From: Badari Pulavarty walk_memory_resource() verifies if there are holes in a given memory range, by checking against /proc/iomem. On x86/ia64 system memory is represented in /proc/iomem. On PPC64, we don't show system memory as IO resource in /proc/iomem - instead its maintained in /proc/device-tree. This patch provides a way for an architecture to provide its own walk_memory_resource() function. On PPC64, the memory region is small (16MB), contiguous and non-overlapping. So extra checking, against device-tree is not needed. Signed-off-by: Badari Pulavarty Acked-by: KAMEZAWA Hiroyuki Cc: Dave Hansen Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Kumar Gala Signed-off-by: Andrew Morton --- arch/powerpc/Kconfig | 3 +++ arch/powerpc/mm/mem.c | 16 ++++++++++++++++ kernel/resource.c | 2 +- 3 files changed, 20 insertions(+), 1 deletion(-) diff -puN arch/powerpc/Kconfig~add-arch-specific-walk_memory_remove-for-ppc64 arch/powerpc/Kconfig --- a/arch/powerpc/Kconfig~add-arch-specific-walk_memory_remove-for-ppc64 +++ a/arch/powerpc/Kconfig @@ -266,6 +266,9 @@ config HOTPLUG_CPU config ARCH_ENABLE_MEMORY_HOTPLUG def_bool y +config ARCH_HAS_WALK_MEMORY + def_bool y + config ARCH_ENABLE_MEMORY_HOTREMOVE def_bool y diff -puN arch/powerpc/mm/mem.c~add-arch-specific-walk_memory_remove-for-ppc64 arch/powerpc/mm/mem.c --- a/arch/powerpc/mm/mem.c~add-arch-specific-walk_memory_remove-for-ppc64 +++ a/arch/powerpc/mm/mem.c @@ -129,6 +129,22 @@ int __devinit arch_add_memory(int nid, u return __add_pages(zone, start_pfn, nr_pages); } +/* + * walk_memory_resource() needs to make sure there is no holes in a given + * memory range. On PPC64, since this range comes from /sysfs, the range + * is guaranteed to be valid, non-overlapping and can not contain any + * holes. By the time we get here (memory add or remove), /proc/device-tree + * is updated and correct. Only reason we need to check against device-tree + * would be if we allow user-land to specify a memory range through a + * system call/ioctl etc.. (instead of doing offline/online through /sysfs. + */ +int +walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg, + int (*func)(unsigned long, unsigned long, void *)) +{ + return (*func)(start_pfn, nr_pages, arg); +} + #endif /* CONFIG_MEMORY_HOTPLUG */ void show_mem(void) diff -puN kernel/resource.c~add-arch-specific-walk_memory_remove-for-ppc64 kernel/resource.c --- a/kernel/resource.c~add-arch-specific-walk_memory_remove-for-ppc64 +++ a/kernel/resource.c @@ -228,7 +228,7 @@ int release_resource(struct resource *ol EXPORT_SYMBOL(release_resource); -#ifdef CONFIG_MEMORY_HOTPLUG +#if defined(CONFIG_MEMORY_HOTPLUG) && !defined(CONFIG_ARCH_HAS_WALK_MEMORY) /* * Finds the lowest memory reosurce exists within [res->start.res->end) * the caller must specify res->start, res->end, res->flags. _