Hello Nathan, On Wed, Jun 12, 2019 at 10:19 AM Nathan Lynch <nath...@linux.ibm.com> wrote: > > CPU online/offline code paths are sensitive to parts of the device > tree (various cpu node properties, cache nodes) that can be changed as > a result of a migration. > > Prevent CPU hotplug while the device tree potentially is inconsistent. > > Fixes: 410bccf97881 ("powerpc/pseries: Partition migration in the kernel") > Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
Audited the callbacks of of_reconfig_notify(). We are fine with respect to CPU-Hotplug locking. Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com> > --- > arch/powerpc/platforms/pseries/mobility.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/arch/powerpc/platforms/pseries/mobility.c > b/arch/powerpc/platforms/pseries/mobility.c > index 88925f8ca8a0..edc1ec408589 100644 > --- a/arch/powerpc/platforms/pseries/mobility.c > +++ b/arch/powerpc/platforms/pseries/mobility.c > @@ -9,6 +9,7 @@ > * 2 as published by the Free Software Foundation. > */ > > +#include <linux/cpu.h> > #include <linux/kernel.h> > #include <linux/kobject.h> > #include <linux/smp.h> > @@ -338,11 +339,19 @@ void post_mobility_fixup(void) > if (rc) > printk(KERN_ERR "Post-mobility activate-fw failed: %d\n", rc); > > + /* > + * We don't want CPUs to go online/offline while the device > + * tree is being updated. > + */ > + cpus_read_lock(); > + > rc = pseries_devicetree_update(MIGRATION_SCOPE); > if (rc) > printk(KERN_ERR "Post-mobility device tree update " > "failed: %d\n", rc); > > + cpus_read_unlock(); > + > /* Possibly switch to a new RFI flush type */ > pseries_setup_rfi_flush(); > > -- > 2.20.1 > -- Thanks and Regards gautham.