[merged mm-stable] mm-damon-core-handle-extreme-memory-state-in-get_node_memcg_used_bp.patch removed from -mm tree

[merged mm-stable] mm-damon-core-handle-extreme-memory-state-in-get_node_memcg_used_bp.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/damon/core: handle extreme memory state in get_node_memcg_used_bp()
has been removed from the -mm tree.  Its filename was
     mm-damon-core-handle-extreme-memory-state-in-get_node_memcg_used_bp.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 <sj@kernel.org>
Subject: mm/damon/core: handle extreme memory state in get_node_memcg_used_bp()
Date: Tue, 1 Sep 2026 06:18:48 -0700

In extreme unlikely situations, total memory might be zero.  In less
extreme but still very unlikely situations, lruvec_page_state() calls
might let the caller show used memory larger than total memory.  In the
two cases, damos_get_node_memcg_used_bp() could cause division by zero, or
return underflowed value, respectively.  Handle the cases by respectively
returning 100% and 0% for used and free memory queries in the corner
cases.

This issue was discovered [1] by Sashiko.

Link: https://lore.kernel.org/20260901131850.98037-8-sj@kernel.org
Link: https://lore.kernel.org/20260329154813.47382-1-sj@kernel.org [1]
Fixes: b74a120bcf50 ("mm/damon/core: implement DAMOS_QUOTA_NODE_MEMCG_USED_BP")
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: <stable@vger.kernel.org> # 6.19.x
---

 mm/damon/core.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/mm/damon/core.c~mm-damon-core-handle-extreme-memory-state-in-get_node_memcg_used_bp
+++ a/mm/damon/core.c
@@ -2857,6 +2857,12 @@ static unsigned long damos_get_node_memc
 	mem_cgroup_put(memcg);
 
 	si_meminfo_node(&i, goal->nid);
+	if (!i.totalram || i.totalram < used_pages) {
+		if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP)
+			return 10000;
+		else	/* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */
+			return 0;
+	}
 	if (goal->metric == DAMOS_QUOTA_NODE_MEMCG_USED_BP)
 		numerator = used_pages;
 	else	/* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */
_

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

mm-damon-core-use-damon_nr_samples_per_aggr-for-max-merge-threshold.patch
mm-damon-core-remove-debug-messages.patch
mm-damon-core-remove-debug-messages-fix.patch
mm-damon-vaddr-remove-a-debug-message.patch
mm-damon-core-validate-number-of-probes-in-valid_probe_params.patch
mm-damon-sysfs-remove-probes-number-validation.patch
mm-damon-tests-core-kunit-extend-set_regions-test-for-error-case.patch
mm-damon-tests-core-kunit-test-=0-size-damon_set_regions-inputs.patch
mm-damon-tests-core-kunit-test-overlapping-ranges-for-set_regions.patch
mm-damon-tests-core-kunit-test-damon_nr_samples_per_aggr.patch
selftests-damon-sysfssh-test-hugepage_mem_bp-quota-goal.patch
docs-mm-damon-maintainer-profile-update-ai-review-for-sashiko-replies.patch
docs-abi-damon-recommend-subsystem-doc-instead-of-admin-guide.patch
mm-damon-core-error-damos_commit_quota_goal-for-zero-target_value.patch
revert-mm-damon-lru_sort-error-out-for-10000-active_mem_bp.patch
revert-samples-damon-mtier-error-out-for-zero-quota-goal-target-values.patch
mm-damon-core-handle-null-ctx-parameter-in-damon_call.patch
mm-damon-core-set-ctx-call_controls_obsolete-in-damon_new_ctx.patch
mm-damon-reclaim-remove-unnecessary-damon_call-param-validation.patch
mm-damon-lru_sort-remove-unnecessary-damon_call-param-validation.patch
mm-damon-vaddr-support-prep_probes.patch
mm-damon-paddr-move-probe-filter-handling-to-ops-common.patch
mm-damon-vaddr-support-apply_probe.patch
mm-damon-vaddr-extend-apply_probes-for-hugetlb.patch
mm-damon-vaddr-support-pgidle_unset-probe-filter-type.patch
mm-damon-api-introduce-damon_filter_type_pgidle_set.patch
mm-damon-paddr-support-damon_filter_type_pgidle_set.patch
mm-damon-vaddr-support-damon_filter_type_pgidle_set.patch
mm-damon-sysfs-support-damon_filter_type_pgidle_set.patch
docs-mm-damon-design-update-for-pgidle_set-probe-filter.patch
mm-damon-api-introduce-damos_filter_type_probe_hits_wsum.patch
mm-damon-api-introduce-damos_filter_type_probe_hits_wsum-fix.patch
mm-damon-core-extend-probe_hits_wsum-for-moving-sum-based-calculation.patch
mm-damon-core-support-probe_hits_wsum-damos-core-filter.patch
mm-damon-sysfs-schemes-rename-sysfs_filter-sz_range-to-range_minmax.patch
mm-damon-sysfs-schemes-support-probe_hits_wsum-damos-core-filter.patch
docs-mm-damon-design-update-for-probe_hits_wsum-damos-core-filter.patch
docs-admin-guide-mm-damon-usage-update-for-probe_hits_wsum-damos-filter.patch
mm-damon-sysfs-schemes-read-sysfs_filter-addr_range-only-once.patch
mm-damon-sysfs-schemes-read-sysfs_filter-sz_range-only-once.patch
mm-damon-core-return-an-error-from-damos_commit_filter_arg.patch
mm-damon-core-disallow-max-min-damos-filter-range-arguments-commit.patch
mm-damon-sysfs-schemes-drop-centralized-filter-range-arg-validations.patch
mm-damon-sysfs-schemes-use-switch-case-in-add_scheme_filters.patch
mm-damon-core-kunit-extend-damos_commit_filter_for-for-wrong-input.patch
mm-damon-core-kunit-test-invalid-damos-filter-commits.patch
mm-damon-api-introduce-damon_filter_type_hugepage_size.patch
mm-damon-core-commit-hugepage_size-type-damon-filter.patch
mm-damon-ops-common-support-hugepage_size-damon-filter-matching.patch
mm-damon-sysfs-add-minmax-files-under-probe-filter-directory.patch
mm-damon-sysfs-support-hugepage_size-probe-filter.patch
docs-mm-damon-design-update-for-hugepage_size-probe-filter.patch
docs-admin-guide-mm-damon-usage-update-for-hugepage_size.patch
docs-abi-damon-update-for-hugepage_size-probe-filter.patch
mm-damon-api-remove-nr_damos_filter_types.patch
mm-damon-core-use-abs_diff-in-damon_feed_loop_next_input.patch
mm-damon-core-use-mult_frac-in-damon_feed_loop_next_input.patch
mm-damon-core-set-damon_ctx-walk_control_obsolete-in-damon_new_ctx.patch
mm-damon-core-document-damon_call-damon_start-race-hang-issue.patch
mm-damon-paddr-remove-pa-parameter-from-damon_pa_filter_pass.patch
mm-damon-tests-core-kunit-test-eligible_mem_bp-commitment.patch
mm-damon-tests-core-kunit-add-probe_hits_wsum-damos-filter-commit-test.patch
selftests-damon-sysfs_memcg_path_leak-fail-only-for-real-damon-leak.patch
docs-mm-damon-design-clarify-bp-is-basis-point.patch
mm-damon-core-introduce-damos_quota_goal-complement.patch
mm-damon-core-add-complement-argument-to-damos_new_quota_goal.patch
mm-damon-sysfs-schemes-support-quota-goal-complement-flag.patch
mm-damon-tests-core-kunit-test-quota_goal-complement-commit.patch
selftests-damon-sysfssh-test-quota-goal-complement-flag-file.patch
docs-mm-damon-design-document-damos-quota-goal-complement-flag.patch
docs-admin-guide-mm-damon-usage-update-for-quota-goal-complement-file.patch
docs-abi-damon-update-for-quota-goal-metric-complement-sysfs-file.patch