The patch titled
Subject: mm/damon/core: handle zero schemes apply interval
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-damon-core-handle-zero-schemes-apply-interval.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-handle-zero-schemes-apply-interval.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
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.
Link: https://lkml.kernel.org/r/20241031183757.49610-3-sj@xxxxxxxxxx
Fixes: 42f994b71404 ("mm/damon/core: implement scheme-specific apply interval")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [6.7.x]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/damon/core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/damon/core.c~mm-damon-core-handle-zero-schemes-apply-interval
+++ a/mm/damon/core.c
@@ -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 sj@xxxxxxxxxx are
mm-damon-core-handle-zero-aggregationops_update-intervals.patch
mm-damon-core-handle-zero-schemes-apply-interval.patch
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
