The logic in do_pages_move() is a little mess for audience to read and has
some potential error on handling the return value. Especially there are
three calls on do_move_pages_to_node() and store_status() with almost the
same form.
This patch set tries to make the code a little friendly for audience by
consolidate the calls.
v3:
* rebase on top of Yang Shi's fix "mm: move_pages: report the number of
non-attempted pages"
v2:
* remove some unnecessary cleanup
Wei Yang (4):
mm/migrate.c: not necessary to check start and i
mm/migrate.c: wrap do_move_pages_to_node() and store_status()
mm/migrate.c: check pagelist in move_pages_and_store_status()
mm/migrate.c: handle same node and add failure in the same way
mm/migrate.c | 90 ++++++++++++++++++++++++----------------------------
1 file changed, 42 insertions(+), 48 deletions(-)
--
2.17.1
When page is not queued for migration, there are two possible cases:
* page already on the target node
* failed to add to migration queue
Current code handle them differently, this leads to a behavior
inconsistency.
Usually for each page's status, we just do store for once. While for the
page already on the target node, we might store the node information for
twice:
* once when we found the page is on the target node
* second when moving the pages to target node successfully after above
action
The reason is even we don't add the page to pagelist, but store_status()
does store in a range which still contains the page.
This patch handles these two cases in the same way to reduce this
inconsistency and also make the code a little easier to read.
Signed-off-by: Wei Yang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
---
mm/migrate.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index b123ced445b7..bb4f45b120fd 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1665,18 +1665,18 @@ 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);
+ /*
+ * Two possible cases for err here:
+ * == 0: page is already on the target node, then store
+ * current_node to status
+ * < 0: failed to add page to list, then store err to status
+ */
+ err = store_status(status, i, err ? : current_node, 1);
if (err)
goto out_flush;
--
2.17.1
When pagelist is empty, it is not necessary to do the move and store.
Also it consolidate the empty list check in one place.
Signed-off-by: Wei Yang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
---
mm/migrate.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index e816c8990296..b123ced445b7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
{
int err;
- if (list_empty(pagelist))
- return 0;
-
err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
MIGRATE_SYNC, MR_SYSCALL);
if (err)
@@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
{
int err;
+ if (list_empty(pagelist))
+ return 0;
+
err = do_move_pages_to_node(mm, pagelist, node);
if (err) {
/*
@@ -1687,9 +1687,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
current_node = NUMA_NO_NODE;
}
out_flush:
- if (list_empty(&pagelist))
- return err;
-
/* Make sure we do not overwrite the existing error */
err1 = move_pages_and_store_status(mm, current_node, &pagelist,
status, nr_pages, start, i);
--
2.17.1