[PATCH 0/2] kexec command fails after cpu hot-removing
WANG Chao
chaowang at redhat.com
Thu Jun 5 00:32:15 PDT 2014
On 06/05/14 at 02:10pm, Takao Indoh wrote:
> After cpu hot-removing, kexec command fails with the following message.
>
> "/sys/devices" does not exist. Sysfs does not seem to be mounted. Try
> mounting sysfs.
>
> Of course sysfs is mounted. kexec tried to open
> /sys/devices/system/cpu/cpu30/crash_notes but it failed because
> /sys/devices/system/cpu/cpu30 did not exist.
>
>
> [Before hot-remove]
>
> # ls /sys/devices/system/cpu/
> cpu0 cpu111 cpu18 cpu31 cpu45 cpu59 cpu72 cpu86 cpuidle
> cpu1 cpu112 cpu19 cpu32 cpu46 cpu6 cpu73 cpu87 intel_pstate
> cpu10 cpu113 cpu2 cpu33 cpu47 cpu60 cpu74 cpu88 kernel_max
> cpu100 cpu114 cpu20 cpu34 cpu48 cpu61 cpu75 cpu89 microcode
> cpu101 cpu115 cpu21 cpu35 cpu49 cpu62 cpu76 cpu9 modalias
> cpu102 cpu116 cpu22 cpu36 cpu5 cpu63 cpu77 cpu90 offline
> cpu103 cpu117 cpu23 cpu37 cpu50 cpu64 cpu78 cpu91 online
> cpu104 cpu118 cpu24 cpu38 cpu51 cpu65 cpu79 cpu92 possible
> cpu105 cpu119 cpu25 cpu39 cpu52 cpu66 cpu8 cpu93 power
> cpu106 cpu12 cpu26 cpu4 cpu53 cpu67 cpu80 cpu94 present
> cpu107 cpu13 cpu27 cpu40 cpu54 cpu68 cpu81 cpu95 probe
> cpu108 cpu14 cpu28 cpu41 cpu55 cpu69 cpu82 cpu96 release
> cpu109 cpu15 cpu29 cpu42 cpu56 cpu7 cpu83 cpu97 uevent
> cpu11 cpu16 cpu3 cpu43 cpu57 cpu70 cpu84 cpu98
> cpu110 cpu17 cpu30 cpu44 cpu58 cpu71 cpu85 cpu99
>
>
> [After hot-remove]
>
> # ls /sys/devices/system/cpu/
> cpu0 cpu16 cpu23 cpu4 cpu65 cpu72 cpu8 cpu87 modalias uevent
> cpu1 cpu17 cpu24 cpu5 cpu66 cpu73 cpu80 cpu88 offline
> cpu10 cpu18 cpu25 cpu6 cpu67 cpu74 cpu81 cpu89 online
> cpu11 cpu19 cpu26 cpu60 cpu68 cpu75 cpu82 cpu9 possible
> cpu12 cpu2 cpu27 cpu61 cpu69 cpu76 cpu83 cpuidle power
> cpu13 cpu20 cpu28 cpu62 cpu7 cpu77 cpu84 intel_pstate present
> cpu14 cpu21 cpu29 cpu63 cpu70 cpu78 cpu85 kernel_max probe
> cpu15 cpu22 cpu3 cpu64 cpu71 cpu79 cpu86 microcode release
>
> You can see cpu30 to cpu59, and cpu90 to cpu119 does not exist, they are
> removed from this system by hot-remove operation.
>
> kexec command expects the number of each directory is contiguous. For
> example, if sysconf(_SC_NPROCESSORS_CONF) is 60, kexec thinks directory
> cpu0, cpu1, cpu2, .... cpu59 exists. But in this case, the number of
> directory is not contiguous. That is the root cause of this problem.
> This patches fix it.
>
> Takao Indoh (2):
> Enumerate all /sys/devices/system/cpu/cpuN when they are discontiguous
> Fix mistaken check of stat(2) return value
>
> kexec/crashdump-elf.c | 5 ++++-
> kexec/crashdump.c | 2 +-
> 2 files changed, 5 insertions(+), 2 deletions(-)
These two patches look good to me.
Acked-by: WANG Chao <chaowang at redhat.com>
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