On Wed, 2013-05-29 at 10:10 -0700, Dave Hansen wrote: > If I boot with: maxcpus=2 possible_cpus=4, I get > > # grep . /sys/devices/system/cpu/cpu[0-9]*/online' > /sys/devices/system/cpu/cpu1/online:1 > /sys/devices/system/cpu/cpu2/online:1 > /sys/devices/system/cpu/cpu3/online:1 > > on bad kernels, and this on working ones: > > /sys/devices/system/cpu/cpu1/online:1 > /sys/devices/system/cpu/cpu2/online:0 > /sys/devices/system/cpu/cpu3/online:0 > > > I also get -EINVAL if I try to re-offline them in this state. 2 and 3 > don't show up in /proc/cpuinfo, so sysfs just looks broken here. This > happens in a KVM guest, so it should be dirt-simple for anyone to reproduce. > > I bisected it down to: > > > commit 0902a9044fa5b7a0456ea4daacec2c2b3189ba8c > > Author: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Date: Fri May 3 00:25:49 2013 +0200 > > > > Driver core: Use generic offline/online for CPU offline/online > > > > Rework the CPU hotplug code in drivers/base/cpu.c to use the > > generic offline/online support introduced previously instead of > > its own CPU-specific code. > > > > For this purpose, modify cpu_subsys to provide offline and online > > callbacks for CONFIG_HOTPLUG_CPU set and remove the code handling > > the CPU-specific 'online' sysfs attribute. > > > > This modification is not supposed to change the user-observable > > behavior of the kernel (i.e. the 'online' attribute will be present > > in exactly the same place in sysfs and should trigger exactly the > > same actions as before). > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > Reviewed-by: Toshi Kani <toshi.kani@xxxxxx> Thanks for the report. The following patch fixes the problem. -Toshi ==== From: Toshi Kani <toshi.kani@xxxxxx> Subject: [PATCH] ACPI: Fix sysfs cpu/online of offlined cpus As reported by Dave Hansen, sysfs cpu/online shows 1 for offlined cpus at boot. https://lkml.org/lkml/2013/5/29/403 Fix this problem by initializing dev.offline with cpu_online() when registering a cpu. Reported-by: Dave Hansen <dave.hansen@xxxxxxxxx> Signed-off-by: Toshi Kani <toshi.kani@xxxxxx> --- drivers/base/cpu.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 130ba0b..b9f0eec 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -281,6 +281,7 @@ int __cpuinit register_cpu(struct cpu *cpu, int num) cpu->dev.bus = &cpu_subsys; cpu->dev.release = cpu_device_release; cpu->dev.offline_disabled = !cpu->hotpluggable; + cpu->dev.offline = !cpu_online(num); #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE cpu->dev.bus->uevent = arch_cpu_uevent; #endif -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
