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Srikar Dronamraju ac1788cc7d powerpc/numa: Skip onlining a offline node in kdump path 
With commit 2ea6263068 ("powerpc/topology: Get topology for shared
processors at boot"), kdump kernel on shared LPAR may crash.

The necessary conditions are
- Shared LPAR with at least 2 nodes having memory and CPUs.
- Memory requirement for kdump kernel must be met by the first N-1
  nodes where there are at least N nodes with memory and CPUs.

Example numactl of such a machine.
  $ numactl -H
  available: 5 nodes (0,2,5-7)
  node 0 cpus:
  node 0 size: 0 MB
  node 0 free: 0 MB
  node 2 cpus:
  node 2 size: 255 MB
  node 2 free: 189 MB
  node 5 cpus: 24 25 26 27 28 29 30 31
  node 5 size: 4095 MB
  node 5 free: 4024 MB
  node 6 cpus: 0 1 2 3 4 5 6 7 16 17 18 19 20 21 22 23
  node 6 size: 6353 MB
  node 6 free: 5998 MB
  node 7 cpus: 8 9 10 11 12 13 14 15 32 33 34 35 36 37 38 39
  node 7 size: 7640 MB
  node 7 free: 7164 MB
  node distances:
  node   0   2   5   6   7
    0:  10  40  40  40  40
    2:  40  10  40  40  40
    5:  40  40  10  40  40
    6:  40  40  40  10  20
    7:  40  40  40  20  10

Steps to reproduce.
1. Load / start kdump service.
2. Trigger a kdump (for example : echo c > /proc/sysrq-trigger)

When booting a kdump kernel with 2048M:

  kexec: Starting switchover sequence.
  I'm in purgatory
  Using 1TB segments
  hash-mmu: Initializing hash mmu with SLB
  Linux version 4.19.0-rc5-master+ (srikar@linux-xxu6) (gcc version 4.8.5 (SUSE Linux)) #1 SMP Thu Sep 27 19:45:00 IST 2018
  Found initrd at 0xc000000009e70000:0xc00000000ae554b4
  Using pSeries machine description
  -----------------------------------------------------
  ppc64_pft_size    = 0x1e
  phys_mem_size     = 0x88000000
  dcache_bsize      = 0x80
  icache_bsize      = 0x80
  cpu_features      = 0x000000ff8f5d91a7
    possible        = 0x0000fbffcf5fb1a7
    always          = 0x0000006f8b5c91a1
  cpu_user_features = 0xdc0065c2 0xef000000
  mmu_features      = 0x7c006001
  firmware_features = 0x00000007c45bfc57
  htab_hash_mask    = 0x7fffff
  physical_start    = 0x8000000
  -----------------------------------------------------
  numa:   NODE_DATA [mem 0x87d5e300-0x87d67fff]
  numa:     NODE_DATA(0) on node 6
  numa:   NODE_DATA [mem 0x87d54600-0x87d5e2ff]
  Top of RAM: 0x88000000, Total RAM: 0x88000000
  Memory hole size: 0MB
  Zone ranges:
    DMA      [mem 0x0000000000000000-0x0000000087ffffff]
    DMA32    empty
    Normal   empty
  Movable zone start for each node
  Early memory node ranges
    node   6: [mem 0x0000000000000000-0x0000000087ffffff]
  Could not find start_pfn for node 0
  Initmem setup node 0 [mem 0x0000000000000000-0x0000000000000000]
  On node 0 totalpages: 0
  Initmem setup node 6 [mem 0x0000000000000000-0x0000000087ffffff]
  On node 6 totalpages: 34816

  Unable to handle kernel paging request for data at address 0x00000060
  Faulting instruction address: 0xc000000008703a54
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 11 PID: 1 Comm: swapper/11 Not tainted 4.19.0-rc5-master+ #1
  NIP:  c000000008703a54 LR: c000000008703a38 CTR: 0000000000000000
  REGS: c00000000b673440 TRAP: 0380   Not tainted  (4.19.0-rc5-master+)
  MSR:  8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE>  CR: 24022022  XER: 20000002
  CFAR: c0000000086fc238 IRQMASK: 0
  GPR00: c000000008703a38 c00000000b6736c0 c000000009281900 0000000000000000
  GPR04: 0000000000000000 0000000000000000 fffffffffffff001 c00000000b660080
  GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000220
  GPR12: 0000000000002200 c000000009e51400 0000000000000000 0000000000000008
  GPR16: 0000000000000000 c000000008c152e8 c000000008c152a8 0000000000000000
  GPR20: c000000009422fd8 c000000009412fd8 c000000009426040 0000000000000008
  GPR24: 0000000000000000 0000000000000000 c000000009168bc8 c000000009168c78
  GPR28: c00000000b126410 0000000000000000 c00000000916a0b8 c00000000b126400
  NIP [c000000008703a54] bus_add_device+0x84/0x1e0
  LR [c000000008703a38] bus_add_device+0x68/0x1e0
  Call Trace:
  [c00000000b6736c0] [c000000008703a38] bus_add_device+0x68/0x1e0 (unreliable)
  [c00000000b673740] [c000000008700194] device_add+0x454/0x7c0
  [c00000000b673800] [c00000000872e660] __register_one_node+0xb0/0x240
  [c00000000b673860] [c00000000839a6bc] __try_online_node+0x12c/0x180
  [c00000000b673900] [c00000000839b978] try_online_node+0x58/0x90
  [c00000000b673930] [c0000000080846d8] find_and_online_cpu_nid+0x158/0x190
  [c00000000b673a10] [c0000000080848a0] numa_update_cpu_topology+0x190/0x580
  [c00000000b673c00] [c000000008d3f2e4] smp_cpus_done+0x94/0x108
  [c00000000b673c70] [c000000008d5c00c] smp_init+0x174/0x19c
  [c00000000b673d00] [c000000008d346b8] kernel_init_freeable+0x1e0/0x450
  [c00000000b673dc0] [c0000000080102e8] kernel_init+0x28/0x160
  [c00000000b673e30] [c00000000800b65c] ret_from_kernel_thread+0x5c/0x80
  Instruction dump:
  60000000 60000000 e89e0020 7fe3fb78 4bff87d5 60000000 7c7d1b79 4082008c
  e8bf0050 e93e0098 3b9f0010 2fa50000 <e8690060> 38630018 419e0114 7f84e378
  ---[ end trace 593577668c2daa65 ]---

However a regular kernel with 4096M (2048 gets reserved for crash
kernel) boots properly.

Unlike regular kernels, which mark all available nodes as online,
kdump kernel only marks just enough nodes as online and marks the rest
as offline at boot. However kdump kernel boots with all available
CPUs. With Commit 2ea6263068 ("powerpc/topology: Get topology for
shared processors at boot"), all CPUs are onlined on their respective
nodes at boot time. try_online_node() tries to online the offline
nodes but fails as all needed subsystems are not yet initialized.

As part of fix, detect and skip early onlining of a offline node.

Fixes: 2ea6263068 ("powerpc/topology: Get topology for shared processors at boot")
Reported-by: Pavithra Prakash <pavrampu@in.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-10-05 23:21:54 +10:00
arch powerpc/numa: Skip onlining a offline node in kdump path 2018-10-05 23:21:54 +10:00
block block: bfq: swap puts in bfqg_and_blkg_put 2018-09-06 11:32:58 -06:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto DMAengine updates for v4.19-rc1 2018-08-18 15:55:59 -07:00
Documentation Fix things so the choice of whether or not to trust RDRAND to 2018-09-09 05:54:05 -07:00
drivers Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-09 06:49:29 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs afs: Fix cell specification to permit an empty address list 2018-09-07 16:39:44 -07:00
include Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-09 06:55:27 -07:00
init Kbuild updates for v4.19 (2nd) 2018-08-25 13:40:38 -07:00
ipc ipc/shm: properly return EIDRM in shm_lock() 2018-09-04 16:45:02 -07:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-09 06:55:27 -07:00
lib lib/xz: Put CRC32_POLY_LE in xz_private.h 2018-10-02 08:44:59 +10:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm for-linus-20180906 2018-09-06 14:01:15 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-09-04 12:45:11 -07:00
samples samples/bpf: all XDP samples should unload xdp/bpf prog on SIGTERM 2018-08-16 21:55:32 +02:00
scripts Kbuild fixes for v4.19 2018-09-09 05:42:11 -07:00
security - Fix for bad debug check when converting secids to secctx 2018-09-06 09:42:14 -07:00
sound ALSA: hda: Fix several mismatch for register mask and value 2018-09-03 23:47:40 +02:00
tools selftests/powerpc: Fix Makefiles for headers_install change 2018-09-28 15:07:45 +10:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Remove obsolete kvm_unmap_hva notifier backend 2018-09-07 15:06:02 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS i2c: xiic: Record xilinx i2c with Zynq fragment 2018-09-07 13:04:45 +02:00
Makefile Linux 4.19-rc3 2018-09-09 17:26:43 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.