mm: add build-time option for hotplug memory default online type

Memory hotplug presently auto-onlines memory into a zone the kernel deems
appropriate if CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y.

The

mm: add build-time option for hotplug memory default online type

Memory hotplug presently auto-onlines memory into a zone the kernel deems
appropriate if CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y.

The memhp_default_state boot param enables runtime config, but it's not
possible to do this at build-time.

Remove CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE, and replace it with
CONFIG_MHP_DEFAULT_ONLINE_TYPE_* choices that sync with the boot param.

Selections:
CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE
=> mhp_default_online_type = "offline"
Memory will not be onlined automatically.

CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO
=> mhp_default_online_type = "online"
Memory will be onlined automatically in a zone deemed.
appropriate by the kernel.

CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL
=> mhp_default_online_type = "online_kernel"
Memory will be onlined automatically.
The zone may allow kernel data (e.g. ZONE_NORMAL).

CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE
=> mhp_default_online_type = "online_movable"
Memory will be onlined automatically.
The zone will be ZONE_MOVABLE.

Default to CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE to match the existing
default CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n behavior.

Existing users of CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y should use
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO.

[[email protected]: update KConfig comments]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Gregory Price <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: WANG Xuerui <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

Document/kexec: generalize crash hotplug description

Commit 79365026f869 ("crash: add a new kexec flag for hotplug support")
generalizes the crash hotplug support to allow architectures to update
mu

Document/kexec: generalize crash hotplug description

Commit 79365026f869 ("crash: add a new kexec flag for hotplug support")
generalizes the crash hotplug support to allow architectures to update
multiple kexec segments on CPU/Memory hotplug and not just elfcorehdr.
Therefore, update the relevant kernel documentation to reflect the same.

No functional change.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sourabh Jain <[email protected]>
Reviewed-by: Petr Tesarik <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Petr Tesarik <[email protected]>
Cc: Sourabh Jain <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/memory-hotplug: fix typo in documentation

I'm 90% sure memory hotunplugging doesn't involve a "fist" phase

Signed-off-by: Amos Wenger <[email protected]>
Reviewed-by: David Hildenbrand <david@re

mm/memory-hotplug: fix typo in documentation

I'm 90% sure memory hotunplugging doesn't involve a "fist" phase

Signed-off-by: Amos Wenger <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

memory-hotplug.rst: fix wrong /sys/device/ path

Actually, it should be /sys/devices/

Signed-off-by: Wang Jinchao <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Signed-o

memory-hotplug.rst: fix wrong /sys/device/ path

Actually, it should be /sys/devices/

Signed-off-by: Wang Jinchao <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>
Message-ID: <ZQz1NUATBMOb3RT+@fedora>

show more ...

Documentation: Drop or replace remaining mentions of IA64

Drop or update mentions of IA64, as appropriate.

Signed-off-by: Ard Biesheuvel <[email protected]>

crash: memory and CPU hotplug sysfs attributes

Introduce the crash_hotplug attribute for memory and CPUs for use by
userspace. These attributes directly facilitate the udev rule for
managing usersp

crash: memory and CPU hotplug sysfs attributes

Introduce the crash_hotplug attribute for memory and CPUs for use by
userspace. These attributes directly facilitate the udev rule for
managing userspace re-loading of the crash kernel upon hot un/plug
changes.

For memory, expose the crash_hotplug attribute to the
/sys/devices/system/memory directory. For example:

# udevadm info --attribute-walk /sys/devices/system/memory/memory81
looking at device '/devices/system/memory/memory81':
KERNEL=="memory81"
SUBSYSTEM=="memory"
DRIVER==""
ATTR{online}=="1"
ATTR{phys_device}=="0"
ATTR{phys_index}=="00000051"
ATTR{removable}=="1"
ATTR{state}=="online"
ATTR{valid_zones}=="Movable"

looking at parent device '/devices/system/memory':
KERNELS=="memory"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{auto_online_blocks}=="offline"
ATTRS{block_size_bytes}=="8000000"
ATTRS{crash_hotplug}=="1"

For CPUs, expose the crash_hotplug attribute to the
/sys/devices/system/cpu directory. For example:

# udevadm info --attribute-walk /sys/devices/system/cpu/cpu0
looking at device '/devices/system/cpu/cpu0':
KERNEL=="cpu0"
SUBSYSTEM=="cpu"
DRIVER=="processor"
ATTR{crash_notes}=="277c38600"
ATTR{crash_notes_size}=="368"
ATTR{online}=="1"

looking at parent device '/devices/system/cpu':
KERNELS=="cpu"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{crash_hotplug}=="1"
ATTRS{isolated}==""
ATTRS{kernel_max}=="8191"
ATTRS{nohz_full}==" (null)"
ATTRS{offline}=="4-7"
ATTRS{online}=="0-3"
ATTRS{possible}=="0-7"
ATTRS{present}=="0-3"

With these sysfs attributes in place, it is possible to efficiently
instruct the udev rule to skip crash kernel reloading for kernels
configured with crash hotplug support.

For example, the following is the proposed udev rule change for RHEL
system 98-kexec.rules (as the first lines of the rule file):

# The kernel updates the crash elfcorehdr for CPU and memory changes
SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
SUBSYSTEM=="memory", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"

When examined in the context of 98-kexec.rules, the above rules test if
crash_hotplug is set, and if so, the userspace initiated
unload-then-reload of the crash kernel is skipped.

CPU and memory checks are separated in accordance with CONFIG_HOTPLUG_CPU
and CONFIG_MEMORY_HOTPLUG kernel config options. If an architecture
supports, for example, memory hotplug but not CPU hotplug, then the
/sys/devices/system/memory/crash_hotplug attribute file is present, but
the /sys/devices/system/cpu/crash_hotplug attribute file will NOT be
present. Thus the udev rule skips userspace processing of memory hot
un/plug events, but the udev rule will evaluate false for CPU events, thus
allowing userspace to process CPU hot un/plug events (ie the
unload-then-reload of the kdump capture kernel).

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Eric DeVolder <[email protected]>
Reviewed-by: Sourabh Jain <[email protected]>
Acked-by: Hari Bathini <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Akhil Raj <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Young <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Mimi Zohar <[email protected]>
Cc: Naveen N. Rao <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Thomas Weißschuh <[email protected]>
Cc: Valentin Schneider <[email protected]>
Cc: Vivek Goyal <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/memory_hotplug: support memmap_on_memory when memmap is not aligned to pageblocks

Currently, memmap_on_memory feature is only supported with memory block
sizes that result in vmemmap pages coveri

mm/memory_hotplug: support memmap_on_memory when memmap is not aligned to pageblocks

Currently, memmap_on_memory feature is only supported with memory block
sizes that result in vmemmap pages covering full page blocks. This is
because memory onlining/offlining code requires applicable ranges to be
pageblock-aligned, for example, to set the migratetypes properly.

This patch helps to lift that restriction by reserving more pages than
required for vmemmap space. This helps the start address to be page block
aligned with different memory block sizes. Using this facility implies
the kernel will be reserving some pages for every memoryblock. This
allows the memmap on memory feature to be widely useful with different
memory block size values.

For ex: with 64K page size and 256MiB memory block size, we require 4
pages to map vmemmap pages, To align things correctly we end up adding a
reserve of 28 pages. ie, for every 4096 pages 28 pages get reserved.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Vishal Verma <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/memory_hotplug: document the signal_pending() check in offline_pages()

Let's update the documentation that any signal is sufficient, and add a
comment that not only checking for fatal signals is

mm/memory_hotplug: document the signal_pending() check in offline_pages()

Let's update the documentation that any signal is sufficient, and add a
comment that not only checking for fatal signals is historical baggage:
changing it now could break existing user space. although unlikely.

For example, when an app provides a custom SIGALRM handler and triggers
memory offlining, the timeout cmd would no longer stop memory offlining,
because SIGALRM would no longer be considered a fatal signal.

Note that using signal_pending() instead of fatal_signal_pending() is
an anti-pattern, but slowly deprecating that behavior to eventually
change it in the far future is probably not worth the effort. If this
ever becomes relevant for user-space, we might want to rethink.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

docs/admin-guide/mm: remove useless markup

It is enough to use a file name to cross-reference another rst document.

Jon says:
The right things will happen in the HTML output, readers of the
pla

docs/admin-guide/mm: remove useless markup

It is enough to use a file name to cross-reference another rst document.

Jon says:
The right things will happen in the HTML output, readers of the
plain-text will know immediately where to go, and we don't have to add
the label clutter.

Drop reference markup and unnecessary labels and use plain file names.

Signed-off-by: Mike Rapoport (IBM) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Corbet <[email protected]>

show more ...

mm: hugetlb_vmemmap: introduce the name HVO

It it inconvenient to mention the feature of optimizing vmemmap pages
associated with HugeTLB pages when communicating with others since there
is no speci

mm: hugetlb_vmemmap: introduce the name HVO

It it inconvenient to mention the feature of optimizing vmemmap pages
associated with HugeTLB pages when communicating with others since there
is no specific or abbreviated name for it when it is first introduced.
Let us give it a name HVO (HugeTLB Vmemmap Optimization) from now.

This commit also updates the document about "hugetlb_free_vmemmap" by the
way discussed in thread [1].

Link: https://lore.kernel.org/all/[email protected]/ [1]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

memory-hotplug.rst: document the "auto-movable" online policy

Commit e83a437faa62 ("mm/memory_hotplug: introduce "auto-movable" online
policy") introduced a new memory online policy to automatically

memory-hotplug.rst: document the "auto-movable" online policy

Commit e83a437faa62 ("mm/memory_hotplug: introduce "auto-movable" online
policy") introduced a new memory online policy to automatically select a
zone for memory blocks to be onlined. It added a way to set the active
online policy and tunables for the auto-movable online policy.

Follow-up commits tweaked the "auto-movable" policy to also consider
memory device details when selecting zones for memory blocks to be
onlined.

Let's document the new toggles and how the two online policies we have
work.

[[email protected]: updates]
Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: fix wrong /sys/module/memory_hotplug/parameters/ path

We accidentially added a superfluous "s".

Link: https://lkml.kernel.org/r/[email protected]
Fixes: ac

memory-hotplug.rst: fix wrong /sys/module/memory_hotplug/parameters/ path

We accidentially added a superfluous "s".

Link: https://lkml.kernel.org/r/[email protected]
Fixes: ac3332c44767 ("memory-hotplug.rst: complete admin-guide overhaul")
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: fix two instances of "movablecore" that should be "movable_node"

Patch series "memory-hotplug.rst: document the "auto-movable" online
policy".

Now that the memory-hotplug.rst ov

memory-hotplug.rst: fix two instances of "movablecore" that should be "movable_node"

Patch series "memory-hotplug.rst: document the "auto-movable" online
policy".

Now that the memory-hotplug.rst overhaul is upstream, proper
documentation for the "auto-movable" online policy, documenting all new
toggles and options. Along, two fixes for the original overhaul.

This patch (of 3):

We really want to refer to the "movable_node" kernel command line
parameter here.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: ac3332c44767 ("memory-hotplug.rst: complete admin-guide overhaul")
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: complete admin-guide overhaul

The memory hot(un)plug documentation is outdated and incomplete. Most of
the content dates back to 2007, so it's time for a major overhaul.

Let's

memory-hotplug.rst: complete admin-guide overhaul

The memory hot(un)plug documentation is outdated and incomplete. Most of
the content dates back to 2007, so it's time for a major overhaul.

Let's rewrite, reorganize and update most parts of the documentation. In
addition to memory hot(un)plug, also add some details regarding
ZONE_MOVABLE, with memory hotunplug being one of its main consumers.

Drop the file history, that information can more reliably be had from the
git log.

The style of the document is also properly fixed that e.g., "restview"
renders it cleanly now.

In the future, we might add some more details about virt users like
virtio-mem, the XEN balloon, the Hyper-V balloon and ppc64 dlpar.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Mike Rapoport <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Stephen Rothwell <[email protected]>

Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: remove locking details from admin-guide

Patch series "memory-hotplug.rst: complete admin-guide overhaul", v3.

This patch (of 2):

We have the same content at Documentation/core-

memory-hotplug.rst: remove locking details from admin-guide

Patch series "memory-hotplug.rst: complete admin-guide overhaul", v3.

This patch (of 2):

We have the same content at Documentation/core-api/memory-hotplug.rst and
it doesn't fit into the admin-guide. The documentation was accidentially
duplicated when merging.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Mike Rapoport <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page

When we free a HugeTLB page to the buddy allocator, we need to allocate
the vmemmap pages associated with it. However, we may

mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page

When we free a HugeTLB page to the buddy allocator, we need to allocate
the vmemmap pages associated with it. However, we may not be able to
allocate the vmemmap pages when the system is under memory pressure. In
this case, we just refuse to free the HugeTLB page. This changes behavior
in some corner cases as listed below:

1) Failing to free a huge page triggered by the user (decrease nr_pages).

User needs to try again later.

2) Failing to free a surplus huge page when freed by the application.

Try again later when freeing a huge page next time.

3) Failing to dissolve a free huge page on ZONE_MOVABLE via
offline_pages().

This can happen when we have plenty of ZONE_MOVABLE memory, but
not enough kernel memory to allocate vmemmmap pages. We may even
be able to migrate huge page contents, but will not be able to
dissolve the source huge page. This will prevent an offline
operation and is unfortunate as memory offlining is expected to
succeed on movable zones. Users that depend on memory hotplug
to succeed for movable zones should carefully consider whether the
memory savings gained from this feature are worth the risk of
possibly not being able to offline memory in certain situations.

4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via
alloc_contig_range() - once we have that handling in place. Mainly
affects CMA and virtio-mem.

Similar to 3). virito-mem will handle migration errors gracefully.
CMA might be able to fallback on other free areas within the CMA
region.

Vmemmap pages are allocated from the page freeing context. In order for
those allocations to be not disruptive (e.g. trigger oom killer)
__GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because
a non sleeping allocation would be too fragile and it could fail too
easily under memory pressure. GFP_ATOMIC or other modes to access memory
reserves is not used because we want to prevent consuming reserves under
heavy hugetlb freeing.

[[email protected]: fix dissolve_free_huge_page use of tail/head page]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix alloc_vmemmap_page_list documentation warning]
Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Signed-off-by: Mike Kravetz <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Barry Song <[email protected]>
Cc: Bodeddula Balasubramaniam <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Chen Huang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: HORIGUCHI NAOYA <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Oliver Neukum <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Pawan Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning

Document the special handling of page pinning when ZONE_MOVABLE present.

Link: https://lkml.kernel.org/r/20210215161349.246722-11-

memory-hotplug.rst: add a note about ZONE_MOVABLE and page pinning

Document the special handling of page pinning when ZONE_MOVABLE present.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Pavel Tatashin <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Tyler Hicks <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

Documentation: sysfs/memory: clarify some memory block device properties

In commit 53cdc1cb29e8 ("drivers/base/memory.c: indicate all memory blocks
as removable") we changed the output of the "remov

Documentation: sysfs/memory: clarify some memory block device properties

In commit 53cdc1cb29e8 ("drivers/base/memory.c: indicate all memory blocks
as removable") we changed the output of the "removable" property of memory
devices to return "1" if and only if the kernel supports memory offlining.

Let's update documentation, stating that the interface is legacy. Also
update documentation of the "state" property and "valid_zones" properties.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

drivers/base/memory: don't store phys_device in memory blocks

No need to store the value for each and every memory block, as we can
easily query the value at runtime. Reshuffle the members to optim

drivers/base/memory: don't store phys_device in memory blocks

No need to store the value for each and every memory block, as we can
easily query the value at runtime. Reshuffle the members to optimize the
memory layout. Also, let's clarify what the interface once was used for
and why it's legacy nowadays.

"phys_device" was used on s390x in older versions of lsmem[2]/chmem[3],
back when they were still part of s390x-tools. They were later replaced
by the variants in linux-utils. For example, RHEL6 and RHEL7 contain
lsmem/chmem from s390-utils. RHEL8 switched to versions from util-linux
on s390x [4].

"phys_device" was added with sysfs support for memory hotplug in commit
3947be1969a9 ("[PATCH] memory hotplug: sysfs and add/remove functions") in
2005. It always returned 0.

s390x started returning something != 0 on some setups (if sclp.rzm is set
by HW) in 2010 via commit 57b552ba0b2f ("memory hotplug/s390: set
phys_device").

For s390x, it allowed for identifying which memory block devices belong to
the same storage increment (RZM). Only if all memory block devices
comprising a single storage increment were offline, the memory could
actually be removed in the hypervisor.

Since commit e5d709bb5fb7 ("s390/memory hotplug: provide
memory_block_size_bytes() function") in 2013 a memory block device spans
at least one storage increment - which is why the interface isn't really
helpful/used anymore (except by old lsmem/chmem tools).

There were once RFC patches to make use of "phys_device" in ACPI context;
however, the underlying problem could be solved using different interfaces
[1].

[1] https://patchwork.kernel.org/patch/2163871/
[2] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/lsmem
[3] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/chmem
[4] https://bugzilla.redhat.com/show_bug.cgi?id=1504134

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Gerald Schaefer <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Vaibhav Jain <[email protected]>
Cc: Tom Rix <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

memory-hotplug.rst: add some details about locking internals

Let's document the magic a bit, especially why device_hotplug_lock is
required when adding/removing memory and how it all play together w

memory-hotplug.rst: add some details about locking internals

Let's document the magic a bit, especially why device_hotplug_lock is
required when adding/removing memory and how it all play together with
requests to online/offline memory from user space.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Reviewed-by: Rashmica Gupta <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: John Allen <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Mathieu Malaterre <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Nathan Fontenot <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: YASUAKI ISHIMATSU <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

docs/admin-guide: memory-hotplug: remove table of contents

Remove "manual" table of contents and leave only the ReST tag so that
Sphinx will take care of TOC generation.

Signed-off-by: Mike Rapopor

docs/admin-guide: memory-hotplug: remove table of contents

Remove "manual" table of contents and leave only the ReST tag so that
Sphinx will take care of TOC generation.

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>

show more ...

docs/vm: split memory hotplug notifier description to Documentation/core-api

The memory hotplug notifier description is about kernel internals rather
than admin/user visible API. Place it appropriat

docs/vm: split memory hotplug notifier description to Documentation/core-api

The memory hotplug notifier description is about kernel internals rather
than admin/user visible API. Place it appropriately.

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>

show more ...

docs: move memory hotplug description into admin-guide/mm

The memory hotplug description in Documentation/memory-hotplug.txt is
already formatted as ReST and can be easily added to admin-guide/mm
se

docs: move memory hotplug description into admin-guide/mm

The memory hotplug description in Documentation/memory-hotplug.txt is
already formatted as ReST and can be easily added to admin-guide/mm
section.

While on it, slightly update formatting to make it consistent with the
doc-guide.

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>

show more ...