From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Subject: mm/mempolicy.c: remove unnecessary nodemask check in kernel_migrate_pages()
1) task_nodes = cpuset_mems_allowed(current);
-> cpuset_mems_allowed() guaranteed to return some non-empty
subset of node_states[N_MEMORY].
2) nodes_and(*new, *new, task_nodes);
-> after nodes_and(), the 'new' should be empty or appropriate
nodemask(online node and with memory).
After 1) and 2), we could remove unnecessary check whether the 'new'
AND node_states[N_MEMORY] is empty.
Link: http://lkml.kernel.org/r/20190806023634.55356-1-wangkefeng.wang@xxxxxxxxxx
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mempolicy.c | 4 ----
1 file changed, 4 deletions(-)
--- a/mm/mempolicy.c~mm-mempolicyc-remove-unnecessary-nodemask-check-in-kernel_migrate_pages
+++ a/mm/mempolicy.c
@@ -1512,10 +1512,6 @@ static int kernel_migrate_pages(pid_t pi
if (nodes_empty(*new))
goto out_put;
- nodes_and(*new, *new, node_states[N_MEMORY]);
- if (nodes_empty(*new))
- goto out_put;
-
err = security_task_movememory(task);
if (err)
goto out_put;
_
