On Mon, 2026-03-02 at 07:57 -0800, Sean Christopherson wrote: > On Mon, Mar 02, 2026, Kai Huang wrote: > > Increase 'maxnode' when using 'get_mempolicy' syscall in guest_memfd > > mmap and NUMA policy tests to fix a failure on one Intel GNR platform. > > > > On a CXL-capable platform, the memory affinity of CXL memory regions may > > not be covered by the SRAT. Since each CXL memory region is enumerated > > via a CFMWS table, at early boot the kernel parses all CFMWS tables to > > detect all CXL memory regions and assigns a 'faked' NUMA node for each > > of them, starting from the highest NUMA node ID enumerated via the SRAT. > > > > This increases the 'nr_node_ids'. E.g., on the aforementioned Intel GNR > > platform which has 4 NUMA nodes and 18 CFMWS tables, it increases to 22. > > > > This results in the 'get_mempolicy' syscall failure on that platform, > > because currently 'maxnode' is hard-coded to 8 but the 'get_mempolicy' > > syscall requires the 'maxnode' to be not smaller than the 'nr_node_ids'. > > > > Increase the 'maxnode' to the number of bits of 'unsigned long' (i.e., > > 64 on 64-bit systems) to fix this. Note the 'nodemask' is 'unsigned > > long', so it makes sense to set 'maxnode' to bits of 'unsigned long' > > anyway. > > > > This may not cover all systems. Perhaps a better way is to always set > > the 'nodemask' and 'maxnode' based on the actual maximum NUMA node ID on > > the system, but for now just do the simple way. > > > > Can you add: > > Reported-by: Yi Lai <[email protected]> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221014 > Closes: > https://lore.kernel.org/all/[email protected]%2F
Oh I didn't know this was already reported. Will do. > > > Signed-off-by: Kai Huang <[email protected]> > > --- > > tools/testing/selftests/kvm/guest_memfd_test.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c > > b/tools/testing/selftests/kvm/guest_memfd_test.c > > index 618c937f3c90..b434612bc3ec 100644 > > --- a/tools/testing/selftests/kvm/guest_memfd_test.c > > +++ b/tools/testing/selftests/kvm/guest_memfd_test.c > > @@ -80,7 +80,7 @@ static void test_mbind(int fd, size_t total_size) > > { > > const unsigned long nodemask_0 = 1; /* nid: 0 */ > > unsigned long nodemask = 0; > > - unsigned long maxnode = 8; > > + unsigned long maxnode = sizeof(nodemask) * 8; > > Pretty sure this can be: > > unsigned long maxnode = BITS_PER_TYPE(nodemask) Yeah. Will update and send out v2 soon since this is a simple patch.
