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Message-ID: <c1c55bdb-78cd-4b74-b9e5-2667dfdf9b2a@p183>
Date: Mon, 2 Oct 2023 15:38:25 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, shuah@...nel.org, hughd@...gle.com,
swarupkotikalapudi@...il.com
Subject: Re: + selftests-proc-add-proc-pid-statm-output-validation.patch
added to mm-nonmm-unstable branch
On Sun, Oct 01, 2023 at 12:37:40PM -0700, Andrew Morton wrote:
> selftests-proc-add-proc-pid-statm-output-validation.patch
> Add /proc/${pid}/statm validation
>
> /proc/$(pid)/statm output is expected to be:
> "0 0 0 * 0 0 0\n"
> Here * can be any value
>
> Read output of /proc/$(pid)/statm
> and compare length of output is
> equal or greater than expected output
> --- a/tools/testing/selftests/proc/proc-empty-vm.c~selftests-proc-add-proc-pid-statm-output-validation
> +++ a/tools/testing/selftests/proc/proc-empty-vm.c
> @@ -303,6 +303,37 @@ static int test_proc_pid_smaps_rollup(pi
> }
> }
>
> +static const char g_statm[] = "0 0 0 * 0 0 0\n";
This is both unreliable and incorrect.
4th value is "end_code - start_code" when exec is done which could be
anything not 1-digit number (although unlikely).
Testing for strlen is simply too weak of a test.
> +static int test_proc_pid_statm(pid_t pid)
> +{
> + char buf[4096];
> +
> + snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
> +
> + int fd = open(buf, O_RDONLY);
> +
> + if (fd == -1) {
> + if (errno == ENOENT) {
> + /*
> + * /proc/${pid}/statm is under CONFIG_PROC_PAGE_MONITOR,
> + * it doesn't necessarily exist.
> + */
> + return EXIT_SUCCESS;
> + }
> + perror("open /proc/${pid}/statm");
> + return EXIT_FAILURE;
> + } else {
> + ssize_t rv = read(fd, buf, sizeof(buf));
> +
> + close(fd);
> + size_t len = strlen(g_statm);
> +
> + assert(rv >= len);
> + return EXIT_SUCCESS;
> + }
> +}
> +
> int main(void)
> {
> int rv = EXIT_SUCCESS;
> @@ -389,11 +420,8 @@ int main(void)
> if (rv == EXIT_SUCCESS) {
> rv = test_proc_pid_smaps_rollup(pid);
> }
> - /*
> - * TODO test /proc/${pid}/statm, task_statm()
> - * ->start_code, ->end_code aren't updated by munmap().
> - * Output can be "0 0 0 2 0 0 0\n" where "2" can be anything.
> - */
> + if (rv == EXIT_SUCCESS)
> + rv = test_proc_pid_statm(pid);
>
> /* Cut the rope. */
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