through sparse mem helper
>> functions like vmemmap_alloc_block() which does not cycle the pages through
>> pgtable_page_ctor() constructs. Hence while removing it skips corresponding
>> destructor construct pgtable_page_dtor().
>>
>> While here update arch_add_mempory() to handle __add_pages() failures by
>> just unmapping recently added kernel linear mapping. Now enable memory hot
>> remove on arm64 platforms by default with ARCH_ENABLE_MEMORY_HOTREMOVE.
>>
>> This implementation is overall inspired from kernel page table tear down
>> procedure on X86 architecture.
>
> I've been working on very similar things for RISC-V. In fact, I'm
> currently in progress on a very similar stripped down version of
> remove_pagetable(). (Though I'm fairly certain I've done a bunch of
> stuff wrong.)
>
> Would it be possible to move this work into common code that can be used
> by all arches? Seems like, to start, we should be able to support both
> arm64 and RISC-V... and maybe even x86 too.
>
> I'd be happy to help integrate and test such functions in RISC-V.
Sure that will be great. The only impediment is pgtable_page_ctor() for kernel
linear mapping. This series is based on current arm64 where linear mapping
pgtable pages go through pgtable_page_ctor() init sequence but that might be
changing soon. If RISC-V does not have pgtable_page_ctor() init for linear
mapping and no other arch specific stuff later on we can try to consolidate
remove_pagetable() atleast for both the architectures.
Then I wondering whether I can transition pud|pmd_large() to pud|pmd_sect().
next prev parent reply other threads:[~2019-04-04 7:08 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 4:30 [PATCH 0/6] arm64/mm: Enable memory hot remove and ZONE_DEVICE Anshuman Khandual
2019-04-03 4:30 ` [PATCH 1/6] arm64/mm: Enable sysfs based memory hot add interface Anshuman Khandual
2019-04-03 8:20 ` David Hildenbrand
2019-04-03 13:12 ` Robin Murphy
2019-04-04 5:21 ` Anshuman Khandual
2019-04-04 5:25 ` Anshuman Khandual
2019-04-04 8:49 ` David Hildenbrand
2019-04-03 4:30 ` [PATCH 2/6] arm64/mm: Enable memory hot remove Anshuman Khandual
2019-04-03 12:37 ` Robin Murphy
2019-04-03 13:15 ` Steven Price
2019-04-04 6:51 ` Anshuman Khandual
2019-04-04 5:39 ` Anshuman Khandual
2019-04-04 11:58 ` Oscar Salvador
2019-04-04 13:03 ` Anshuman Khandual
2019-04-04 15:19 ` Oscar Salvador
2019-04-03 17:32 ` Logan Gunthorpe
2019-04-03 17:57 ` Robin Murphy
2019-04-04 8:23 ` Anshuman Khandual
2019-04-04 7:07 ` Anshuman Khandual [this message]
2019-04-04 9:16 ` Steven Price
2019-04-03 4:30 ` [PATCH 3/6] arm64/mm: Enable struct page allocation from device memory Anshuman Khandual
2019-04-03 4:30 ` [PATCH 4/6] mm/hotplug: Reorder arch_remove_memory() call in __remove_memory() Anshuman Khandual
2019-04-03 8:45 ` Oscar Salvador
2019-04-03 9:17 ` Michal Hocko
2019-04-04 8:32 ` Anshuman Khandual
2019-04-03 9:30 ` David Hildenbrand
2019-04-03 4:30 ` [PATCH 5/6] mm/memremap: Rename and consolidate SECTION_SIZE Anshuman Khandual
2019-04-03 9:26 ` Michal Hocko
2019-04-03 9:30 ` David Hildenbrand
2019-04-03 4:30 ` [PATCH 6/6] arm64/mm: Enable ZONE_DEVICE Anshuman Khandual
2019-04-03 13:58 ` Robin Murphy
2019-04-03 16:07 ` Jerome Glisse
2019-04-04 5:03 ` Anshuman Khandual
2019-04-04 4:42 ` Anshuman Khandual
2019-04-04 5:04 ` Dan Williams
2019-04-04 9:46 ` Robin Murphy
2019-04-07 22:11 ` Dan Williams
2019-04-08 4:03 ` Ira Weiny
2019-04-08 6:03 ` Anshuman Khandual
2019-04-03 18:08 ` [PATCH 0/6] arm64/mm: Enable memory hot remove and ZONE_DEVICE Dan Williams
2019-04-04 13:11 ` Anshuman Khandual
2019-04-04 9:46 ` [RFC 1/2] mm/vmemmap: Enable vmem_altmap based base page mapping for vmemmap Anshuman Khandual
2019-04-04 9:46 ` [RFC 2/2] arm64/mm: Enable ZONE_DEVICE for all page configs Anshuman Khandual
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