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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Yisheng Xie <xieyisheng1@huawei.com>,
        Andi Kleen <ak@linux.intel.com>,
        Chris Salls <salls@cs.ucsb.edu>,
        Christopher Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Ingo Molnar <mingo@kernel.org>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Tan Xiaojun <tanxiaojun@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.15 120/189] mm/mempolicy: add nodes_empty check
 in SYSC_migrate_pages
Thread-Topic: [PATCH AUTOSEL for 4.15 120/189] mm/mempolicy: add nodes_empty
 check in SYSC_migrate_pages
Thread-Index: AQHTz5hEPrB6lLYRukm84/AcHaLVcA==
Date:   Mon, 9 Apr 2018 00:18:21 +0000
Message-ID: <20180409001637.162453-120-alexander.levin@microsoft.com>
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From: Yisheng Xie <xieyisheng1@huawei.com>

[ Upstream commit 0486a38bcc4749808edbc848f1bcf232042770fc ]

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 =3D 0;
	old_nodes =3D 0xf;
	ret =3D 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-xieyisheng=
1@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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 mm/mempolicy.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c9b807eca74c..277b6454954e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1435,10 +1435,14 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned=
 long, maxnode,
 		goto out_put;
 	}
=20
-	if (!nodes_subset(*new, node_states[N_MEMORY])) {
-		err =3D -EINVAL;
+	task_nodes =3D 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;
-	}
=20
 	err =3D security_task_movememory(task);
 	if (err)
--=20
2.15.1