From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Create a helper function (mpol_new_preferred_many()) which is usable both by the old, single-node MPOL_PREFERRED and the new MPOL_PREFERRED_MANY. Enforce the old single-node MPOL_PREFERRED behavior in the "new" version of mpol_new_preferred() which calls mpol_new_preferred_many(). v3: * fix a stack overflow caused by emty nodemask (Feng) Link: https://lore.kernel.org/r/20200630212517.308045-5-ben.widawsky@xxxxxxxxx Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx> --- mm/mempolicy.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 1228d8e..6fb2cab 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -203,17 +203,34 @@ static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes) return 0; } -static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes) +static int mpol_new_preferred_many(struct mempolicy *pol, + const nodemask_t *nodes) { if (!nodes) pol->flags |= MPOL_F_LOCAL; /* local allocation */ else if (nodes_empty(*nodes)) return -EINVAL; /* no allowed nodes */ else - pol->v.preferred_nodes = nodemask_of_node(first_node(*nodes)); + pol->v.preferred_nodes = *nodes; return 0; } +static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes) +{ + if (nodes) { + /* MPOL_PREFERRED can only take a single node: */ + nodemask_t tmp; + + if (nodes_empty(*nodes)) + return -EINVAL; + + tmp = nodemask_of_node(first_node(*nodes)); + return mpol_new_preferred_many(pol, &tmp); + } + + return mpol_new_preferred_many(pol, NULL); +} + static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes) { if (nodes_empty(*nodes)) -- 2.7.4
