Commit 6e79b375 authored by Swarup Laxman Kotiaklapudi's avatar Swarup Laxman Kotiaklapudi Committed by Andrew Morton
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proc: test /proc/${pid}/statm 

My original comment lied, output can be "0 A A B 0 0 0\n"
(see comment in the code).

I don't quite understand why

	get_mm_counter(mm, MM_FILEPAGES) + get_mm_counter(mm, MM_SHMEMPAGES)

can stay positive but get_mm_counter(mm, MM_ANONPAGES) is always 0 after
everything is unmapped but that's just me.

[adobriyan@gmail.com: more or less rewritten]
Link: https://lkml.kernel.org/r/0721ca69-7bb4-40aa-8d01-0c5f91e5f363@p183


Signed-off-by: default avatarSwarup Laxman Kotiaklapudi <swarupkotikalapudi@gmail.com>
Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 598f0ac1

tools/testing/selftests/proc/proc-empty-vm.c

+92 −5
Original line number Diff line number Diff line
@@ -303,6 +303,95 @@ static int test_proc_pid_smaps_rollup(pid_t pid) 
	}

}



static const char *parse_u64(const char *p, const char *const end, uint64_t *rv)

{

	*rv = 0;

	for (; p != end; p += 1) {

		if ('0' <= *p && *p <= '9') {

			assert(!__builtin_mul_overflow(*rv, 10, rv));

			assert(!__builtin_add_overflow(*rv, *p - '0', rv));

		} else {

			break;

		}

	}

	assert(p != end);

	return p;

}



/*

 * There seems to be 2 types of valid output:

 * "0 A A B 0 0 0\n" for dynamic exeuctables,

 * "0 0 0 B 0 0 0\n" for static executables.

 */

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) {

		perror("open /proc/${pid}/statm");

		return EXIT_FAILURE;

	}



	ssize_t rv = read(fd, buf, sizeof(buf));

	close(fd);



	assert(rv >= 0);

	assert(rv <= sizeof(buf));

	if (0) {

		write(1, buf, rv);

	}



	const char *p = buf;

	const char *const end = p + rv;



	/* size */

	assert(p != end && *p++ == '0');

	assert(p != end && *p++ == ' ');



	uint64_t resident;

	p = parse_u64(p, end, &resident);

	assert(p != end && *p++ == ' ');



	uint64_t shared;

	p = parse_u64(p, end, &shared);

	assert(p != end && *p++ == ' ');



	uint64_t text;

	p = parse_u64(p, end, &text);

	assert(p != end && *p++ == ' ');



	assert(p != end && *p++ == '0');

	assert(p != end && *p++ == ' ');



	/* data */

	assert(p != end && *p++ == '0');

	assert(p != end && *p++ == ' ');



	assert(p != end && *p++ == '0');

	assert(p != end && *p++ == '\n');



	assert(p == end);



	/*

	 * "text" is "mm->end_code - mm->start_code" at execve(2) time.

	 * munmap() doesn't change it. It can be anything (just link

	 * statically). It can't be 0 because executing to this point

	 * implies at least 1 page of code.

	 */

	assert(text > 0);



	/*

	 * These two are always equal. Always 0 for statically linked

	 * executables and sometimes 0 for dynamically linked executables.

	 * There is no way to tell one from another without parsing ELF

	 * which is too much for this test.

	 */

	assert(resident == shared);



	return EXIT_SUCCESS;

}



int main(void)

{

	int rv = EXIT_SUCCESS;
@@ -389,11 +478,9 @@ 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. */

		int wstatus;