3.2.93-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Sasha Levin <[email protected]> commit 6e8b09eaf268bceac0c62e389b4bc0cb83dfb8e5 upstream. Commit 3268c63 ("mm: fix move/migrate_pages() race on task struct") has added an odd construct where 'mm' is checked for being NULL, and if it is, it would get dereferenced anyways by mput()ing it. Signed-off-by: Sasha Levin <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: KOSAKI Motohiro <[email protected]> Cc: KAMEZAWA Hiroyuki <[email protected]> Cc: Hugh Dickins <[email protected]> Acked-by: Christoph Lameter <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- mm/migrate.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1412,14 +1412,14 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, mm = get_task_mm(task); put_task_struct(task); - if (mm) { - if (nodes) - err = do_pages_move(mm, task_nodes, nr_pages, pages, - nodes, status, flags); - else - err = do_pages_stat(mm, nr_pages, pages, status); - } else - err = -EINVAL; + if (!mm) + return -EINVAL; + + if (nodes) + err = do_pages_move(mm, task_nodes, nr_pages, pages, + nodes, status, flags); + else + err = do_pages_stat(mm, nr_pages, pages, status); mmput(mm); return err;
