[PATCH 1/1] selftests/proc: use RSS in /proc/pid/smaps_rollup tearing tests

[Suren Baghdasaryan]

Pss metrics can be affected by map count even if VMA tree stays unchanged,
therefore test checking VMA tree integrity can't use them. Use Rss instead
and pre-populate the VMAs so that Rss changes if a VMA gets skipped or
double-counted.

Fixes: ca5480fb53fa ("selftests/proc: add /proc/pid/smaps_rollup tearing tests")
Reported-by: kernel test robot <yi1.lai@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202610271934.fd287c3f-lkp@xxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
 tools/testing/selftests/proc/proc-maps-race.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/proc/proc-maps-race.c b/tools/testing/selftests/proc/proc-maps-race.c
index bf4c5073f6fc..b6d88afb252b 100644
--- a/tools/testing/selftests/proc/proc-maps-race.c
+++ b/tools/testing/selftests/proc/proc-maps-race.c
@@ -528,13 +528,10 @@ static bool compare_smaps_rollup(FIXTURE_DATA(proc_maps_race) *self,
 		struct smaps_rollup_stats *actual)
 {
 	/*
-	 * Clean/dirty metrics might change but Pss-related ones
-	 * should stay constant.
+	 * Clean/dirty metrics might change. Pss depends on map count and might
+	 * change as well. Rss should stay constant.
 	 */
-	if (cmp_smaps_rollup_stat(expected, actual, Pss) &&
-	    cmp_smaps_rollup_stat(expected, actual, Pss_Anon) &&
-	    cmp_smaps_rollup_stat(expected, actual, Pss_File) &&
-	    cmp_smaps_rollup_stat(expected, actual, Pss_Shmem))
+	if (cmp_smaps_rollup_stat(expected, actual, Rss))
 		return true;
 
 	print_smaps_rollup_stats("Expected stats:", self, expected);
@@ -759,7 +756,7 @@ FIXTURE_SETUP(proc_maps_race)
 
 		for (i = 0; i < mod_info->vma_count; i++) {
 			mod_info->child_mapped_addr[i] = mmap(NULL, self->page_size * 3, prot,
-					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+					MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
 			ASSERT_NE(mod_info->child_mapped_addr[i], MAP_FAILED);
 			/* change protection in adjacent maps to prevent merging */
 			prot ^= PROT_WRITE;

base-commit: 39274b454e9993cea319f4ac342a8082a9ee1730
-- 
2.56.0.307.g5fe7bd680c-goog