linux-kernel - Re: [PATCH] selftests: hugetlb_dio: Check for initial conditions to skip in the start

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Message-ID: <5883b1c0-13c6-4593-9dd5-17f34c1319fe@linux.ibm.com>
Date: Fri, 8 Nov 2024 16:05:08 +0530
From: Donet Tom <donettom@...ux.ibm.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>
Cc: kernel@...labora.com, linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests: hugetlb_dio: Check for initial conditions to
 skip in the start


On 11/1/24 19:45, Muhammad Usama Anjum wrote:
> The test should be skipped if initial conditions aren't fulfilled in
> the start instead of failing and outputting non-compliant TAP logs. This
> kind of failure pollutes the results. The initial conditions are:
> - The test should only execute if /tmp file can be allocated.
> - The test should only execute if huge pages are free.
>
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
> ---
> Before:
> TAP version 13
> 1..4
> Bail out! Error opening file
> : Read-only file system (30)
>   # Planned tests != run tests (4 != 0)
>   # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> After:
> TAP version 13
> 1..0 # SKIP Unable to allocate file: Read-only file system
> ---
>   tools/testing/selftests/mm/hugetlb_dio.c | 19 ++++++++++++-------
>   1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
> index f9ac20c657ec6..60001c142ce99 100644
> --- a/tools/testing/selftests/mm/hugetlb_dio.c
> +++ b/tools/testing/selftests/mm/hugetlb_dio.c
> @@ -44,13 +44,6 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off)
>   	if (fd < 0)
>   		ksft_exit_fail_perror("Error opening file\n");
>   
> -	/* Get the free huge pages before allocation */
> -	free_hpage_b = get_free_hugepages();

Hi Muhammed Usman Anjum

Reading the free pages is required before starting the test. This value will be compared to the free pages after the test. If they are not the same, the test will be considered a failure.

Since reading the free pages before the test was removed,|free_hpage_b|  is always 0, causing the test to fail.

./tools/testing/selftests/mm/hugetlb_dio TAP version 13 1..4 # No. Free 
pages before allocation : 0 # No. Free pages after munmap : 100 not ok 1 
: Huge pages not freed! # No. Free pages before allocation : 0 # No. 
Free pages after munmap : 100 not ok 2 : Huge pages not freed! # No. 
Free pages before allocation : 0 # No. Free pages after munmap : 100 not 
ok 3 : Huge pages not freed! # No. Free pages before allocation : 0 # 
No. Free pages after munmap : 100 not ok 4 : Huge pages not freed! # 
Totals: pass:0 fail:4 xfail:0 xpass:0 skip:0 error:0 I think below 
changes are required. --- a/tools/testing/selftests/mm/hugetlb_dio.c +++ 
b/tools/testing/selftests/mm/hugetlb_dio.c @@ -44,6 +44,9 @@ void 
run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) if 
(fd < 0) ksft_exit_fail_perror("Error opening file\n"); + /* Get the 
free huge pages before allocation */ + free_hpage_b = 
get_free_hugepages(); + /* Allocate a hugetlb page */ orig_buffer = 
mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0); if (orig_buffer == 
MAP_FAILED) { With this change the tests are passing. 
./tools/testing/selftests/mm/hugetlb_dio TAP version 13 1..4 # No. Free 
pages before allocation : 100 # No. Free pages after munmap : 100 ok 1 : 
Huge pages freed successfully ! # No. Free pages before allocation : 100 
# No. Free pages after munmap : 100 ok 2 : Huge pages freed successfully 
! # No. Free pages before allocation : 100 # No. Free pages after munmap 
: 100 ok 3 : Huge pages freed successfully ! # No. Free pages before 
allocation : 100 # No. Free pages after munmap : 100 ok 4 : Huge pages 
freed successfully ! # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 
error:0 Thank

Donet

> -	if (free_hpage_b == 0) {
> -		close(fd);
> -		ksft_exit_skip("No free hugepage, exiting!\n");
> -	}
> -
>   	/* Allocate a hugetlb page */
>   	orig_buffer = mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0);
>   	if (orig_buffer == MAP_FAILED) {
> @@ -94,8 +87,20 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off)
>   int main(void)
>   {
>   	size_t pagesize = 0;
> +	int fd;
>   
>   	ksft_print_header();
> +
> +	/* Open the file to DIO */
> +	fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
> +	if (fd < 0)
> +		ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno));
> +	close(fd);
> +
> +	/* Check if huge pages are free */
> +	if (!get_free_hugepages())
> +		ksft_exit_skip("No free hugepage, exiting\n");
> +
>   	ksft_set_plan(4);
>   
>   	/* Get base page size */