From: Andrew Morton <akpm@linux-foundation.org>
To: mm-commits@vger.kernel.org,stable@vger.kernel.org,sj@kernel.org,akpm@linux-foundation.org
Subject: + mm-damon-core-disallow-overlapping-input-ranges-for-damon_set_regions.patch added to mm-nonmm-unstable branch
Date: Sat, 04 Jul 2026 19:06:15 -0700 [thread overview]
Message-ID: <20260705020616.1B4AD1F000E9@smtp.kernel.org> (raw)
The patch titled
Subject: mm/damon/core: disallow overlapping input ranges for damon_set_regions()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
mm-damon-core-disallow-overlapping-input-ranges-for-damon_set_regions.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-disallow-overlapping-input-ranges-for-damon_set_regions.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: SJ Park <sj@kernel.org>
Subject: mm/damon/core: disallow overlapping input ranges for damon_set_regions()
Date: Fri, 3 Jul 2026 09:56:08 -0700
damon_set_regions() assumes the input ranges are sorted by the address and
don't overlap each other. Hence the assumption was initially to be
explicitly validated. But commit 97d482f4592f ("mm/damon/sysfs: reuse
damon_set_regions() for regions setting") has mistakenly removed the
validation.
This can make DAMON behave in unexpected ways. At the best, the
monitoring results snapshot will just look weird since there will be
overlapping regions. DAMOS will also work weirdly, applying the same
action multiple times for overlapping regions, and make DAMOS quota weird.
More seriously, depending on the setup and regions updates sequence,
negative size regions can be made. It will trigger WARN_ONCE() if the
kernel is built with CONFIG_DAMON_DEBUG_SANITY=y. Depending on the
monitoring results, the negative size region can further trigger division
by zero in damon_merge_two_regions().
Note that some of the consequences including the WARN_ONCE() and the
divide by zero depend on commits that were introduced after the root cause
commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for
regions setting").
Fix the problems by checking the assumption and returning an error if
the input ranges don't meet the assumption.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260703165610.92894-1-sj@kernel.org
Link: https://lore.kernel.org/20260630041806.151124-1-sj@kernel.org [1]
Fixes: 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/damon/core.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/mm/damon/core.c~mm-damon-core-disallow-overlapping-input-ranges-for-damon_set_regions
+++ a/mm/damon/core.c
@@ -441,12 +441,19 @@ int damon_set_regions(struct damon_targe
{
struct damon_region *r, *next;
unsigned int i;
+ unsigned long last_end;
int err;
for (i = 0; i < nr_ranges; i++) {
- if (ALIGN_DOWN(ranges[i].start, min_region_sz) >=
- ALIGN(ranges[i].end, min_region_sz))
+ unsigned long start, end;
+
+ start = ALIGN_DOWN(ranges[i].start, min_region_sz);
+ end = ALIGN(ranges[i].end, min_region_sz);
+ if (start >= end)
+ return -EINVAL;
+ if (i > 0 && last_end > start)
return -EINVAL;
+ last_end = end;
}
/* Remove regions which are not in the new ranges */
_
Patches currently in -mm which might be from sj@kernel.org are
maintainers-s-seongjae-sj.patch
mm-damon-core-validate-ranges-in-damon_set_regions.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
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-disallow-overlapping-input-ranges-for-damon_set_regions.patch
reply other threads:[~2026-07-05 2:06 UTC|newest]
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