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.
v4:
* rephrase changelog based on suggestion from David Hildenbrand
* trivial change on code style and comment
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: no need to check for i > start in do_pages_move()
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: unify "not queued for migration" handling in
do_pages_move()
mm/migrate.c | 54 ++++++++++++++++++++++++++--------------------------
1 file changed, 27 insertions(+), 27 deletions(-)
--
2.17.1
At this point, we always have i >= start. If i == start, store_status()
will return 0. So we can drop the check for i > start.
[[email protected] rephrase changelog]
Signed-off-by: Wei Yang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
---
mm/migrate.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 430fdccc733e..4c2a21856717 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1661,11 +1661,9 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
err = do_move_pages_to_node(mm, &pagelist, current_node);
if (err)
goto out;
- if (i > start) {
- err = store_status(status, start, current_node, i - start);
- if (err)
- goto out;
- }
+ err = store_status(status, start, current_node, i - start);
+ if (err)
+ goto out;
current_node = NUMA_NO_NODE;
}
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]>
Reviewed-by: David Hildenbrand <[email protected]>
---
mm/migrate.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 92e8c9396368..981916007b4f 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)
return err;
@@ -1675,9 +1675,6 @@ 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, start, i - start);
--
2.17.1
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).
[[email protected] rephrase changelog]
Signed-off-by: Wei Yang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
---
mm/migrate.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 4c2a21856717..92e8c9396368 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1583,6 +1583,18 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
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 nr)
+{
+ int err;
+
+ err = do_move_pages_to_node(mm, pagelist, node);
+ if (err)
+ return err;
+ return store_status(status, start, node, nr);
+}
+
/*
* Migrate an array of page address onto an array of nodes and fill
* the corresponding array of status.
@@ -1626,10 +1638,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
current_node = node;
start = i;
} else if (node != current_node) {
- err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err)
- goto out;
- err = store_status(status, start, current_node, i - start);
+ err = move_pages_and_store_status(mm, current_node,
+ &pagelist, status, start, i - start);
if (err)
goto out;
start = i;
@@ -1658,10 +1668,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
if (err)
goto out_flush;
- err = do_move_pages_to_node(mm, &pagelist, current_node);
- if (err)
- goto out;
- err = store_status(status, start, current_node, i - start);
+ err = move_pages_and_store_status(mm, current_node, &pagelist,
+ status, start, i - start);
if (err)
goto out;
current_node = NUMA_NO_NODE;
@@ -1671,9 +1679,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
return err;
/* Make sure we do not overwrite the existing error */
- err1 = do_move_pages_to_node(mm, &pagelist, current_node);
- if (!err1)
- err1 = store_status(status, start, current_node, i - start);
+ err1 = move_pages_and_store_status(mm, current_node, &pagelist,
+ status, start, i - start);
if (err >= 0)
err = err1;
out:
--
2.17.1
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.
[[email protected] rephrase changelog]
Signed-off-by: Wei Yang <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
---
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