[merged mm-stable] samples-damon-mtier-handle-damon_start-failure.patch removed from -mm tree

The quilt patch titled
     Subject: samples/damon/mtier: handle damon_start() failure
has been removed from the -mm tree.  Its filename was
     samples-damon-mtier-handle-damon_start-failure.patch

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

------------------------------------------------------
From: SJ Park <[email protected]>
Subject: samples/damon/mtier: handle damon_start() failure
Date: Sun, 28 Jun 2026 14:54:42 -0700

damon_sample_mtier_start() callers assume it will clean up resources when
it fails.  And the function does the cleanup for context buildup failures.
However, it is not doing the cleanup for damon_start() failure.

As a result, when damon_start() fails, it could leak the memory for DAMON
context.  Also, if damon_start() fails for only the second context, the
first context will indefinitely run, and avoid starting other DAMON
contexts since it is running in the exclusive mode.  Stop possibly started
DAMON context and free the contexts in case of the failure to fix the
issues.

Note that the issue can reliably be reproduced because the module calls
damon_start() in the exclusive mode.  For example,

    $ sudo damo start
    $ echo Y | sudo tee /sys/module/damon_sample_mtier/parameters/enabled
    $ sudo cat /proc/allocinfo | grep damon_new_ctx

Because the first command is running another DAMON instance, the second
command fails the damon_start() call because the new DAMON instance cannot
exclusively run.  And without this fix, by repeating the second and the
third commands above, we can show the memory consumption is only
increasing due to the leaks.  It requires the sudo permission though.

The issue was discovered [1] by Sashiko.

Link: https://lore.kernel.org/[email protected]
Link: https://lore.kernel.org/[email protected] [1]
Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: SJ Park <[email protected]>
Reviewed-by: Zenghui Yu <[email protected]>
Cc: <[email protected]> # 6.16.x
Signed-off-by: Andrew Morton <[email protected]>
---

 samples/damon/mtier.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/samples/damon/mtier.c~samples-damon-mtier-handle-damon_start-failure
+++ a/samples/damon/mtier.c
@@ -177,6 +177,7 @@ free_out:
 static int damon_sample_mtier_start(void)
 {
 	struct damon_ctx *ctx;
+	int err;
 
 	ctx = damon_sample_mtier_build_ctx(true);
 	if (!ctx)
@@ -188,7 +189,15 @@ static int damon_sample_mtier_start(void
 		return -ENOMEM;
 	}
 	ctxs[1] = ctx;
-	return damon_start(ctxs, 2, true);
+	err = damon_start(ctxs, 2, true);
+	if (!err)
+		return 0;
+
+	if (damon_is_running(ctxs[0]))
+		damon_stop(ctxs, 1);
+	damon_destroy_ctx(ctxs[0]);
+	damon_destroy_ctx(ctxs[1]);
+	return err;
 }
 
 static void damon_sample_mtier_stop(void)
_

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

mm-damon-adjust-isolated-pages-stat-for-damos_migrate_hotcold.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
mm-damon-add-damon_region-last_probe_hits.patch
mm-damon-core-introduce-damon_probe_hits_mvsum.patch
mm-damon-sysfs-schemes-set-probe-hits-as-pseudo-moving-sums.patch
mm-damon-core-safely-validate-src-on-damon_commit_ctx.patch
mm-damon-core-do-parameter-testing-commit-on-damon_start.patch
mm-damon-sysfs-remove-duplicated-commit-input-validity-check.patch
mm-damon-reclaim-remove-duplicated-min_region_sz-power-of-2-check.patch
mm-damon-lru_sort-remove-duplicated-min_region_sz-power_of_2-check.patch
mm-damon-document-region-size-validation-in-damon_set_regions.patch
mm-damon-core-remove-start-end-check-in-damon_set_region_system_rams.patch
mm-damon-sysfs-remove-region-size-validation.patch
mm-damon-core-stop-ctxs-in-damon_start-before-returning-an-error.patch
samples-damon-mtier-do-not-stop-first-context-for-damon_start-failure.patch
mm-damon-core-make-damon_stop-never-fails.patch
mm-damon-sysfs-ignore-damon_stop-return-value.patch
mm-damon-reclaaim-ignore-damon_stop-return-value.patch
mm-damon-lru_sort-ignore-damon_stop-return-value.patch
mm-damon-core-change-damon_stop-return-type-to-void.patch
samples-damon-mtier-stop-all-contexts-with-single-damon_stop-call.patch
mm-damon-core-wait-ctx-stop-in-damon_call-before-reruning-an-error.patch
samples-damon-wsse-do-not-stop-ctx-for-damon_call-failure.patch
samples-damon-prcl-do-not-stop-damon-for-damon_call-failure.patch
mm-damon-core-remove-comment-and-test-for-nr_to_bp-divide-by-zero.patch
mm-damon-core-s-damon_max_nr_accesses-damon_nr_samples_per_aggr.patch
mm-damon-core-s-accesses_bp_to_nr_accesses-sample_bp_to_count.patch
mm-damon-core-s-nr_accesses_to_accesses_bp-sample_count_to_bp.patch
mm-damon-core-s-nr_accesses_for_new_attrs-nr_samples_for_new_attrs.patch
mm-damon-core-update-probe-hits-for-new-parameter-commit.patch
mm-damon-core-handle-unreset-probe_hits-in-probe_hits_mvsum.patch
mm-damon-core-introduce-damon_probe-weight.patch
mm-damon-core-ask-apply_probes-ops-callback-to-set-sampling-address.patch
mm-damon-paddr-set-samples-in-apply_probes-if-requested.patch
mm-damon-core-ask-apply_probe-to-return-max-probe-hits-weighted-sum.patch
mm-damon-core-implement-damon_probe_hits_wsum.patch
mm-damon-paddr-respect-return_max_wsum.patch
mm-damon-core-use-abs_diff-instead-of-abs.patch
mm-damon-core-extend-merge-function-to-work-with-probe-hits.patch
mm-damon-core-disallow-probe_hits-overflow-on-attrs-only-monitoring.patch
mm-damon-core-validate-params-for-probe-hits-weighted-sum-overflow.patch
mm-damon-core-disable-access-monitoring-when-probe-weights-are-set.patch
mm-damon-core-set-samples-in-apply_probes-if-probe-weights-are-set.patch
mm-damon-core-s-max_nr_accesses-max_merge_score-in-kdamond_fn.patch
mm-damon-core-get-merge-threshold-from-probe-hits-when-weights-are-set.patch
mm-damon-core-implement-damon_has_probe_weight.patch
mm-damon-sysfs-implement-probe-weight-file.patch
docs-mm-damon-design-document-attrs-only-monitoring.patch
docs-admin-guide-mm-damon-usage-document-weight-sysfs-file.patch
docs-abi-damon-document-probe-weight-file.patch
mm-damon-core-skip-aging-from-repeated-aggressive-merging.patch
mm-damon-core-hide-private-damon_region-fields.patch
mm-damon-core-hide-private-damon_target-fields.patch
mm-damon-core-hide-private-damos_quota_goal-fields.patch
mm-damon-core-hide-private-damos_quota-fields.patch
mm-damon-core-hide-private-damos_filter-fields.patch
mm-damon-core-hide-private-damos-fields.patch
mm-damon-core-hide-private-damon_filter-fields.patch
mm-damon-core-hide-private-damon_probe-fields.patch
mm-damon-sysfs-do-not-directly-access-damon_ctx-ops.patch
mm-damon-core-hide-core-private-damon_ctx-fields.patch
mm-damon-core-avoid-infinite-kdamond_merge_regions-internal-loop.patch
mm-damon-tests-core-kunit-catch-test-failure-in-test_merge_regions_of.patch
mm-damon-vaddr-drop-last-same-folio-access-check-optimization.patch
mm-damon-paddr-drop-last-same-folio-access-check-reuse-optimization.patch
mm-damon-sysfs-read-addr_unit-only-once-in-damon_sysfs_apply_inputs.patch
mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch
mm-damon-core-initialize-damos-last_applied.patch
mm-damon-core-kunit-check-region-count-before-testing-in-split_at.patch
mm-damon-vaddr-kunit-check-region-count-in-three_regions-test.patch
mm-damon-core-kunit-handle-region-split-failure-in-filter_out.patch
mm-damon-core-kunit-skip-wrong-dest-walk-in-commit_dests_for.patch
mm-damon-core-kunit-skip-wrong-quota-goal-walk-in-commit_quota_goals.patch
mm-damon-core-kunit-skip-wrong-region-walk-in-commit_target_regions.patch
mm-damon-ops-common-use-nr_accesses-moving-sum-for-quota-score.patch
mm-damon-core-handle-region-split-failure-in-apply_min_nr_regions.patch