WSL2-Linux-Kernel/arch/s390/mm
Gary Hade c04fc586c1 mm: show node to memory section relationship with symlinks in sysfs
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>
2009-01-06 15:59:00 -08:00
..
Makefile [S390] guest page hinting light 2008-05-07 09:23:02 +02:00
cmm.c [S390] cmm: remove unused binary sysctls. 2007-11-20 11:13:45 +01:00
extmem.c [S390] convert dcssblk and extmem printks messages to pr_xxx macros. 2008-12-25 13:39:23 +01:00
fault.c [S390] System z large page support. 2008-04-30 13:38:47 +02:00
hugetlbpage.c hugetlb: introduce pud_huge 2008-07-24 10:47:18 -07:00
init.c mm: show node to memory section relationship with symlinks in sysfs 2009-01-06 15:59:00 -08:00
mmap.c [S390] dynamic page tables. 2008-02-09 18:24:41 +01:00
page-states.c [S390] guest page hinting light 2008-05-07 09:23:02 +02:00
pgtable.c aio: make the lookup_ioctx() lockless 2008-12-29 08:29:50 +01:00
vmem.c [S390] vmemmap: fix off-by-one bug. 2008-06-10 10:03:27 +02:00