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| author | SeongJae Park <sj@kernel.org> | 2024-09-05 19:24:23 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-09-10 02:39:14 +0300 |
| commit | 25e8acbcf19c56fbf0d80615c8f409586aabbf86 (patch) | |
| tree | 583f7208d2e78d4eaba119ec23f246fd1cbe3057 /mm/damon | |
| parent | 08e28de1160a712724268fd33d77b32f1bc84d1c (diff) | |
| download | linux-25e8acbcf19c56fbf0d80615c8f409586aabbf86.tar.xz | |
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/20240905162423.74053-1-sj@kernel.org
Fixes: 5e06ad590096 ("mm/damon/core-test: test max_nr_accesses overflow caused divide-by-zero")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Closes: https://lore.kernel.org/c771b962-a58f-435b-89e4-1211a9323181@roeck-us.net
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/damon')
| -rw-r--r-- | mm/damon/core.c | 8 | ||||
| -rw-r--r-- | mm/damon/tests/core-kunit.h | 12 |
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); } |