On 12/06/2013 09:41 AM, Joonsoo Kim wrote:
migrate_pages() should return number of pages not migrated or error code.
When unmap_and_move return -EAGAIN, outer loop is re-execution without
initialising nr_failed. This makes nr_failed over-counted.
So this patch correct it by initialising nr_failed in outer loop.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
diff --git a/mm/migrate.c b/mm/migrate.c
index 3747fcd..1f59ccc 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1102,6 +1102,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
for(pass = 0; pass < 10 && retry; pass++) {
retry = 0;
+ nr_failed = 0;
list_for_each_entry_safe(page, page2, from, lru) {
cond_resched();
If I'm reading the code correctly, unmap_and_move() (and
unmap_and_move_huge_page() as well) deletes all pages from the 'from'
list, unless it fails with -EAGAIN. So the only pages you see in
subsequent passes are those that failed with -EAGAIN and those are not
counted as nr_failed. So there shouldn't be over-count, but your patch
could result in under-count.
Perhaps a comment somewhere would clarify this.
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