The patch titled
Subject: mm/pageblock: throw compile error if pageblock_bits cannot hold MIGRATE_TYPES
has been added to the -mm tree. Its filename is
mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types.patch
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------------------------------------------------------
From: Pingfan Liu <kernelfans@xxxxxxxxx>
Subject: 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@xxxxxxxxx
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pageblock-flags.h | 3 ++-
mm/page_alloc.c | 1 +
2 files changed, 3 insertions(+), 1 deletion(-)
--- a/include/linux/pageblock-flags.h~mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types
+++ a/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 */
--- a/mm/page_alloc.c~mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types
+++ a/mm/page_alloc.c
@@ -428,6 +428,7 @@ void set_pfnblock_flags_mask(struct page
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);
_
Patches currently in -mm which might be from kernelfans@xxxxxxxxx are
mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-migrate_types.patch
