Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com --- arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c index cd3e1f8..08ad637 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -20,7 +20,7 @@ static int __init topology_init(void) for_each_present_cpu(i) { struct cpu *c = &per_cpu(cpu_devices, i);
- c->hotpluggable = 1; + c->hotpluggable = !!i; ret = register_cpu(c, i); if (ret) printk(KERN_WARNING "topology_init: register_cpu %d "
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com
arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c index cd3e1f8..08ad637 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -20,7 +20,7 @@ static int __init topology_init(void) for_each_present_cpu(i) { struct cpu *c = &per_cpu(cpu_devices, i);
c->hotpluggable = 1;
c->hotpluggable = !!i; ret = register_cpu(c, i); if (ret) printk(KERN_WARNING "topology_init: register_cpu %d "-- 2.7.0
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com
arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c index cd3e1f8..08ad637 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -20,7 +20,7 @@ static int __init topology_init(void) for_each_present_cpu(i) { struct cpu *c = &per_cpu(cpu_devices, i);
c->hotpluggable = 1;
c->hotpluggable = !!i;
Seems to be the same as what xtensa did, so it's probably not a big deal.
thanks,
greg k-h
Hi Greg,
On Sat, Jul 25, 2020 at 2:49 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable.
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com
arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c index cd3e1f8..08ad637 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -20,7 +20,7 @@ static int __init topology_init(void) for_each_present_cpu(i) { struct cpu *c = &per_cpu(cpu_devices, i);
c->hotpluggable = 1;
c->hotpluggable = !!i;Seems to be the same as what xtensa did, so it's probably not a big deal.
thanks,
greg k-h
On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote:
Hi Greg,
On Sat, Jul 25, 2020 at 2:49 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable.
Is that always true?
Hi, Greg,
On Sat, Jul 25, 2020 at 3:45 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote:
Hi Greg,
On Sat, Jul 25, 2020 at 2:49 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable.
Is that always true?
Yes, someone who meet the same problem report a bug to LTP, and LTP maintainer said that this should be fixed in kernel.
Huacai
On Sat, Jul 25, 2020 at 04:29:28PM +0800, Huacai Chen wrote:
Hi, Greg,
On Sat, Jul 25, 2020 at 3:45 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote:
Hi Greg,
On Sat, Jul 25, 2020 at 2:49 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable.
Is that always true?
Yes, someone who meet the same problem report a bug to LTP, and LTP maintainer said that this should be fixed in kernel.
So the action _always_ has to succeed and can never return an error? That feels wrong even for normal systems.
thanks,
greg k-h
在 2020/7/25 下午4:57, Greg KH 写道:
On Sat, Jul 25, 2020 at 04:29:28PM +0800, Huacai Chen wrote:
Hi, Greg,
On Sat, Jul 25, 2020 at 3:45 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote:
Hi Greg,
On Sat, Jul 25, 2020 at 2:49 PM Greg KH gregkh@linuxfoundation.org wrote:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen chenhc@lemote.com wrote: > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > /system/cpu/cpu0/online which confuses some user-space tools.
What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right?
It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable.
Is that always true?
Yes, someone who meet the same problem report a bug to LTP, and LTP maintainer said that this should be fixed in kernel.
So the action _always_ has to succeed and can never return an error? That feels wrong even for normal systems.
If that returns error then it means kernel's hotplug function is not working as expected. Thus, LTP as a testsuit will consider the error as a indicator of malfunction kernel.
Thanks
- Jiaxun
thanks,
greg k-h
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
I'm ok with the patch, I'm just wondering if this is a hardware or software limitation. If it's the latter, what needs to be done to support it ?
Thomas.
在 2020/7/26 下午4:25, Thomas Bogendoerfer 写道:
On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote:
Hi, Thomas,
What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0.
I'm ok with the patch, I'm just wondering if this is a hardware or software limitation. If it's the latter, what needs to be done to support it ?
It should be a software limitation, x86 have already deal with that [1]. But there is no reason to spend extra effort on CPU0 hotplug. I don't think any user is expecting this feature.
Thanks.
[1]: https://events.static.linuxfound.org/sites/events/files/lcjpcojp13_fenghua.p...
- Jiaxun
Thomas.
On Thu, Jul 16, 2020 at 06:40:23PM +0800, Huacai Chen wrote:
Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools.
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com
arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
applied to mips-next.
Thomas.
linux-stable-mirror@lists.linaro.org
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Greg KH -
Huacai Chen -
Huacai Chen -
Jiaxun Yang -
Thomas Bogendoerfer