Re: [PATCH v2 3/3] userfaultfd/selftests: enable huegtlb remap and remove event testing

[Mike Rapoport <rppt@kernel.org>]

On Tue, Feb 01, 2022 at 05:40:34PM -0800, Mike Kravetz wrote:
> Subject: [PATCH v2 3/3] userfaultfd/selftests: enable huegtlb remap and remove event testing

Nit:                                                  ^ hugetlb

> With MADV_DONTNEED support added to hugetlb mappings, mremap testing
> can also be enabled for hugetlb.
> 
> Modify the tests to use madvise MADV_DONTNEED and MADV_REMOVE instead of
> fallocate hole puch for releasing hugetlb pages.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
> ---
>  tools/testing/selftests/vm/run_vmtests.sh |  3 +-
>  tools/testing/selftests/vm/userfaultfd.c  | 69 ++++++++++++-----------
>  2 files changed, 36 insertions(+), 36 deletions(-)
> 
> diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
> index ff901ee66838..7178d6fa8c92 100755
> --- a/tools/testing/selftests/vm/run_vmtests.sh
> +++ b/tools/testing/selftests/vm/run_vmtests.sh
> @@ -207,14 +207,13 @@ echo "running userfaultfd_hugetlb"
>  echo "---------------------------"
>  # Test requires source and destination huge pages.  Size of source
>  # (half_ufd_size_MB) is passed as argument to test.
> -./userfaultfd hugetlb $half_ufd_size_MB 32 $mnt/ufd_test_file
> +./userfaultfd hugetlb $half_ufd_size_MB 32
>  if [ $? -ne 0 ]; then
>  	echo "[FAIL]"
>  	exitcode=1
>  else
>  	echo "[PASS]"
>  fi
> -rm -f $mnt/ufd_test_file
>  
>  echo "-------------------------"
>  echo "running userfaultfd_shmem"
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index d2480ab93037..c18beebc0dd6 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -88,7 +88,6 @@ static bool test_uffdio_minor = false;
>  static bool map_shared;
>  static int shm_fd;
>  static int huge_fd;
> -static char *huge_fd_off0;
>  static unsigned long long *count_verify;
>  static int uffd = -1;
>  static int uffd_flags, finished, *pipefd;
> @@ -127,9 +126,9 @@ const char *examples =
>      "./userfaultfd anon 100 99999\n\n"
>      "# Run share memory test on 1GiB region with 99 bounces:\n"
>      "./userfaultfd shmem 1000 99\n\n"
> -    "# Run hugetlb memory test on 256MiB region with 50 bounces (using /dev/hugepages/hugefile):\n"
> -    "./userfaultfd hugetlb 256 50 /dev/hugepages/hugefile\n\n"
> -    "# Run the same hugetlb test but using shmem:\n"
> +    "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
> +    "./userfaultfd hugetlb 256 50\n\n"
> +    "# Run the same hugetlb test but using shared file:\n"
>      "./userfaultfd hugetlb_shared 256 50 /dev/hugepages/hugefile\n\n"
>      "# 10MiB-~6GiB 999 bounces anonymous test, "
>      "continue forever unless an error triggers\n"
> @@ -226,10 +225,13 @@ static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
>  
>  static void hugetlb_release_pages(char *rel_area)
>  {
> -	if (fallocate(huge_fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
> -		      rel_area == huge_fd_off0 ? 0 : nr_pages * page_size,
> -		      nr_pages * page_size))
> -		err("fallocate() failed");
> +	if (!map_shared) {
> +		if (madvise(rel_area, nr_pages * page_size, MADV_DONTNEED))
> +			err("madvise(MADV_DONTNEED) failed");
> +	} else {
> +		if (madvise(rel_area, nr_pages * page_size, MADV_REMOVE))
> +			err("madvise(MADV_REMOVE) failed");
> +	}
>  }
>  
>  static void hugetlb_allocate_area(void **alloc_area)
> @@ -237,26 +239,37 @@ static void hugetlb_allocate_area(void **alloc_area)
>  	void *area_alias = NULL;
>  	char **alloc_area_alias;
>  
> -	*alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
> -			   (map_shared ? MAP_SHARED : MAP_PRIVATE) |
> -			   MAP_HUGETLB |
> -			   (*alloc_area == area_src ? 0 : MAP_NORESERVE),
> -			   huge_fd, *alloc_area == area_src ? 0 :
> -			   nr_pages * page_size);
> +	if (!map_shared)
> +		*alloc_area = mmap(NULL,
> +			nr_pages * page_size,
> +			PROT_READ | PROT_WRITE,
> +			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB |
> +				(*alloc_area == area_src ? 0 : MAP_NORESERVE),
> +			-1,
> +			0);
> +	else
> +		*alloc_area = mmap(NULL,
> +			nr_pages * page_size,
> +			PROT_READ | PROT_WRITE,
> +			MAP_SHARED |
> +				(*alloc_area == area_src ? 0 : MAP_NORESERVE),
> +			huge_fd,
> +			*alloc_area == area_src ? 0 : nr_pages * page_size);
>  	if (*alloc_area == MAP_FAILED)
>  		err("mmap of hugetlbfs file failed");
>  
>  	if (map_shared) {
> -		area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
> -				  MAP_SHARED | MAP_HUGETLB,
> -				  huge_fd, *alloc_area == area_src ? 0 :
> -				  nr_pages * page_size);
> +		area_alias = mmap(NULL,
> +			nr_pages * page_size,
> +			PROT_READ | PROT_WRITE,
> +			MAP_SHARED,
> +			huge_fd,
> +			*alloc_area == area_src ? 0 : nr_pages * page_size);
>  		if (area_alias == MAP_FAILED)
>  			err("mmap of hugetlb file alias failed");
>  	}
>  
>  	if (*alloc_area == area_src) {
> -		huge_fd_off0 = *alloc_area;
>  		alloc_area_alias = &area_src_alias;
>  	} else {
>  		alloc_area_alias = &area_dst_alias;
> @@ -269,12 +282,7 @@ static void hugetlb_alias_mapping(__u64 *start, size_t len, unsigned long offset
>  {
>  	if (!map_shared)
>  		return;
> -	/*
> -	 * We can't zap just the pagetable with hugetlbfs because
> -	 * MADV_DONTEED won't work. So exercise -EEXIST on a alias
> -	 * mapping where the pagetables are not established initially,
> -	 * this way we'll exercise the -EEXEC at the fs level.
> -	 */
> +
>  	*start = (unsigned long) area_dst_alias + offset;
>  }
>  
> @@ -427,7 +435,6 @@ static void uffd_test_ctx_clear(void)
>  		uffd = -1;
>  	}
>  
> -	huge_fd_off0 = NULL;
>  	munmap_area((void **)&area_src);
>  	munmap_area((void **)&area_src_alias);
>  	munmap_area((void **)&area_dst);
> @@ -925,10 +932,7 @@ static int faulting_process(int signal_test)
>  	struct sigaction act;
>  	unsigned long signalled = 0;
>  
> -	if (test_type != TEST_HUGETLB)
> -		split_nr_pages = (nr_pages + 1) / 2;
> -	else
> -		split_nr_pages = nr_pages;
> +	split_nr_pages = (nr_pages + 1) / 2;
>  
>  	if (signal_test) {
>  		sigbuf = &jbuf;
> @@ -985,9 +989,6 @@ static int faulting_process(int signal_test)
>  	if (signal_test)
>  		return signalled != split_nr_pages;
>  
> -	if (test_type == TEST_HUGETLB)
> -		return 0;
> -
>  	area_dst = mremap(area_dst, nr_pages * page_size,  nr_pages * page_size,
>  			  MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
>  	if (area_dst == MAP_FAILED)
> @@ -1670,7 +1671,7 @@ int main(int argc, char **argv)
>  	}
>  	nr_pages = nr_pages_per_cpu * nr_cpus;
>  
> -	if (test_type == TEST_HUGETLB) {
> +	if (test_type == TEST_HUGETLB && map_shared) {
>  		if (argc < 5)
>  			usage();
>  		huge_fd = open(argv[4], O_CREAT | O_RDWR, 0755);
> -- 
> 2.34.1
> 
> 

-- 
Sincerely yours,
Mike.