From: Sayali Patil Date: Thu, 21 May 2026 06:47:49 +0000 (+0530) Subject: selftests/mm: ensure destination is hugetlb-backed in hugetlb-mremap X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f20ca8972e83f111c4300c60d74314568c8964bc;p=thirdparty%2Flinux.git selftests/mm: ensure destination is hugetlb-backed in hugetlb-mremap The hugetlb-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. Update the FLAGS macro to include MAP_HUGETLB | MAP_SHARED 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. Link: https://lore.kernel.org/367644df45c65098f23e3945c6a80f4b8a8964a6.1779296493.git.sayalip@linux.ibm.com Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test") Signed-off-by: Sayali Patil Tested-by: Venkat Rao Bagalkote Cc: David Hildenbrand (Arm) Cc: Dev Jain Cc: Liam Howlett Cc: Miaohe Lin Cc: Michal Hocko Cc: Oscar Salvador Cc: "Ritesh Harjani (IBM)" Cc: Shuah Khan Cc: Zi Yan Signed-off-by: Andrew Morton --- diff --git a/tools/testing/selftests/mm/hugetlb-mremap.c b/tools/testing/selftests/mm/hugetlb-mremap.c index 00b4c2cc95a66..ed3d92e862d87 100644 --- a/tools/testing/selftests/mm/hugetlb-mremap.c +++ b/tools/testing/selftests/mm/hugetlb-mremap.c @@ -32,7 +32,7 @@ #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) static void check_bytes(char *addr) { @@ -132,23 +132,20 @@ 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));