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| author | Pingfan Liu <kernelfans@gmail.com> | 2018-12-28 00:38:43 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:51 -0800 |
| commit | 125b860b251ad226b1384b6db06be37485127f69 (patch) | |
| tree | 412bd27ba3e790e00007e53a2a8cc31f88a82f2b | |
| parent | fcf9a0ef8dc3a3fb8be9de12b0e006c85ed5dc29 (diff) | |
| download | lwn-125b860b251ad226b1384b6db06be37485127f69.tar.gz lwn-125b860b251ad226b1384b6db06be37485127f69.zip | |
mm/pageblock: throw compile error if pageblock_bits cannot hold MIGRATE_TYPES
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.
Link: http://lkml.kernel.org/r/1544508709-11358-1-git-send-email-kernelfans@gmail.com
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/pageblock-flags.h | 3 | ||||
| -rw-r--r-- | mm/page_alloc.c | 1 |
2 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index 9132c5cb41f1..06a66327333d 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 b4fcf211ca69..cd1c9d32ef9a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -431,6 +431,7 @@ 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); |