mm-damon-core-handle-zero-schemes-apply-interval.patch removed from -mm tree

The quilt patch titled
Subject: mm/damon/core: handle zero schemes apply interval
has been removed from the -mm tree. Its filename was
mm-damon-core-handle-zero-schemes-apply-interval.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: SeongJae Park <[email protected]>
Subject: mm/damon/core: handle zero schemes apply interval
Date: Thu, 31 Oct 2024 11:37:57 -0700

DAMON's logics to determine if this is the time to apply damos schemes assumes next_apply_sis is always set larger than current passed_sample_intervals. And therefore assume continuously incrementing passed_sample_intervals will make it reaches to the next_apply_sis in future. The logic hence does apply the scheme and update next_apply_sis only if passed_sample_intervals is same to next_apply_sis.

If Schemes apply interval is set as zero, however, next_apply_sis is set same to current passed_sample_intervals, respectively. And passed_sample_intervals is incremented before doing the next_apply_sis check. Hence, next_apply_sis becomes larger than next_apply_sis, and the logic says it is not the time to apply schemes and update next_apply_sis. In other words, DAMON stops applying schemes until passed_sample_intervals overflows.

Based on the documents and the common sense, a reasonable behavior for such inputs would be applying the schemes for every sampling interval. Handle the case by removing the assumption.

---

 mm/damon/core.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

@@ -1412,7 +1412,7 @@ static void damon_do_apply_schemes(struc
 	damon_for_each_scheme(s, c) {
 		struct damos_quota *quota = &s->quota;
 
-		if (c->passed_sample_intervals != s->next_apply_sis)
+		if (c->passed_sample_intervals < s->next_apply_sis)
 			continue;
 
 		if (!s->wmarks.activated)

@@ -1622,7 +1622,7 @@ static void kdamond_apply_schemes(struct
 	bool has_schemes_to_apply = false;
 
 	damon_for_each_scheme(s, c) {
-		if (c->passed_sample_intervals != s->next_apply_sis)
+		if (c->passed_sample_intervals < s->next_apply_sis)
 			continue;
 
 		if (!s->wmarks.activated)

@@ -1642,9 +1642,9 @@ static void kdamond_apply_schemes(struct
 	}
 
 	damon_for_each_scheme(s, c) {
-		if (c->passed_sample_intervals != s->next_apply_sis)
+		if (c->passed_sample_intervals < s->next_apply_sis)
 			continue;
-		s->next_apply_sis +=
+		s->next_apply_sis = c->passed_sample_intervals +
 			(s->apply_interval_us ? s->apply_interval_us :
 			 c->attrs.aggr_interval) / sample_interval;
 	}

_

Patches currently in -mm which might be from [email protected] are

selftests-damon-huge_count_read_write-remove-unnecessary-debugging-message.patch selftests-damon-_debugfs_common-hide-expected-error-message-from-test_write_result.patch selftests-damon-debugfs_duplicate_context_creation-hide-errors-from-expected-file-write-failures.patch mm-damon-kconfig-update-dbgfs_kunit-prompt-copy-for-sysfs_kunit.patch mm-damon-tests-dbgfs-kunit-fix-the-header-double-inclusion-guarding-ifdef-comment.patch docs-mm-damon-recommend-academic-papers-to-read-and-or-cite.patch maintainers-memory-management-add-document-files-for-mm.patch