On Wed 17-03-21 11:40:01, Feng Tang wrote: > 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 */ Now you have confused me. I thought that MPOL_PREFERRED_MANY for NULL nodemask will be disallowed as it is effectively MPOL_PREFERRED aka MPOL_F_LOCAL. Or do I misread the code? > 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 -- Michal Hocko SUSE Labs
