[PATCH] mm/rmap.c: remove set but not used variable 'cstart'

[YueHaibing]

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

mm/rmap.c: In function page_mkclean_one:
mm/rmap.c:906:17: warning: variable cstart set but not used 
[-Wunused-but-set-variable]

It is not used any more since
commit cdb07bdea28e ("mm/rmap.c: remove redundant variable cend")

Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 mm/rmap.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index ec1af8b..40e4def 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -903,10 +903,9 @@ static bool page_mkclean_one(struct page *page, struct 
vm_area_struct *vma,
        mmu_notifier_invalidate_range_start(&range);
 
        while (page_vma_mapped_walk(&pvmw)) {
-               unsigned long cstart;
                int ret = 0;
 
-               cstart = address = pvmw.address;
+               address = pvmw.address;
                if (pvmw.pte) {
                        pte_t entry;
                        pte_t *pte = pvmw.pte;
@@ -933,7 +932,6 @@ static bool page_mkclean_one(struct page *page, struct 
vm_area_struct *vma,
                        entry = pmd_wrprotect(entry);
                        entry = pmd_mkclean(entry);
                        set_pmd_at(vma->vm_mm, address, pmd, entry);
-                       cstart &= PMD_MASK;
                        ret = 1;
 #else
                        /* unexpected pmd-mapped page? */
-- 
2.7.4