2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dimitri Sivanich commit 364df0ebfbbb1330bfc6ca159f4d6020efc15a12 upstream. After downing/upping a cpu, an attempt to set /proc/sys/vm/percpu_pagelist_fraction results in an oops in percpu_pagelist_fraction_sysctl_handler(). If a processor is downed then we need to set the pageset pointer back to the boot pageset. Updates of the high water marks should not access pagesets of unpopulated zones (those pointer go to the boot pagesets which would be no longer functional if their size would be increased beyond zero). Signed-off-by: Dimitri Sivanich Signed-off-by: Christoph Lameter Reviewed-by: KOSAKI Motohiro Cc: Nick Piggin Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2764,7 +2764,7 @@ bad: if (dzone == zone) break; kfree(zone_pcp(dzone, cpu)); - zone_pcp(dzone, cpu) = NULL; + zone_pcp(dzone, cpu) = &boot_pageset[cpu]; } return -ENOMEM; } @@ -2779,7 +2779,7 @@ static inline void free_zone_pagesets(in /* Free per_cpu_pageset if it is slab allocated */ if (pset != &boot_pageset[cpu]) kfree(pset); - zone_pcp(zone, cpu) = NULL; + zone_pcp(zone, cpu) = &boot_pageset[cpu]; } } @@ -4409,6 +4409,8 @@ int percpu_pagelist_fraction_sysctl_hand if (!write || (ret == -EINVAL)) return ret; for_each_zone(zone) { + if (!populated_zone(zone)) + continue; for_each_online_cpu(cpu) { unsigned long high; high = zone->present_pages / percpu_pagelist_fraction; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/