The hugepage-mremap selftest reserves the destination address using a anonymous base-page mapping before calling mremap() with MREMAP_FIXED, while the source region is hugetlb-backed. When remapping a hugetlb mapping into a base-page VMA may fail with: mremap: Device or resource busy This is observed on powerpc hash MMU systems where slice constraints and page size incompatibilities prevent the remap. Ensure the destination region is created using MAP_HUGETLB so that both source and destination VMAs are hugetlb-backed and compatible. Also add MAP_POPULATE to the destination mapping to prefault hugepages, matching the behaviour used for other hugetlb mapping in the test and ensuring deterministic behaviour. Update the FLAGS macro to include MAP_HUGETLB | MAP_SHARED | MAP_POPULATE so that both mappings are hugetlb-backed and compatible. Also use the macro for the mmap() calls to avoid repeating the flag combination. This ensures the test reliably exercises hugetlb mremap instead of failing due to VMA type mismatch. Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test") Acked-by: Zi Yan Signed-off-by: Sayali Patil --- tools/testing/selftests/mm/hugepage-mremap.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c index e611249080d6..48c24a4ba9a7 100644 --- a/tools/testing/selftests/mm/hugepage-mremap.c +++ b/tools/testing/selftests/mm/hugepage-mremap.c @@ -31,7 +31,7 @@ #define MB_TO_BYTES(x) (x * 1024 * 1024) #define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC) -#define FLAGS (MAP_SHARED | MAP_ANONYMOUS) +#define FLAGS (MAP_HUGETLB | MAP_SHARED | MAP_POPULATE) static void check_bytes(char *addr) { @@ -121,23 +121,20 @@ int main(int argc, char *argv[]) /* mmap to a PUD aligned address to hopefully trigger pmd sharing. */ unsigned long suggested_addr = 0x7eaa40000000; - void *haddr = mmap((void *)suggested_addr, length, PROTECTION, - MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0); + void *haddr = mmap((void *)suggested_addr, length, PROTECTION, FLAGS, fd, 0); ksft_print_msg("Map haddr: Returned address is %p\n", haddr); if (haddr == MAP_FAILED) ksft_exit_fail_msg("mmap1: %s\n", strerror(errno)); /* mmap again to a dummy address to hopefully trigger pmd sharing. */ suggested_addr = 0x7daa40000000; - void *daddr = mmap((void *)suggested_addr, length, PROTECTION, - MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0); + void *daddr = mmap((void *)suggested_addr, length, PROTECTION, FLAGS, fd, 0); ksft_print_msg("Map daddr: Returned address is %p\n", daddr); if (daddr == MAP_FAILED) ksft_exit_fail_msg("mmap3: %s\n", strerror(errno)); suggested_addr = 0x7faa40000000; - void *vaddr = - mmap((void *)suggested_addr, length, PROTECTION, FLAGS, -1, 0); + void *vaddr = mmap((void *)suggested_addr, length, PROTECTION, FLAGS, fd, 0); ksft_print_msg("Map vaddr: Returned address is %p\n", vaddr); if (vaddr == MAP_FAILED) ksft_exit_fail_msg("mmap2: %s\n", strerror(errno)); -- 2.52.0