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    Subject[PATCH AUTOSEL for 4.14 100/161] mm/mempolicy: add nodes_empty check in SYSC_migrate_pages
    Date
    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 = 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>
    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 80b67805b51d..2d3077ce50cd 100644
    --- a/mm/mempolicy.c
    +++ b/mm/mempolicy.c
    @@ -1440,10 +1440,14 @@ 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)
    --
    2.15.1
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