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 'nodemask', which is 'unsigned long', to fix this. 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. 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 Signed-off-by: Kai Huang <[email protected]> --- v1 -> v2: - Add 'Reported-by' and 'Closes" tags. - Sean - Use BITS_PER_TYPE(). - Sean - Slightly simplify changelog to simply say "increase 'maxnode' to bits of 'nodemask'" to reflect the code better. --- 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..cc329b57ce2e 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 = BITS_PER_TYPE(nodemask); int policy; char *mem; int ret; base-commit: a91cc48246605af9aeef1edd32232976d74d9502 -- 2.53.0
