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Date: Mon, 9 Oct 2023 14:07:14 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
Shuah Khan <shuah@...nel.org>
Subject: [PATCH v3] proc: test /proc/${pid}/statm
From: Swarup Laxman Kotiaklapudi <swarupkotikalapudi@...il.com>
[more or less rewritten. --adobriyan]
My original comment lied, output can be "0 A A B 0 0 0\n"
(see comment in the code).
I don't quite understand why
get_mm_counter(mm, MM_FILEPAGES) + get_mm_counter(mm, MM_SHMEMPAGES)
can stay positive but get_mm_counter(mm, MM_ANONPAGES) is always 0 after
everything is unmapped but that's just me.
Signed-off-by: Swarup Laxman Kotiaklapudi <swarupkotikalapudi@...il.com>
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
tools/testing/selftests/proc/proc-empty-vm.c | 97 +++++++++++++++++++++++++--
1 file changed, 92 insertions(+), 5 deletions(-)
--- a/tools/testing/selftests/proc/proc-empty-vm.c
+++ b/tools/testing/selftests/proc/proc-empty-vm.c
@@ -303,6 +303,95 @@ static int test_proc_pid_smaps_rollup(pid_t pid)
}
}
+static const char *parse_u64(const char *p, const char *const end, uint64_t *rv)
+{
+ *rv = 0;
+ for (; p != end; p += 1) {
+ if ('0' <= *p && *p <= '9') {
+ assert(!__builtin_mul_overflow(*rv, 10, rv));
+ assert(!__builtin_add_overflow(*rv, *p - '0', rv));
+ } else {
+ break;
+ }
+ }
+ assert(p != end);
+ return p;
+}
+
+/*
+ * There seems to be 2 types of valid output:
+ * "0 A A B 0 0 0\n" for dynamic exeuctables,
+ * "0 0 0 B 0 0 0\n" for static executables.
+ */
+static int test_proc_pid_statm(pid_t pid)
+{
+ char buf[4096];
+ snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
+ int fd = open(buf, O_RDONLY);
+ if (fd == -1) {
+ perror("open /proc/${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;
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