[patch 013/166] mm/migrate.c: wrap do_move_pages_to_node() and store_status()

Andrew Morton
2020-04-07T03:04:15Z

From: Wei Yang <richardw.yang@linux.intel.com>
Subject: mm/migrate.c: wrap do_move_pages_to_node() and store_status()

Usually, do_move_pages_to_node() and store_status() are used in
combination. We have three similar call sites.

Let's provide a wrapper for both function calls -
move_pages_and_store_status - to make the calling code easier to maintain
and fix (as noted by Yang Shi, the return value handling of
do_move_pages_to_node() has a flaw).

[david@redhat.com rephrase changelog]
Link: http://lkml.kernel.org/r/20200214003017.25558-3-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/migrate.c | 61 +++++++++++++++++++++++--------------------------
1 file changed, 29 insertions(+), 32 deletions(-)

--- a/mm/migrate.c~mm-migratec-wrap-do_move_pages_to_node-and-store_status
+++ a/mm/migrate.c
@@ -1602,6 +1602,29 @@ out:
return err;
}

+static int move_pages_and_store_status(struct mm_struct *mm, int node,
+ struct list_head *pagelist, int __user *status,
+ int start, int i, unsigned long nr_pages)
+{
+ int err;
+
+ err = do_move_pages_to_node(mm, pagelist, node);
+ if (err) {
+ /*
+ * Positive err means the number of failed
+ * pages to migrate. Since we are going to
+ * abort and return the number of non-migrated
+ * pages, so need to incude the rest of the
+ * nr_pages that have not been attempted as
+ * well.
+ */
+ if (err > 0)
+ err += nr_pages - i - 1;
+ return err;
+ }
+ return store_status(status, start, node, i - start);
+}
+
/*
* Migrate an array of page address onto an array of nodes and fill
* the corresponding array of status.
@@ -1645,21 +1668,8 @@ static int do_pages_move(struct mm_struc
current_node = node;
start = i;
} else if (node != current_node) {
- err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err) {
- /*
- * Positive err means the number of failed
- * pages to migrate. Since we are going to
- * abort and return the number of non-migrated
- * pages, so need to incude the rest of the
- * nr_pages that have not been attempted as
- * well.
- */
- if (err > 0)
- err += nr_pages - i - 1;
- goto out;
- }
- err = store_status(status, start, current_node, i - start);
+ err = move_pages_and_store_status(mm, current_node,
+ &pagelist, status, start, i, nr_pages);
if (err)
goto out;
start = i;
@@ -1688,13 +1698,8 @@ static int do_pages_move(struct mm_struc
if (err)
goto out_flush;

- err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err) {
- if (err > 0)
- err += nr_pages - i - 1;
- goto out;
- }
- err = store_status(status, start, current_node, i - start);
+ err = move_pages_and_store_status(mm, current_node, &pagelist,
+ status, start, i, nr_pages);
if (err)
goto out;
current_node = NUMA_NO_NODE;
@@ -1704,16 +1709,8 @@ out_flush:
return err;

/* Make sure we do not overwrite the existing error */
- err1 = do_move_pages_to_node(mm, &pagelist, current_node);
- /*
- * Don't have to report non-attempted pages here since:
- * - If the above loop is done gracefully all pages have been
- * attempted.
- * - If the above loop is aborted it means a fatal error
- * happened, should return ret.
- */
- if (!err1)
- err1 = store_status(status, start, current_node, i - start);
+ err1 = move_pages_and_store_status(mm, current_node, &pagelist,
+ status, start, i, nr_pages);
if (err >= 0)
err = err1;
out:
_