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From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org,
	catalin.marinas@arm.com, will.deacon@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, david@redhat.com,
	cai@lca.pw, logang@deltatee.com, ira.weiny@intel.com
Subject: [PATCH V3 0/4] arm64/mm: Enable memory hot remove
Date: Tue, 14 May 2019 14:30:03 +0530	[thread overview]
Message-ID: <1557824407-19092-1-git-send-email-anshuman.khandual@arm.com> (raw)

This series enables memory hot remove on arm64 after fixing a memblock
removal ordering problem in generic __remove_memory() and kernel page
table race conditions on arm64. This is based on the following arm64
working tree.

git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core

David had pointed out that the following patch is already in next/master
(58b11e136dcc14358) and will conflict with the last patch here. Will fix
the conflict once this series gets reviewed and agreed upon.

Author: David Hildenbrand <david@redhat.com>
Date:   Wed Apr 10 11:02:27 2019 +1000

    mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail

    All callers of arch_remove_memory() ignore errors.  And we should really
    try to remove any errors from the memory removal path.  No more errors are
    reported from __remove_pages().  BUG() in s390x code in case
    arch_remove_memory() is triggered.  We may implement that properly later.
    WARN in case powerpc code failed to remove the section mapping, which is
    better than ignoring the error completely right now.

Testing:

Tested memory hot remove on arm64 for 4K, 16K, 64K page config options with
all possible CONFIG_ARM64_VA_BITS and CONFIG_PGTABLE_LEVELS combinations. But
build tested on non arm64 platforms.

Changes in V3:
 
- Implemented most of the suggestions from Mark Rutland for remove_pagetable()
- Fixed applicable PGTABLE_LEVEL wrappers around pgtable page freeing functions
- Replaced 'direct' with 'sparse_vmap' in remove_pagetable() with inverted polarity
- Changed pointer names ('p' at end) and removed tmp from iterations
- Perform intermediate TLB invalidation while clearing pgtable entries
- Dropped flush_tlb_kernel_range() in remove_pagetable()
- Added flush_tlb_kernel_range() in remove_pte_table() instead
- Renamed page freeing functions for pgtable page and mapped pages
- Used page range size instead of order while freeing mapped or pgtable pages
- Removed all PageReserved() handling while freeing mapped or pgtable pages
- Replaced XXX_index() with XXX_offset() while walking the kernel page table
- Used READ_ONCE() while fetching individual pgtable entries
- Taken overall init_mm.page_table_lock instead of just while changing an entry
- Dropped previously added [pmd|pud]_index() which are not required anymore

- Added a new patch to protect kernel page table race condtion for ptdump
- Added a new patch from Mark Rutland to prevent huge-vmap with ptdump

Changes in V2: (https://lkml.org/lkml/2019/4/14/5)

- Added all received review and ack tags
- Split the series from ZONE_DEVICE enablement for better review
- Moved memblock re-order patch to the front as per Robin Murphy
- Updated commit message on memblock re-order patch per Michal Hocko
- Dropped [pmd|pud]_large() definitions
- Used existing [pmd|pud]_sect() instead of earlier [pmd|pud]_large()
- Removed __meminit and __ref tags as per Oscar Salvador
- Dropped unnecessary 'ret' init in arch_add_memory() per Robin Murphy
- Skipped calling into pgtable_page_dtor() for linear mapping page table
  pages and updated all relevant functions

Changes in V1: (https://lkml.org/lkml/2019/4/3/28)

Anshuman Khandual (3):
  mm/hotplug: Reorder arch_remove_memory() call in __remove_memory()
  arm64/mm: Hold memory hotplug lock while walking for kernel page table dump
  arm64/mm: Enable memory hot remove

Mark Rutland (1):
  arm64/mm: Inhibit huge-vmap with ptdump

 arch/arm64/Kconfig             |   3 +
 arch/arm64/mm/mmu.c            | 215 ++++++++++++++++++++++++++++++++++++++++-
 arch/arm64/mm/ptdump_debugfs.c |   3 +
 mm/memory_hotplug.c            |   3 +-
 4 files changed, 217 insertions(+), 7 deletions(-)

-- 
2.7.4


             reply	other threads:[~2019-05-14  9:00 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-14  9:00 Anshuman Khandual [this message]
2019-05-14  9:00 ` [PATCH V3 1/4] mm/hotplug: Reorder arch_remove_memory() call in __remove_memory() Anshuman Khandual
2019-05-14  9:05   ` David Hildenbrand
2019-05-14  9:00 ` [PATCH V3 2/4] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Anshuman Khandual
2019-05-14  9:16   ` David Hildenbrand
2019-05-14 15:40   ` Mark Rutland
2019-05-15  1:56     ` Anshuman Khandual
2019-05-15 16:58   ` Michal Hocko
2019-05-16 10:23     ` Mark Rutland
2019-05-16 11:05       ` Michal Hocko
2019-05-22 16:42         ` Mark Rutland
2019-05-24  6:06           ` Anshuman Khandual
2019-05-27  7:20           ` Michal Hocko
2019-05-28 14:09             ` Mark Rutland
2019-05-16 11:06       ` Anshuman Khandual
2019-05-16 11:16         ` Michal Hocko
2019-05-23  8:40           ` David Hildenbrand
2019-05-24  5:43             ` Anshuman Khandual
2019-05-14  9:00 ` [PATCH V3 3/4] arm64/mm: Inhibit huge-vmap with ptdump Anshuman Khandual
2019-05-14  9:20   ` David Hildenbrand
2019-05-16  8:38   ` Ard Biesheuvel
2019-05-14  9:00 ` [PATCH V3 4/4] arm64/mm: Enable memory hot remove Anshuman Khandual
2019-05-14  9:08   ` David Hildenbrand
2019-05-15 11:49   ` Mark Rutland
2019-05-16  5:34     ` Anshuman Khandual
2019-05-16 10:57       ` Mark Rutland
2019-05-17  3:15         ` Anshuman Khandual
2019-05-14  9:10 ` [PATCH V3 0/4] " David Hildenbrand

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