selftests/mm: compaction_test: Fix bogus test success on Aarch64

Currently, if at runtime we are not able to allocate a huge page, the test will trivially pass on Aarch64 due to no exception being raised on division by zero while computing compaction_index. Fix that by checking for nr_hugepages == 0. Anyways, in general, avoid a division by zero by exiting the program beforehand. While at it, fix a typo.

Changes in v2:
- Combine with this series, handle unsigned long number of hugepages

Fixes bd67d5c15cc1 ("Test compaction of mlocked memory")

Cc [email protected]

Signed-off-by Dev Jain <[email protected]>

---
  tools/testing/selftests/mm/compaction_test.c | 20 +++++++++++++-------
  1 file changed, 13 insertions(+), 7 deletions(-)

tools/testing/selftests/mm/compaction_test.c +13 -7

index 4f42eb7d7636..0b249a06a60b 100644
@@ -82,12 +82,13 @@ int prereq(void)
  	return -1;
  }
 
-int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
+int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
  {
+	unsigned long nr_hugepages_ul;
  	int fd, ret = -1;
  	int compaction_index = 0;
-	char initial_nr_hugepages[10] = {0};
-	char nr_hugepages[10] = {0};
+	char initial_nr_hugepages[20] = {0};
+	char nr_hugepages[20] = {0};
 
  	/* We want to test with 80% of available memory. Else, OOM killer comes
  	   in to play */

@@ -134,7 +135,12 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 
  	/* We should have been able to request at least 1/3 rd of the memory in
  	   huge pages */
-	compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
+	nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
+	if (!nr_hugepages_ul) {
+		ksft_print_msg("ERROR: No memory is available as huge pages\n");
+		goto close_fd;
+	}
+	compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);
 
  	lseek(fd, 0, SEEK_SET);
 

@@ -145,11 +151,11 @@ int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
  		goto close_fd;
  	}
 
-	ksft_print_msg("Number of huge pages allocated = %d\n",
-		       atoi(nr_hugepages));
+	ksft_print_msg("Number of huge pages allocated = %lu\n",
+		       nr_hugepages_ul);
 
  	if (compaction_index > 3) {
-		ksft_print_msg("ERROR: Less that 1/%d of memory is available\n"
+		ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
  			       "as huge pages\n", compaction_index);
  		goto close_fd;
  	}