Since commit a49bd4d71637 ("mm, numa: rework do_pages_move"), the semantic of move_pages() was changed to return the number of non-migrated pages (failed to migration) and the call would be aborted immediately if migrate_pages() returns positive value. But it didn't report the number of pages that we even haven't attempted to migrate. So, fix it by including non-attempted pages in the return value.

Fixes: a49bd4d71637 ("mm, numa: rework do_pages_move") Suggested-by: Michal Hocko mhocko@suse.com Cc: Wei Yang richardw.yang@linux.intel.com Cc: stable@vger.kernel.org [4.17+] Signed-off-by: Yang Shi yang.shi@linux.alibaba.com --- The patch is based off Wei Yang's cleanup patchset: https://lore.kernel.org/linux-mm/20200122011647.13636-1-richardw.yang@linux....

mm/migrate.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c index 591f2e5..51b1b76 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1582,7 +1582,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,

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 start, int nr, unsigned long total) { int err;

@@ -1590,8 +1590,17 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node, return 0;

err = do_move_pages_to_node(mm, pagelist, node); - if (err) + if (err) { + /* + * Possitive 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 incude the rest + * of the nr_pages that are not attempted as well. + */ + if (err > 0) + err += total - start - nr - 1; return err; + } err = store_status(status, start, node, nr); return err; } @@ -1640,7 +1649,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, start = i; } else if (node != current_node) { err = move_pages_and_store_status(mm, current_node, - &pagelist, status, start, i - start); + &pagelist, status, start, i - start, + nr_pages); if (err) goto out; start = i; @@ -1670,7 +1680,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, goto out_flush;

err = move_pages_and_store_status(mm, current_node, &pagelist, - status, start, i - start); + status, start, i - start, nr_pages); if (err) goto out; current_node = NUMA_NO_NODE; @@ -1678,7 +1688,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, out_flush: /* Make sure we do not overwrite the existing error */ err1 = move_pages_and_store_status(mm, current_node, &pagelist, - status, start, i - start); + status, start, i - start, nr_pages); if (err >= 0) err = err1; out: