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Subject: Re: [PATCH] selftests/vm: cleanup hugetlb file after mremap test
To:     Mike Kravetz <mike.kravetz@oracle.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Cc:     Mina Almasry <almasrymina@google.com>,
        Yosry Ahmed <yosryahmed@google.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Shuah Khan <shuah@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20220201033459.156944-1-mike.kravetz@oracle.com>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <33568901-8ef9-1461-0907-217634b3b989@linuxfoundation.org>
Date:   Tue, 1 Feb 2022 09:45:57 -0700
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On 1/31/22 8:34 PM, Mike Kravetz wrote:
> The hugepage-mremap test will create a file in a hugetlb filesystem.
> In a default 'run_vmtests' run, the file will contain all the hugetlb
> pages.  After the test, the file remains and there are no free hugetlb
> pages for subsequent tests. This causes those hugetlb tests to fail.
> 
> Change hugepage-mremap to take the name of the hugetlb file as an
> argument.  Unlink the file within the test, and just to be sure remove
> the file in the run_vmtests script.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
>   tools/testing/selftests/vm/hugepage-mremap.c | 26 ++++++++++++++------
>   tools/testing/selftests/vm/run_vmtests.sh    |  3 ++-
>   2 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/testing/selftests/vm/hugepage-mremap.c b/tools/testing/selftests/vm/hugepage-mremap.c
> index 2a7c33631a29..1d689084a54b 100644
> --- a/tools/testing/selftests/vm/hugepage-mremap.c
> +++ b/tools/testing/selftests/vm/hugepage-mremap.c
> @@ -3,9 +3,10 @@
>    * hugepage-mremap:
>    *
>    * Example of remapping huge page memory in a user application using the
> - * mremap system call.  Code assumes a hugetlbfs filesystem is mounted
> - * at './huge'.  The amount of memory used by this test is decided by a command
> - * line argument in MBs. If missing, the default amount is 10MB.
> + * mremap system call.  The path to a file in a hugetlbfs filesystem must
> + * be passed as the last argument to this test.  The amount of memory used
> + * by this test in MBs can optionally be passed as an argument.  If no memory
> + * amount is passed, the default amount is 10MB.
>    *
>    * To make sure the test triggers pmd sharing and goes through the 'unshare'
>    * path in the mremap code use 1GB (1024) or more.
> @@ -25,7 +26,6 @@
>   #define DEFAULT_LENGTH_MB 10UL
>   #define MB_TO_BYTES(x) (x * 1024 * 1024)
>   
> -#define FILE_NAME "huge/hugepagefile"
>   #define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
>   #define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
>   
> @@ -107,17 +107,26 @@ static void register_region_with_uffd(char *addr, size_t len)
>   
>   int main(int argc, char *argv[])
>   {
> +	size_t length;
> +
> +	if (argc != 2 && argc != 3) {
> +		printf("Usage: %s [length_in_MB] <hugetlb_file>\n", argv[0]);
> +		exit(1);
> +	}
> +
>   	/* Read memory length as the first arg if valid, otherwise fallback to
> -	 * the default length. Any additional args are ignored.
> +	 * the default length.
>   	 */
> -	size_t length = argc > 1 ? (size_t)atoi(argv[1]) : 0UL;
> +	if (argc == 3)
> +		length = argc > 2 ? (size_t)atoi(argv[1]) : 0UL;
>   

Looks like getopt() might be useful - we have a few arguments now.
Makes it easier to maintain the test.

>   	length = length > 0 ? length : DEFAULT_LENGTH_MB;
>   	length = MB_TO_BYTES(length);
>   
>   	int ret = 0;
>   
> -	int fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
> +	/* last arg is the hugetlb file name */
> +	int fd = open(argv[argc-1], O_CREAT | O_RDWR, 0755);
>   
>   	if (fd < 0) {
>   		perror("Open failed");
> @@ -169,5 +178,8 @@ int main(int argc, char *argv[])
>   
>   	munmap(addr, length);
>   
> +	close(fd);
> +	unlink(argv[argc-1]);
> +
>   	return ret;
>   }
> diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
> index e09040a3dc08..e10d50e0b8e8 100755
> --- a/tools/testing/selftests/vm/run_vmtests.sh
> +++ b/tools/testing/selftests/vm/run_vmtests.sh
> @@ -111,13 +111,14 @@ fi
>   echo "-----------------------"
>   echo "running hugepage-mremap"
>   echo "-----------------------"
> -./hugepage-mremap 256
> +./hugepage-mremap $mnt/huge_mremap
>   if [ $? -ne 0 ]; then
>   	echo "[FAIL]"
>   	exitcode=1
>   else
>   	echo "[PASS]"
>   fi
> +rm -f $mnt/huge_mremap
>   
>   echo "------------------------"
>   echo "running hugepage-vmemmap"
> 

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah