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authorSeongJae Park <[email protected]>2024-09-05 09:24:23 -0700
committerAndrew Morton <[email protected]>2024-09-09 16:39:14 -0700
commit25e8acbcf19c56fbf0d80615c8f409586aabbf86 (patch)
tree583f7208d2e78d4eaba119ec23f246fd1cbe3057
parent08e28de1160a712724268fd33d77b32f1bc84d1c (diff)
mm/damon/tests/core-kunit: skip damon_test_nr_accesses_to_accesses_bp() if aggr_interval is zero
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/[email protected] Fixes: 5e06ad590096 ("mm/damon/core-test: test max_nr_accesses overflow caused divide-by-zero") Signed-off-by: SeongJae Park <[email protected]> Reported-by: Guenter Roeck <[email protected]> Closes: https://lore.kernel.org/[email protected] Cc: Brendan Higgins <[email protected]> Cc: David Gow <[email protected]> Cc: Guenter Roeck <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
-rw-r--r--mm/damon/core.c8
-rw-r--r--mm/damon/tests/core-kunit.h12
2 files changed, 19 insertions, 1 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 8b99c5a99c38..a83f3b736d51 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -552,7 +552,13 @@ static unsigned int damon_accesses_bp_to_nr_accesses(
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)
{
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index ae03df71737e..cf22e09a3507 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -320,6 +320,18 @@ static void damon_test_nr_accesses_to_accesses_bp(struct kunit *test)
.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);
}