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Subject[Patch v4 4/4] mm/migrate.c: unify "not queued for migration" handling in do_pages_move()
Date
It can currently happen that we store the status of a page twice:
* Once we detect that it is already on the target node
* Once we moved a bunch of pages, and a page that's already on the
target node is contained in the current interval.

Let's simplify the code and always call do_move_pages_to_node() in
case we did not queue a page for migration. Note that pages that are
already on the target node are not added to the pagelist and are,
therefore, ignored by do_move_pages_to_node() - there is no functional
change.

The status of such a page is now only stored once.

[david@redhat.com rephrase changelog]

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
mm/migrate.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 981916007b4f..7c850fe5a1a8 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1653,18 +1653,16 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
err = add_page_for_migration(mm, addr, current_node,
&pagelist, flags & MPOL_MF_MOVE_ALL);

- if (!err) {
- /* The page is already on the target node */
- err = store_status(status, i, current_node, 1);
- if (err)
- goto out_flush;
- continue;
- } else if (err > 0) {
+ if (err > 0) {
/* The page is successfully queued for migration */
continue;
}

- err = store_status(status, i, err, 1);
+ /*
+ * If the page is already on the target node (!err), store the
+ * node, otherwise, store the err.
+ */
+ err = store_status(status, i, err ? : current_node, 1);
if (err)
goto out_flush;

--
2.17.1
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