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SubjectRe: [PATCH 1/2] mm: fix bugs of mpol_rebind_nodemask()
On Thu, 22 Apr 2010, Miao Xie wrote:

> - local variable might be an empty nodemask, so must be checked before setting
> pol->v.nodes to it.
>
> - nodes_remap() may cause the weight of pol->v.nodes being monotonic decreasing.
> and never become large even we pass a nodemask with large weight after
> ->v.nodes become little.
>

That's always been the intention of rebinding a mempolicy nodemask: we
remap the current mempolicy nodes over the new nodemask given the set of
allowed nodes. The nodes_remap() shouldn't be removed.

> this patch fixes these two problem.
>
> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
> mm/mempolicy.c | 9 ++++++---
> 1 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 08f40a2..03ba9fc 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -291,12 +291,15 @@ static void mpol_rebind_nodemask(struct mempolicy *pol,
> else if (pol->flags & MPOL_F_RELATIVE_NODES)
> mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
> else {
> - nodes_remap(tmp, pol->v.nodes, pol->w.cpuset_mems_allowed,
> - *nodes);
> + tmp = *nodes;
> pol->w.cpuset_mems_allowed = *nodes;
> }
>
> - pol->v.nodes = tmp;
> + if (nodes_empty(tmp))
> + pol->v.nodes = *nodes;
> + else
> + pol->v.nodes = tmp;
> +
> if (!node_isset(current->il_next, tmp)) {
> current->il_next = next_node(current->il_next, tmp);
> if (current->il_next >= MAX_NUMNODES)


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