Changes in sysfs-devices-memory

c91c6062 - Document/kexec: generalize crash hotplug description

Mon, 12 Aug 2024 04:16:51 +0000

Document/kexec: generalize crash hotplug descriptionCommit 79365026f869 ("crash: add a new kexec flag for hotplug support")generalizes the crash hotplug support to allow architectures to updatemultiple 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/20240812041651.703156-1-sourabhjain@linux.ibm.comSigned-off-by: Sourabh Jain Reviewed-by: Petr Tesarik Acked-by: Baoquan He Cc: Hari Bathini Cc: Petr Tesarik Cc: Sourabh Jain Cc: Jonathan Corbet Signed-off-by: Andrew Morton List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

88a6f899 - crash: memory and CPU hotplug sysfs attributes

Mon, 14 Aug 2023 21:44:42 +0000

crash: memory and CPU hotplug sysfs attributesIntroduce the crash_hotplug attribute for memory and CPUs for use byuserspace. These attributes directly facilitate the udev rule formanaging userspace re-loading of the crash kernel upon hot un/plugchanges.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 efficientlyinstruct the udev rule to skip crash kernel reloading for kernelsconfigured with crash hotplug support.For example, the following is the proposed udev rule change for RHELsystem 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 ifcrash_hotplug is set, and if so, the userspace initiatedunload-then-reload of the crash kernel is skipped.CPU and memory checks are separated in accordance with CONFIG_HOTPLUG_CPUand CONFIG_MEMORY_HOTPLUG kernel config options. If an architecturesupports, for example, memory hotplug but not CPU hotplug, then the/sys/devices/system/memory/crash_hotplug attribute file is present, butthe /sys/devices/system/cpu/crash_hotplug attribute file will NOT bepresent. Thus the udev rule skips userspace processing of memory hotun/plug events, but the udev rule will evaluate false for CPU events, thusallowing userspace to process CPU hot un/plug events (ie theunload-then-reload of the kdump capture kernel).Link: https://lkml.kernel.org/r/20230814214446.6659-5-eric.devolder@oracle.comSigned-off-by: Eric DeVolder Reviewed-by: Sourabh Jain Acked-by: Hari Bathini Acked-by: Baoquan He Cc: Akhil Raj Cc: Bjorn Helgaas Cc: Borislav Petkov (AMD) Cc: Boris Ostrovsky Cc: Dave Hansen Cc: Dave Young Cc: David Hildenbrand Cc: Eric W. Biederman Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Konrad Rzeszutek Wilk Cc: Mimi Zohar Cc: Naveen N. Rao Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Sean Christopherson Cc: Takashi Iwai Cc: Thomas Gleixner Cc: Thomas Weißschuh Cc: Valentin Schneider Cc: Vivek Goyal Cc: Vlastimil Babka Signed-off-by: Andrew Morton List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

a89107c0 - Documentation: sysfs/memory: clarify some memory block device properties

Fri, 26 Feb 2021 01:17:28 +0000

Documentation: sysfs/memory: clarify some memory block device propertiesIn commit 53cdc1cb29e8 ("drivers/base/memory.c: indicate all memory blocksas removable") we changed the output of the "removable" property of memorydevices to return "1" if and only if the kernel supports memory offlining.Let's update documentation, stating that the interface is legacy. Alsoupdate documentation of the "state" property and "valid_zones" properties.Link: https://lkml.kernel.org/r/20210201181347.13262-3-david@redhat.comSigned-off-by: David Hildenbrand Acked-by: Michal Hocko Reviewed-by: Oscar Salvador Cc: Dave Hansen Cc: Jonathan Corbet Cc: David Hildenbrand Cc: Greg Kroah-Hartman Cc: Jonathan Cameron Cc: Ilya Dryomov Cc: Mauro Carvalho Chehab Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

e9a2e48e - drivers/base/memory: don't store phys_device in memory blocks

Fri, 26 Feb 2021 01:17:24 +0000

drivers/base/memory: don't store phys_device in memory blocksNo need to store the value for each and every memory block, as we caneasily query the value at runtime. Reshuffle the members to optimize thememory layout. Also, let's clarify what the interface once was used forand 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 replacedby the variants in linux-utils. For example, RHEL6 and RHEL7 containlsmem/chmem from s390-utils. RHEL8 switched to versions from util-linuxon s390x [4]."phys_device" was added with sysfs support for memory hotplug in commit3947be1969a9 ("[PATCH] memory hotplug: sysfs and add/remove functions") in2005. It always returned 0.s390x started returning something != 0 on some setups (if sclp.rzm is setby HW) in 2010 via commit 57b552ba0b2f ("memory hotplug/s390: setphys_device").For s390x, it allowed for identifying which memory block devices belong tothe same storage increment (RZM). Only if all memory block devicescomprising a single storage increment were offline, the memory couldactually be removed in the hypervisor.Since commit e5d709bb5fb7 ("s390/memory hotplug: providememory_block_size_bytes() function") in 2013 a memory block device spansat least one storage increment - which is why the interface isn't reallyhelpful/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=1504134Link: https://lkml.kernel.org/r/20210201181347.13262-2-david@redhat.comSigned-off-by: David Hildenbrand Acked-by: Michal Hocko Reviewed-by: Oscar Salvador Cc: Dave Hansen Cc: Greg Kroah-Hartman Cc: Gerald Schaefer Cc: Jonathan Corbet Cc: "Rafael J. Wysocki" Cc: Mauro Carvalho Chehab Cc: Ilya Dryomov Cc: Vaibhav Jain Cc: Tom Rix Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

4ec0b092 - docs: ABI: Drop trailing whitespace

Tue, 10 Nov 2020 14:40:33 +0000

docs: ABI: Drop trailing whitespaceRemove all trailing whitespace from the ABI documentation.Most of it was introduced during recent updates.Signed-off-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20201110144033.3278499-1-geert+renesas@glider.beSigned-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

54a19b4d - docs: ABI: cleanup several ABI documents

Fri, 30 Oct 2020 07:40:50 +0000

docs: ABI: cleanup several ABI documentsThere are some ABI documents that, while they don't generateany warnings, they have issues when parsed by get_abi.pl scripton its output result.Address them, in order to provide a clean output.Reviewed-by: Tom Rix # for fpga-managerReviewed-By: Kajol Jain # for sysfs-bus-event_source-devices-hv_gpci and sysfs-bus-event_source-devices-hv_24x7Acked-by: Jonathan Cameron #for IIOAcked-by: Oded Gabbay # for HabanalabsAcked-by: Vaibhav Jain # for sysfs-bus-papr-pmemAcked-by: Cezary Rojewski # for catptAcked-by: Suzuki K Poulose Acked-by: Ilya Dryomov # for rbdAcked-by: Jonathan Corbet Signed-off-by: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/5bc78e5b68ed1e9e39135173857cb2e753be868f.1604042072.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

ed2f2400 - memory-hotplug: add sysfs valid_zones attribute

Thu, 09 Oct 2014 22:26:31 +0000

memory-hotplug: add sysfs valid_zones attributeCurrently memory-hotplug has two limits:1. If the memory block is in ZONE_NORMAL, you can change it to ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.2. If the memory block is in ZONE_MOVABLE, you can change it to ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.With this patch, we can easy to know a memory block can be onlined towhich zone, and don't need to know the above two limits.Updated the related Documentation.[akpm@linux-foundation.org: use conventional comment layout][akpm@linux-foundation.org: fix build with CONFIG_MEMORY_HOTREMOVE=n][akpm@linux-foundation.org: remove unused local zone_prev]Signed-off-by: Zhang Zhen Cc: Dave Hansen Cc: David Rientjes Cc: Toshi Kani Cc: Yasuaki Ishimatsu Cc: Naoya Horiguchi Cc: Wang Nan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

0ea6e611 - Documentation: update broken web addresses.

Sat, 24 Jul 2010 03:51:24 +0000

Documentation: update broken web addresses.Below you will find an updated version from the original series bunching all patches into one big patchupdating broken web addresses that are located in Documentation/*Some of the addresses date as far far back as 1995 etc... so searching became a bit difficult,the best way to deal with these is to use web.archive.org to locate these addresses that are outdated.Now there are also some addresses pointing to .spec files some are located, but some(after searchingon the companies site)where still no where to be found. In this case I just changed the addressto the company site this way the users can contact the company and they can locate them for the users.Signed-off-by: Justin P. Mattock Signed-off-by: Thomas Weber Signed-off-by: Mike Frysinger Cc: Paulo Marques Cc: Randy Dunlap Cc: Michael Neuling Signed-off-by: Jiri Kosina List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

a33f3224 - Documentation/: it's -> its where appropriate

Thu, 22 Apr 2010 22:08:02 +0000

Documentation/: it's -> its where appropriateFix obvious cases of "it's" being used when "its" was meant.Signed-off-by: Francis Galiegue Acked-by: Randy Dunlap Signed-off-by: Jiri Kosina List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

dee5d0d5 - mm: add numa node symlink for memory section in sysfs

Tue, 15 Dec 2009 01:59:05 +0000

mm: add numa node symlink for memory section in sysfsCommit c04fc586c (mm: show node to memory section relationship withsymlinks in sysfs) created symlinks from nodes to memory sections, e.g./sys/devices/system/node/node1/memory135 -> ../../memory/memory135If you're examining the memory section though and are wondering what nodeit might belong to, you can find it by grovelling around in sysfs, butit's a little cumbersome.Add a reverse symlink for each memory section that points back to thenode to which it belongs.Signed-off-by: Alex Chiang Cc: Gary Hade Cc: Badari Pulavarty Cc: Ingo Molnar Acked-by: David Rientjes Cc: Greg KH Cc: Randy Dunlap Cc: David Rientjes Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

c04fc586 - mm: show node to memory section relationship with symlinks in sysfs

Tue, 06 Jan 2009 22:39:14 +0000

mm: show node to memory section relationship with symlinks in sysfsShow node to memory section relationship with symlinks in sysfsAdd /sys/devices/system/node/nodeX/memoryY symlinks for allthe memory sections located on nodeX. For example:/sys/devices/system/node/node1/memory135 -> ../../memory/memory135indicates that memory section 135 resides on node1.Also revises documentation to cover this change as well as updatingDocumentation/ABI/testing/sysfs-devices-memory to include descriptionsof 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 withthe maximum possible amount of physical location information forresources that can be hot-added and/or hot-removed, the followingare some (but likely not all) of the user benefits provided bythis 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-nodeppc64, and 2-node ia64 systems. Symlink creation during physicalmemory hot-add tested on a 2-node x86_64 system.Signed-off-by: Gary Hade Signed-off-by: Badari Pulavarty Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory

5c755e9f - memory-hotplug: add sysfs removable attribute for hotplug memory remove

Thu, 24 Jul 2008 04:28:19 +0000

memory-hotplug: add sysfs removable attribute for hotplug memory removeMemory may be hot-removed on a per-memory-block basis, particularly onPOWER where the SPARSEMEM section size often matches the memory-blocksize. A user-level agent must be able to identify which sections ofmemory are likely to be removable before attempting the potentiallyexpensive operation. This patch adds a file called "removable" to thememory directory in sysfs to help such an agent. In this patch, a memoryblock is considered removable if;o It contains only MOVABLE pageblockso It contains only pageblocks with free pages regardless of pageblock typeOn the other hand, a memory block starting with a PageReserved() page willnever be considered removable. Without this patch, the user-agent isforced to choose a memory block to remove randomly.Sample output of the sysfs files:./memory/memory0/removable: 0./memory/memory1/removable: 0./memory/memory2/removable: 0./memory/memory3/removable: 0./memory/memory4/removable: 0./memory/memory5/removable: 0./memory/memory6/removable: 0./memory/memory7/removable: 1./memory/memory8/removable: 0./memory/memory9/removable: 0./memory/memory10/removable: 0./memory/memory11/removable: 0./memory/memory12/removable: 0./memory/memory13/removable: 0./memory/memory14/removable: 0./memory/memory15/removable: 0./memory/memory16/removable: 0./memory/memory17/removable: 1./memory/memory18/removable: 1./memory/memory19/removable: 1./memory/memory20/removable: 1./memory/memory21/removable: 1./memory/memory22/removable: 1Signed-off-by: Badari Pulavarty Signed-off-by: Mel Gorman Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds List of files: /linux-6.15/Documentation/ABI/testing/sysfs-devices-memory