| Message ID | 1544508709-11358-1-git-send-email-kernelfans@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv3] mm/pageblock: throw compiling time error if pageblock_bits can not hold MIGRATE_TYPES | expand |
On 12/11/18 7:11 AM, Pingfan Liu wrote: > Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. > If someone adds extra migrate type, then he may forget to enlarge the > NR_PAGEBLOCK_BITS. Hence it requires some way to fix. > NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro > spread on two different .h file with reverse dependency, it is a little > hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to > remind such relation in compiling-time. > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index 9132c5c..06a6632 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -25,10 +25,11 @@ #include <linux/types.h> +#define PB_migratetype_bits 3 /* Bit indices that affect a whole block of pages */ enum pageblock_bits { PB_migrate, - PB_migrate_end = PB_migrate + 3 - 1, + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, /* 3 bits required for migrate types */ PB_migrate_skip,/* If set the block is skipped by compaction */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2ec9cc4..29ee87e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -426,6 +426,7 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, unsigned long old_word, word; BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); + BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits)); bitmap = get_pageblock_bitmap(page, pfn); bitidx = pfn_to_bitidx(page, pfn);
Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. If someone adds extra migrate type, then he may forget to enlarge the NR_PAGEBLOCK_BITS. Hence it requires some way to fix. NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro spread on two different .h file with reverse dependency, it is a little hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to remind such relation in compiling-time. Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> --- v2->v3: using '>' instead of "==" option since NR_PAGEBLOCK_BITS allows wasted bits include/linux/pageblock-flags.h | 3 ++- mm/page_alloc.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-)