[PATCH 0/2] kexec command fails after cpu hot-removing

[Simon Horman]

On Thu, Jun 05, 2014 at 02:04:41PM +0800, Zhang Yanfei wrote:
> I think maybe no one had tested kexec-tools after cpu hot-remove. So
> the bug remains until today.
> 
> For both two patches:
> 
> Reviewed-by: Zhang Yanfei <zhangyanfei at cn.fujitsu.com>

On Thu, Jun 05, 2014 at 03:32:15PM +0800, WANG Chao wrote:
> 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>

Thanks, applied.