Re: [PATCH 1/1] selftests: mm: hugepage-vmemmap fails on 64K page size systems.

(cc Muchun) On Wed, 10 Jan 2024 14:03:35 +0530 Donet Tom donettom@linux.vnet.ibm.com wrote:

The kernel sefltest mm/hugepage-vmemmap fails on architectures which has different page size other than 4K. In hugepage-vmemmap page size used is 4k so the pfn calculation will go wrong on systems which has different page size .The length of MAP_HUGETLB memory must be hugepage aligned but in hugepage-vmemmap map length is 2M so this will not get aligned if the system has differnet hugepage size.

Added psize() to get the page size and default_huge_page_size() to get the default hugepage size at run time, hugepage-vmemmap test pass on powerpc with 64K page size and x86 with 4K page size.

Result on powerpc without patch (page size 64K) *# ./hugepage-vmemmap Returned address is 0x7effff000000 whose pfn is 0 Head page flags (100000000) is invalid check_page_flags: Invalid argument *#

Result on powerpc with patch (page size 64K) *# ./hugepage-vmemmap Returned address is 0x7effff000000 whose pfn is 600 *#

Result on x86 with patch (page size 4K) *# ./hugepage-vmemmap Returned address is 0x7fc7c2c00000 whose pfn is 1dac00 *#

Signed-off-by: Donet Tom donettom@linux.vnet.ibm.com Reported-by : Geetika Moolchandani (geetika@linux.ibm.com) Tested-by : Geetika Moolchandani (geetika@linux.ibm.com)

I'll add

Fixes: b147c89cd429 ("selftests: vm: add a hugetlb test case") Cc: stable@vger.kernel.org

diff --git a/tools/testing/selftests/mm/hugepage-vmemmap.c b/tools/testing/selftests/mm/hugepage-vmemmap.c index 5b354c209e93..894d28c3dd47 100644 --- a/tools/testing/selftests/mm/hugepage-vmemmap.c +++ b/tools/testing/selftests/mm/hugepage-vmemmap.c @@ -10,10 +10,7 @@ #include <unistd.h> #include <sys/mman.h> #include <fcntl.h>

-#define MAP_LENGTH (2UL * 1024 * 1024)

-#define PAGE_SIZE 4096 +#include "vm_util.h" #define PAGE_COMPOUND_HEAD (1UL << 15) #define PAGE_COMPOUND_TAIL (1UL << 16) @@ -39,6 +36,9 @@ #define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) #endif +static size_t pagesize; +static size_t maplength;

static void write_bytes(char *addr, size_t length) { unsigned long i; @@ -56,7 +56,7 @@ static unsigned long virt_to_pfn(void *addr) if (fd < 0) return -1UL;

• lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);

• lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET); read(fd, &pagemap, sizeof(pagemap)); close(fd);

@@ -86,7 +86,7 @@ static int check_page_flags(unsigned long pfn) * this also verifies kernel has correctly set the fake page_head to tail * while hugetlb_free_vmemmap is enabled. */

• for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {

• for (i = 1; i < maplength / pagesize; i++) { read(fd, &pageflags, sizeof(pageflags)); if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS || (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {

@@ -106,18 +106,25 @@ int main(int argc, char **argv) void *addr; unsigned long pfn;

• addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);

• pagesize = psize();
• maplength = default_huge_page_size();
• if (!maplength) {

• printf("Unable to determine huge page size\n");
  

• exit(1);
  

• }
• addr = mmap(MAP_ADDR, maplength, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); exit(1); }

/* Trigger allocation of HugeTLB page. */

• write_bytes(addr, MAP_LENGTH);

• write_bytes(addr, maplength);

pfn = virt_to_pfn(addr); if (pfn == -1UL) {

• munmap(addr, MAP_LENGTH);
  

• munmap(addr, maplength);
  

  perror("virt_to_pfn"); exit(1); }

@@ -125,13 +132,13 @@ int main(int argc, char **argv) printf("Returned address is %p whose pfn is %lx\n", addr, pfn); if (check_page_flags(pfn) < 0) {

• munmap(addr, MAP_LENGTH);
  

• munmap(addr, maplength);
  

  perror("check_page_flags"); exit(1); }

/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */

• if (munmap(addr, MAP_LENGTH)) {

• if (munmap(addr, maplength)) { perror("munmap"); exit(1); }

-- 2.43.0