[PATCH] mm/migrate: Fix early increment of migrate->npages

[Reza Arbab]

The intention here is to set the same array element in src and dst.
Switch the order of these lines so that migrate->npages is only
incremented after we've used it.

Fixes: 8315ada7f095 ("mm/migrate: allow migrate_vma() to alloc new page on empty entry")
Cc: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
Signed-off-by: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index dea0ceb..c4546cc 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2146,8 +2146,8 @@ static int migrate_vma_collect_hole(unsigned long start,
 	unsigned long addr;
 
 	for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) {
-		migrate->src[migrate->npages++] = MIGRATE_PFN_MIGRATE;
 		migrate->dst[migrate->npages] = 0;
+		migrate->src[migrate->npages++] = MIGRATE_PFN_MIGRATE;
 		migrate->cpages++;
 	}
 
-- 
1.8.3.1