Seems we all agree that information about SECTION, e.g. section size,
sections per memory block should be kept as kernel internals, and not
exposed to userspace.
This patch updates Documentation/memory-hotplug.txt to refer to memory
blocks instead of memory sections where appropriate and added a
paragraph to explain that memory blocks are made of memory sections.
The documentation update is mostly provided by Nathan.
Also, as end_phys_index in code is actually not the end section id, but
the end memory block id, which should always be the same as phys_index.
So it is removed here.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull trivial tree from Jiri Kosina:
"The usual trivial updates all over the tree -- mostly typo fixes and
documentation updates"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (52 commits)
doc: Documentation/cputopology.txt fix typo
treewide: Convert retrun typos to return
Fix comment typo for init_cma_reserved_pageblock
Documentation/trace: Correcting and extending tracepoint documentation
mm/hotplug: fix a typo in Documentation/memory-hotplug.txt
power: Documentation: Update s2ram link
doc: fix a typo in Documentation/00-INDEX
Documentation/printk-formats.txt: No casts needed for u64/s64
doc: Fix typo "is is" in Documentations
treewide: Fix printks with 0x%#
zram: doc fixes
Documentation/kmemcheck: update kmemcheck documentation
doc: documentation/hwspinlock.txt fix typo
PM / Hibernate: add section for resume options
doc: filesystems : Fix typo in Documentations/filesystems
scsi/megaraid fixed several typos in comments
ppc: init_32: Fix error typo "CONFIG_START_KERNEL"
treewide: Add __GFP_NOWARN to k.alloc calls with v.alloc fallbacks
page_isolation: Fix a comment typo in test_pages_isolated()
doc: fix a typo about irq affinity
...
CONFIG_ARCH_MEMORY_PROBE enables the
/sys/devices/system/memory/probe interface, which allows a given
memory address to be hot-added as follows:
# echo start_address_of_new_memory > /sys/devices/system/memory/probe
(See Documentation/memory-hotplug.txt for more details.)
This probe interface is required on powerpc. On x86, however,
ACPI notifies a memory hotplug event to the kernel, which
performs its hotplug operation as the result.
Therefore, regular users do not need this interface on x86. This probe
interface is also error-prone and misleading that the kernel blindly
adds a given memory address without checking if the memory is present
on the system; no probing is done despite of its name.
The kernel crashes when a user requests to online a memory block
that is not present on the system. This interface is currently
used for testing as it can fake a hotplug event.
This patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86,
adds its Kconfig menu entry on x86, and clarifies its use in
Documentation/ memory-hotplug.txt.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: linux-mm@kvack.org
Cc: dave@sr71.net
Cc: isimatu.yasuaki@jp.fujitsu.com
Cc: tangchen@cn.fujitsu.com
Cc: vasilis.liaskovitis@profitbricks.com
Link: http://lkml.kernel.org/r/1374256068-26016-1-git-send-email-toshi.kani@hp.com
[ Edited it slightly. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add online_movable and online_kernel for logic memory hotplug. This is
the dynamic version of "movablecore" & "kernelcore".
We have the same reason to introduce it as to introduce "movablecore" &
"kernelcore". It has the same motive as "movablecore" & "kernelcore", but
it is dynamic/running-time:
o We can configure memory as kernelcore or movablecore after boot.
Userspace workload is increased, we need more hugepage, we can't use
"online_movable" to add memory and allow the system use more
THP(transparent-huge-page), vice-verse when kernel workload is increase.
Also help for virtualization to dynamic configure host/guest's memory,
to save/(reduce waste) memory.
Memory capacity on Demand
o When a new node is physically online after boot, we need to use
"online_movable" or "online_kernel" to configure/portion it as we
expected when we logic-online it.
This configuration also helps for physically-memory-migrate.
o all benefit as the same as existed "movablecore" & "kernelcore".
o Preparing for movable-node, which is very important for power-saving,
hardware partitioning and high-available-system(hardware fault
management).
(Note, we don't introduce movable-node here.)
Action behavior:
When a memoryblock/memorysection is onlined by "online_movable", the kernel
will not have directly reference to the page of the memoryblock,
thus we can remove that memory any time when needed.
When it is online by "online_kernel", the kernel can use it.
When it is online by "online", the zone type doesn't changed.
Current constraints:
Only the memoryblock which is adjacent to the ZONE_MOVABLE
can be online from ZONE_NORMAL to ZONE_MOVABLE.
[akpm@linux-foundation.org: use min_t, cleanups]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently memory_hotplug only manages the node_states[N_HIGH_MEMORY], it
forgets to manage node_states[N_NORMAL_MEMORY]. This may cause
node_states[N_NORMAL_MEMORY] to become incorrect.
Example, if a node is empty before online, and we online a memory which is
in ZONE_NORMAL. And after online, node_states[N_HIGH_MEMORY] is correct,
but node_states[N_NORMAL_MEMORY] is incorrect, the online code doesn't set
the new online node to node_states[N_NORMAL_MEMORY].
The same thing will happen when offlining (the offline code doesn't clear
the node from node_states[N_NORMAL_MEMORY] when needed). Some memory
managment code depends node_states[N_NORMAL_MEMORY], so we have to fix up
the node_states[N_NORMAL_MEMORY].
We add node_states_check_changes_online() and
node_states_check_changes_offline() to detect whether
node_states[N_HIGH_MEMORY] and node_states[N_NORMAL_MEMORY] are changed
while hotpluging.
Also add @status_change_nid_normal to struct memory_notify, thus the
memory hotplug callbacks know whether the node_states[N_NORMAL_MEMORY] are
changed. (We can add a @flags and reuse @status_change_nid instead of
introducing @status_change_nid_normal, but it will add much more
complexity in memory hotplug callback in every subsystem. So introducing
@status_change_nid_normal is better and it doesn't change the sematics of
@status_change_nid)
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Rob Landley <rob@landley.net>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Update the memory sysfs code such that each sysfs memory directory is now
considered a memory block that can span multiple memory sections per
memory block. The default size of each memory block is SECTION_SIZE_BITS
to maintain the current behavior of having a single memory section per
memory block (i.e. one sysfs directory per memory section).
For architectures that want to have memory blocks span multiple
memory sections they need only define their own memory_block_size_bytes()
routine.
Update the memory hotplug documentation to reflect the new behaviors of
memory blocks reflected in sysfs.
Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Reviewed-by: Robin Holt <holt@sgi.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Commit c04fc586c (mm: show node to memory section relationship with
symlinks in sysfs) created symlinks from nodes to memory sections, e.g.
/sys/devices/system/node/node1/memory135 -> ../../memory/memory135
If you're examining the memory section though and are wondering what node
it might belong to, you can find it by grovelling around in sysfs, but
it's a little cumbersome.
Add a reverse symlink for each memory section that points back to the
node to which it belongs.
Signed-off-by: Alex Chiang <achiang@hp.com>
Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Show node to memory section relationship with symlinks in sysfs
Add /sys/devices/system/node/nodeX/memoryY symlinks for all
the memory sections located on nodeX. For example:
/sys/devices/system/node/node1/memory135 -> ../../memory/memory135
indicates that memory section 135 resides on node1.
Also revises documentation to cover this change as well as updating
Documentation/ABI/testing/sysfs-devices-memory to include descriptions
of memory hotremove files 'phys_device', 'phys_index', and 'state'
that were previously not described there.
In addition to it always being a good policy to provide users with
the maximum possible amount of physical location information for
resources that can be hot-added and/or hot-removed, the following
are some (but likely not all) of the user benefits provided by
this change.
Immediate:
- Provides information needed to determine the specific node
on which a defective DIMM is located. This will reduce system
downtime when the node or defective DIMM is swapped out.
- Prevents unintended onlining of a memory section that was
previously offlined due to a defective DIMM. This could happen
during node hot-add when the user or node hot-add assist script
onlines _all_ offlined sections due to user or script inability
to identify the specific memory sections located on the hot-added
node. The consequences of reintroducing the defective memory
could be ugly.
- Provides information needed to vary the amount and distribution
of memory on specific nodes for testing or debugging purposes.
Future:
- Will provide information needed to identify the memory
sections that need to be offlined prior to physical removal
of a specific node.
Symlink creation during boot was tested on 2-node x86_64, 2-node
ppc64, and 2-node ia64 systems. Symlink creation during physical
memory hot-add tested on a 2-node x86_64 system.
Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is add a document for memory hotplug to describe "How to use" and
"Current status".
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
