The patch titled
Subject: mm/damon/tests/core-kunit: skip damon_test_nr_accesses_to_accesses_bp() if aggr_interval is zero
has been added to the -mm mm-unstable branch. Its filename is
mm-damon-tests-core-kunit-skip-damon_test_nr_accesses_to_accesses_bp-if-aggr_interval-is-zero.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-tests-core-kunit-skip-damon_test_nr_accesses_to_accesses_bp-if-aggr_interval-is-zero.patch
This patch will later appear in the mm-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/tests/core-kunit: skip damon_test_nr_accesses_to_accesses_bp() if aggr_interval is zero
Date: Thu, 5 Sep 2024 09:24:23 -0700
The aggregation interval of test purpose damon_attrs for
damon_test_nr_accesses_to_accesses_bp() becomes zero on 32 bit
architecture, since size of int and long types are same. As a result,
damon_nr_accesses_to_accesses_bp() call with the test data triggers
divide-by-zero exception. damon_nr_accesses_to_accesses_bp() shouldn't
be called with such data, and the non-test code avoids that by checking
the case on damon_update_monitoring_results(). Skip the test code in
the case, and add an explicit caution of the case on the comment for the
test target function.
Link: https://lkml.kernel.org/r/20240905162423.74053-1-sj@xxxxxxxxxx
Fixes: 5e06ad590096 ("mm/damon/core-test: test max_nr_accesses overflow caused divide-by-zero")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Closes: https://lore.kernel.org/c771b962-a58f-435b-89e4-1211a9323181@xxxxxxxxxxxx
Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx>
Cc: David Gow <davidgow@xxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/damon/core.c | 8 +++++++-
mm/damon/tests/core-kunit.h | 12 ++++++++++++
2 files changed, 19 insertions(+), 1 deletion(-)
--- a/mm/damon/core.c~mm-damon-tests-core-kunit-skip-damon_test_nr_accesses_to_accesses_bp-if-aggr_interval-is-zero
+++ a/mm/damon/core.c
@@ -552,7 +552,13 @@ static unsigned int damon_accesses_bp_to
return accesses_bp * damon_max_nr_accesses(attrs) / 10000;
}
-/* convert nr_accesses to access ratio in bp (per 10,000) */
+/*
+ * Convert nr_accesses to access ratio in bp (per 10,000).
+ *
+ * Callers should ensure attrs.aggr_interval is not zero, like
+ * damon_update_monitoring_results() does . Otherwise, divide-by-zero would
+ * happen.
+ */
static unsigned int damon_nr_accesses_to_accesses_bp(
unsigned int nr_accesses, struct damon_attrs *attrs)
{
--- a/mm/damon/tests/core-kunit.h~mm-damon-tests-core-kunit-skip-damon_test_nr_accesses_to_accesses_bp-if-aggr_interval-is-zero
+++ a/mm/damon/tests/core-kunit.h
@@ -320,6 +320,18 @@ static void damon_test_nr_accesses_to_ac
.aggr_interval = ((unsigned long)UINT_MAX + 1) * 10
};
+ /*
+ * In some cases such as 32bit architectures where UINT_MAX is
+ * ULONG_MAX, attrs.aggr_interval becomes zero. Calling
+ * damon_nr_accesses_to_accesses_bp() in the case will cause
+ * divide-by-zero. Such case is prohibited in normal execution since
+ * the caution is documented on the comment for the function, and
+ * damon_update_monitoring_results() does the check. Skip the test in
+ * the case.
+ */
+ if (!attrs.aggr_interval)
+ kunit_skip(test, "aggr_interval is zero.");
+
KUNIT_EXPECT_EQ(test, damon_nr_accesses_to_accesses_bp(123, &attrs), 0);
}
_
Patches currently in -mm which might be from sj@xxxxxxxxxx are
mm-damon-core-intorduce-per-context-region-priorities-histogram-buffer.patch
mm-damon-core-replace-per-quota-regions-priority-histogram-buffer-usage-with-per-context-one.patch
mm-damon-core-remove-per-scheme-region-priority-histogram-buffer.patch
revert-mm-damon-lru_sort-adjust-local-variable-to-dynamic-allocation.patch
docs-damon-use-damonitor-github-organization-instead-of-awslabs.patch
docs-damon-maintainer-profile-add-links-in-place.patch
docs-damon-maintainer-profile-document-google-calendar-for-bi-weekly-meetups.patch
mm-damon-tests-vaddr-kunit-init-maple-tree-without-mt_flags_lock_extern.patch
mm-damon-tests-core-kunit-skip-damon_test_nr_accesses_to_accesses_bp-if-aggr_interval-is-zero.patch
