linux-kernel - [PATCH RFC 0/3] mm/memory_hotplug: Factor out memory block device handling

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Date:   Mon,  8 Apr 2019 12:12:23 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Banman <andrew.banman@....com>, mike.travis@....com,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pavel.tatashin@...rosoft.com>,
        Wei Yang <richard.weiyang@...il.com>, Qian Cai <cai@....pw>,
        Arun KS <arunks@...eaurora.org>,
        Mathieu Malaterre <malat@...ian.org>, linux-mm@...ck.org,
        dan.j.williams@...el.com, David Hildenbrand <david@...hat.com>
Subject: [PATCH RFC 0/3] mm/memory_hotplug: Factor out memory block device handling

We only want memory block devices for memory to be onlined/offlined
(add/remove from the buddy). This is required so user space can
online/offline memory and kdump gets notified about newly onlined memory.

Only such memory has the requirement of having to span whole memory blocks.
Let's factor out creation/removal of memory block devices.

This not only allows to clean up arch_add_memory() to get rid of
want_memblock, but also reduces locking overhead and eventually allows
us to handle errors while adding memory in a nicer fashion.

Only did a quick sanity test with DIMM plug/unplug. This should be
sufficient to discuss the general approach. Patches are against
next/master.

David Hildenbrand (3):
  mm/memory_hotplug: Simplify and fix check_hotplug_memory_range()
  mm/memory_hotplug: Create memory block devices after arch_add_memory()
  mm/memory_hotplug: Remove memory block devices before
    arch_remove_memory()

 drivers/base/memory.c  | 108 +++++++++++++++++++++--------------------
 drivers/base/node.c    |   7 ++-
 include/linux/memory.h |   4 +-
 include/linux/node.h   |   6 +--
 mm/memory_hotplug.c    |  38 +++++++--------
 5 files changed, 81 insertions(+), 82 deletions(-)

-- 
2.17.2