+ mm-damon-core-handle-unreset-nr_accesses-in-damon_nr_accesses_mvsum.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/damon/core: handle unreset nr_accesses in damon_nr_accesses_mvsum()
has been added to the -mm mm-new branch.  Its filename is
     mm-damon-core-handle-unreset-nr_accesses-in-damon_nr_accesses_mvsum.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-unreset-nr_accesses-in-damon_nr_accesses_mvsum.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: SJ Park <sj@kernel.org>
Subject: mm/damon/core: handle unreset nr_accesses in damon_nr_accesses_mvsum()
Date: Mon, 29 Jun 2026 21:07:57 -0700

damon_set_attrs() works like reverting aggregations that were made so far
for this aggregation window.  If this is the end of the aggregation,
however, kdamond_fn() will do the operations at the end of the aggregation
interval, using cached timestamps.  For such operations that rely on
damon_region->nr_accesses, damon_update_monitoring_results() doesn't reset
the nr_accesses if it is called at the end of the aggregation window.

damon_nr_accesses_mvsum() works with fresh timestamps, though.  The
nr_accesses that are not reset in this case can make the logic to
unnecessarily count nr_accesses, resulting in returning
higher-than-expected pseudo moving sum nr_accesses.  No code is using
damon_nr_accesses_mvsum() yet, so this is not causing a real problem. 
Following commits will add usage of the function, though.  For safe
usages, calculate the pseudo moving sum without nr_accesses if the
remaining window is full.

Link: https://lore.kernel.org/20260630040812.149729-5-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/core.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/damon/core.c~mm-damon-core-handle-unreset-nr_accesses-in-damon_nr_accesses_mvsum
+++ a/mm/damon/core.c
@@ -266,6 +266,9 @@ unsigned int damon_nr_accesses_mvsum(str
 			ctx->passed_sample_intervals;
 	left_window_bp = mult_frac(left_window, 10000, window_len);
 
+	if (left_window_bp == 10000)
+		return r->last_nr_accesses;
+
 	return damon_mvsum(r->nr_accesses, r->last_nr_accesses,
 			left_window_bp);
 }
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-sysfs-schemes-fix-dir-put-orders-in-access_pattern_add_dirs.patch
mm-damon-sysfs-schemes-put-stats-for-scheme_add_dirs-internal-error.patch
mm-damon-ops-common-handle-extreme-intervals-in-damon_hot_score.patch
mm-damon-add-a-kernel-doc-comment-for-damon_ctx-probes.patch
mm-damon-add-a-kernel-doc-comment-for-damon_ctx-rnd_state.patch
maintainers-s-seongjae-sj.patch
samples-damon-wsse-handle-damon_start-failure.patch
samples-damon-prcl-handle-damon_start-failure.patch
samples-damon-mtier-handle-damon_start-failure.patch
samples-damon-mtier-handle-damon_stop-failure.patch
samples-damon-wsse-stop-and-free-damon-ctx-when-damon_call-fails.patch
samples-damon-prcl-stop-and-free-damon-ctx-when-damon_call-fails.patch
mm-damon-sysfs-kobject_del-target-normal-context-and-kdamond-dirs.patch
mm-damon-sysfs-kobject_del-region-and-target-error-dirs.patch
mm-damon-sysfs-schemes-kobject_del-scheme-dirs.patch
mm-damon-sysfs-schemes-kobject_del-scheme-region-dirs.patch
mm-damon-sysfs-schemes-kobject_del-scheme-filter-dirs.patch
mm-damon-sysfs-schemes-kobject_del-scheme-quota-goal-dirs.patch
mm-damon-sysfs-schemes-kobject_del-scheme-action-destination-dirs.patch
mm-damon-sysfs-kobject_del-probe-dirs.patch
mm-damon-sysfs-kobject_del-probe-filter-dirs.patch
mm-damon-sysfs-kobject_del-probe-dirs-in-probes_addd_dir-error-path.patch
mm-damon-sysfs-schemes-kobject_del-region-for-populate_region-error.patch
docs-mm-damon-design-update-for-damos_quota_node_eligible_mem_bp.patch
docs-abi-damon-document-probe-files.patch
mm-damon-tests-core-kunit-test-damon_rand.patch
selftests-damon-sysfssh-test-multiple-probe-dirs-creation.patch
selftests-damon-sysfssh-test-coreops_filters-directories.patch
selftests-damon-sysfssh-test-dests-dir.patch
selftests-damon-sysfssh-test-all-files-in-quota-goal-dir.patch
mm-damon-core-reduce-range-setup-in-damon_commit_target_regions.patch
mm-damon-sysfs-split-probe-setup-function-out.patch
mm-damon-sysfs-split-out-filters-setup-function.patch
mm-damon-sysfs-fix-typos-in-probe_addrm_dirs-s-attr-probe.patch
mm-damon-core-introduce-damon_nr_accesses_mvsum.patch
mm-damon-tests-core-kunit-test-damon_mvsum.patch
mm-damon-core-always-update-last_nr_accesses-for-intervals-change.patch
mm-damon-core-handle-unreset-nr_accesses-in-damon_nr_accesses_mvsum.patch
mm-damon-core-use-damon_nr_accesses_mvsum-in-__damos_valid_target.patch
mm-damon-core-use-damon_nr_accesses_mvsum-for-damos-region-tracing.patch
mm-damon-sysfs-schemes-use-damon_nr_accesses_mvsum-for-damo-regions.patch
mm-damon-core-remove-damon_warn_fix_nr_accesses_corruption.patch
mm-damon-core-remove-damon_verify_reset_aggregated.patch
mm-damon-core-remove-damon_verify_merge_regions_of.patch
mm-damon-tests-core-kunit-remove-nr_accesses_bp-setup-and-tests.patch
selftests-damon-drgn_dump_damon_status-do-not-dump-nr_accesses_bp.patch
mm-damon-core-remove-nr_accesses_bp-setups-and-updates.patch
mm-damon-core-remove-attrs-param-from-damon_update_region_access_rate.patch
mm-damon-paddr-remove-attrs-param-from-__damon_pa_check_access.patch
mm-damon-vaddr-remove-attrs-param-from-__damon_va_check_access.patch
mm-damon-core-remove-damon_moving_sum-and-its-unit-test.patch
mm-damon-core-remove-damon_region-nr_accesses_bp.patch