On Tue, Sep 20, 2016 at 05:12:16PM +0200, Vlastimil Babka wrote: > [CC += linux-api@xxxxxxxxxxxxxxx] > > Since this is a kernel-user-space API change, please CC linux-api@. The > kernel source file Documentation/SubmitChecklist notes that all Linux kernel > patches that change userspace interfaces should be CCed to > linux-api@xxxxxxxxxxxxxxx, so that the various parties who are interested in > API changes are informed. For further information, see > https://www.kernel.org/doc/man-pages/linux-api-ml.html > > I think man page should document the change? Also I noticed that MPOL_NUMA > itself is missing in the man page... > > On 09/18/2016 01:29 PM, Piotr Kwapulinski wrote: > > The MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES flags are irrelevant > > when setting them for MPOL_LOCAL NUMA memory policy via set_mempolicy. > > Return the "invalid argument" from set_mempolicy whenever > > any of these flags is passed along with MPOL_LOCAL. > > It is consistent with MPOL_PREFERRED passed with empty nodemask. > > It also slightly shortens the execution time in paths where these flags > > are used e.g. when trying to rebind the NUMA nodes for changes in > > cgroups cpuset mems (mpol_rebind_preferred()) or when just printing > > the mempolicy structure (/proc/PID/numa_maps). > > Hmm not sure I understand. How does change in mpol_new() affect > mpol_rebind_preferred()? When MPOL_LOCAL is passed to set_mempolicy along with empty nodemask it is transformed into MPOL_PREFERRED (inside mpol_new()). Unlike MPOL_PREFERRED the MPOL_LOCAL may be set along with MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES flag (inconsistency). Later on when the set of allowed NUMA nodes is changed by cgroups cpuset.mems the mpol_rebind_preferred() is called. Because one of the flags is set the unnecessary code is executed. The same is for mpol_to_str(). > > Vlastimil > > > Isolated tests done. > > > > Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@xxxxxxxxx> > > --- > > mm/mempolicy.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > > index 2da72a5..27b07d1 100644 > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -276,7 +276,9 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, > > return ERR_PTR(-EINVAL); > > } > > } else if (mode == MPOL_LOCAL) { > > - if (!nodes_empty(*nodes)) > > + if (!nodes_empty(*nodes) || > > + (flags & MPOL_F_STATIC_NODES) || > > + (flags & MPOL_F_RELATIVE_NODES)) > > return ERR_PTR(-EINVAL); > > mode = MPOL_PREFERRED; > > } else if (nodes_empty(*nodes)) > > > -- Piotr Kwapulinski -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
