mm/mempolicy: add nodes_empty check in SYSC_migrate_pages

As in manpage of migrate_pages, the errno should be set to EINVAL when
none of the node IDs specified by new_nodes are on-line and allowed by
the process's current cpuset context, or none of the specified nodes
contain memory.  However, when test by following case:

	new_nodes = 0;
	old_nodes = 0xf;
	ret = migrate_pages(pid, old_nodes, new_nodes, MAX);

The ret will be 0 and no errno is set.  As the new_nodes is empty, we
should expect EINVAL as documented.

To fix the case like above, this patch check whether target nodes AND
current task_nodes is empty, and then check whether AND
node_states[N_MEMORY] is empty.

Link: http://lkml.kernel.org/r/1510882624-44342-4-git-send-email-xieyisheng1@huawei.com
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Chris Salls <salls@cs.ucsb.edu>
Cc: Christopher Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tan Xiaojun <tanxiaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 65df28d7cc899d23523eaf905f726b38b70179c6..f604b22ebb65bb94aaf459c4e8c4356f6ab62027 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1433,10 +1433,14 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
                goto out_put;
        }
 
-       if (!nodes_subset(*new, node_states[N_MEMORY])) {
-               err = -EINVAL;
+       task_nodes = cpuset_mems_allowed(current);
+       nodes_and(*new, *new, task_nodes);
+       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)