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Srikar Dronamraju e4ff77598a powerpc/numa: Handle partially initialized numa nodes 
With commit 09f49dca57 ("mm: handle uninitialized numa nodes
gracefully") NODE_DATA for even a memoryless/cpuless node is partially
initialized at boot time.

Before onlining the node, current Powerpc code checks for NODE_DATA to
be NULL. However since NODE_DATA is partially initialized, this check
will end up always being false.

This causes hotplugging a CPU to a memoryless/cpuless node to fail.

Before adding CPUs:
  $ numactl -H
  available: 1 nodes (4)
  node 4 cpus: 0 1 2 3 4 5 6 7
  node 4 size: 97372 MB
  node 4 free: 95545 MB
  node distances:
  node   4
  4:  10

  $ lparstat
  System Configuration
  type=Dedicated mode=Capped smt=8 lcpu=1 mem=99709440 kB cpus=0 ent=1.00

  %user  %sys %wait    %idle    physc %entc lbusy   app  vcsw phint
  ----- ----- -----    -----    ----- ----- ----- ----- ----- -----
  2.66  2.67  0.16    94.51     0.00  0.00  5.33  0.00 67749     0

After hotplugging 32 cores:
  $ numactl -H
  node 4 cpus: 0 1 2 3 4 5 6 7 120 121 122 123 124 125 126 127 128 129 130
  131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148
  149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166
  167 168 169 170 171 172 173 174 175
  node 4 size: 97372 MB
  node 4 free: 93636 MB
  node distances:
  node   4
  4:  10

  $ lparstat
  System Configuration
  type=Dedicated mode=Capped smt=8 lcpu=33 mem=99709440 kB cpus=0 ent=33.00

  %user  %sys %wait    %idle    physc %entc lbusy   app  vcsw phint
  ----- ----- -----    -----    ----- ----- ----- ----- ----- -----
  0.04  0.02  0.00    99.94     0.00  0.00  0.06  0.00 1128751     3

As we can see numactl is listing only 8 cores while lparstat is showing
33 cores.

Also dmesg is showing messages like:
  [ 2261.318350 ] BUG: arch topology borken
  [ 2261.318357 ]      the DIE domain not a subset of the NODE domain

Fixes: 09f49dca57 ("mm: handle uninitialized numa nodes gracefully")
Reported-by: Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220330135123.1868197-1-srikar@linux.vnet.ibm.com
History 2022-03-31 23:23:18 +11:00
arch powerpc/numa: Handle partially initialized numa nodes 2022-03-31 23:23:18 +11:00
block for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
certs KEYS: Introduce link restriction for machine keys 2022-03-08 13:55:52 +02:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation - qcom: add support for MSM8976 2022-03-27 14:21:57 -07:00
drivers - qcom: add support for MSM8976 2022-03-27 14:21:57 -07:00
fs Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a 2022-03-27 10:17:23 -07:00
include - qcom: add support for MSM8976 2022-03-27 14:21:57 -07:00
init Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a 2022-03-27 10:17:23 -07:00
lib memcpy updates for v5.18-rc1 2022-03-26 12:19:04 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm memblock: test suite and a small cleanup 2022-03-27 13:36:06 -07:00
net The highlights are: 2022-03-24 18:32:48 -07:00
samples Landlock updates for v5.18-rc1 2022-03-27 14:26:47 -07:00
scripts Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a 2022-03-27 10:17:23 -07:00
security Landlock updates for v5.18-rc1 2022-03-27 14:26:47 -07:00
sound Add support for Intel CET-IBT, available since Tigerlake (11th gen), which is a 2022-03-27 10:17:23 -07:00
tools perf tools changes for v5.18: 1st batch 2022-03-27 13:42:32 -07:00
usr reiserfs_xattr.h: add linux/reiserfs_xattr.h to UAPI compile-test coverage 2022-02-17 09:09:38 +01:00
virt KVM: compat: riscv: Prevent KVM_COMPAT from being selected 2022-03-11 19:02:15 +05:30
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: Update Jisheng's email address 2022-03-08 17:30:32 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS memblock: test suite and a small cleanup 2022-03-27 13:36:06 -07:00
Makefile array-bounds updates for v5.18-rc1 2022-03-26 12:30:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.