[PATCH -next] mm, compaction: remove set but not used variables 'a, b, c'

[YueHaibing]

Fixes gcc '-Wunused-but-set-variable' warning:

mm/compaction.c: In function 'compact_zone':
mm/compaction.c:2063:22: warning:
 variable 'c' set but not used [-Wunused-but-set-variable]
mm/compaction.c:2063:19: warning:
 variable 'b' set but not used [-Wunused-but-set-variable]
mm/compaction.c:2063:16: warning:
 variable 'a' set but not used [-Wunused-but-set-variable]

This never used since 94d5992baaa5 ("mm, compaction: finish pageblock
scanning on contention")

Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 mm/compaction.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index f73fe07..529f19a 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2060,7 +2060,6 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 	unsigned long last_migrated_pfn;
 	const bool sync = cc->mode != MIGRATE_ASYNC;
 	bool update_cached;
-	unsigned long a, b, c;
 
 	cc->migratetype = gfpflags_to_migratetype(cc->gfp_mask);
 	ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags,
@@ -2106,10 +2105,6 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
 			cc->whole_zone = true;
 	}
 
-	a = cc->migrate_pfn;
-	b = cc->free_pfn;
-	c = (cc->free_pfn - cc->migrate_pfn) / pageblock_nr_pages;
-
 	last_migrated_pfn = 0;
 
 	/*