selftests/vm: dedup THP helpers

These files:

tools/testing/selftests/vm/vm_util.c
tools/testing/selftests/vm/khugepaged.c

Both contain logic to:

1) Determine hugepage size on current system
2) Read /proc/self/smaps to determine number of THPs at an address

Refactor selftests/vm/khugepaged.c to use the vm_util common helpers and
add it as a build dependency.

Since selftests/vm/khugepaged.c is the largest user of check_huge(),
change the signature of check_huge() to match selftests/vm/khugepaged.c's
useage: take an expected number of hugepages, and return a bool indicating
if the correct number of hugepages were found.  Add a wrapper,
check_huge_anon(), in anticipation of checking smaps for file and shmem
hugepages.

Update existing callsites to use the new pattern / function.

Likewise, check_for_pattern() was duplicated, and it's a general enough
helper to include in vm_util helpers as well.

Link: https://lkml.kernel.org/r/20220907144521.3115321-6-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220922224046.1143204-6-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 17 insertions, 9 deletions

diff --git a/tools/testing/selftests/vm/vm_util.c b/tools/testing/selftests/vm/vm_util.c
index b58ab11a7a30..9dae51b8219f 100644
--- a/tools/testing/selftests/vm/vm_util.c
+++ b/tools/testing/selftests/vm/vm_util.c
@@ -42,9 +42,9 @@ void clear_softdirty(void)
 		ksft_exit_fail_msg("writing clear_refs failed\n");
 }
 
-static bool check_for_pattern(FILE *fp, const char *pattern, char *buf)
+bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
 {
-	while (fgets(buf, MAX_LINE_LENGTH, fp) != NULL) {
+	while (fgets(buf, len, fp)) {
 		if (!strncmp(buf, pattern, strlen(pattern)))
 			return true;
 	}
@@ -72,9 +72,10 @@ uint64_t read_pmd_pagesize(void)
 	return strtoul(buf, NULL, 10);
 }
 
-uint64_t check_huge(void *addr)
+bool __check_huge(void *addr, char *pattern, int nr_hpages,
+		  uint64_t hpage_size)
 {
-	uint64_t thp = 0;
+	uint64_t thp = -1;
 	int ret;
 	FILE *fp;
 	char buffer[MAX_LINE_LENGTH];
@@ -89,20 +90,27 @@ uint64_t check_huge(void *addr)
 	if (!fp)
 		ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, SMAP_FILE_PATH);
 
-	if (!check_for_pattern(fp, addr_pattern, buffer))
+	if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer)))
 		goto err_out;
 
 	/*
-	 * Fetch the AnonHugePages: in the same block and check the number of
+	 * Fetch the pattern in the same block and check the number of
 	 * hugepages.
 	 */
-	if (!check_for_pattern(fp, "AnonHugePages:", buffer))
+	if (!check_for_pattern(fp, pattern, buffer, sizeof(buffer)))
 		goto err_out;
 
-	if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) != 1)
+	snprintf(addr_pattern, MAX_LINE_LENGTH, "%s%%9ld kB", pattern);
+
+	if (sscanf(buffer, addr_pattern, &thp) != 1)
 		ksft_exit_fail_msg("Reading smap error\n");
 
 err_out:
 	fclose(fp);
-	return thp;
+	return thp == (nr_hpages * (hpage_size >> 10));
+}
+
+bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size)
+{
+	return __check_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size);
 }