Hi Jinjie,
Thank you for this patchset!
On Mon, 18 Sep 2023 13:10:43 +0800 Jinjie Ruan <ruanjinjie@xxxxxxxxxx> wrote:
> The damon_region which is allocated by kmem_cache_alloc() in
> damon_new_region() in damon_test_regions() and
> damon_test_update_monitoring_result() are not freed and it causes below
> memory leak. So use damon_free_region() to free it.
>
> unreferenced object 0xffff2b49c3edc000 (size 56):
> comm "kunit_try_catch", pid 338, jiffies 4294895280 (age 557.084s)
> hex dump (first 32 bytes):
> 01 00 00 00 00 00 00 00 02 00 00 00 00 00 00 00 ................
> 00 00 00 00 00 00 00 00 00 00 00 00 49 2b ff ff ............I+..
> backtrace:
> [<0000000088e71769>] slab_post_alloc_hook+0xb8/0x368
> [<00000000b528f67c>] kmem_cache_alloc+0x168/0x284
> [<000000008603f022>] damon_new_region+0x28/0x54
> [<00000000a3b8c64e>] damon_test_regions+0x38/0x270
> [<00000000559c4801>] kunit_try_run_case+0x50/0xac
> [<000000003932ed49>] kunit_generic_run_threadfn_adapter+0x20/0x2c
> [<000000003c3e9211>] kthread+0x124/0x130
> [<0000000028f85bdd>] ret_from_fork+0x10/0x20
> unreferenced object 0xffff2b49c5b20000 (size 56):
> comm "kunit_try_catch", pid 354, jiffies 4294895304 (age 556.988s)
> hex dump (first 32 bytes):
> 03 00 00 00 00 00 00 00 07 00 00 00 00 00 00 00 ................
> 00 00 00 00 00 00 00 00 96 00 00 00 49 2b ff ff ............I+..
> backtrace:
> [<0000000088e71769>] slab_post_alloc_hook+0xb8/0x368
> [<00000000b528f67c>] kmem_cache_alloc+0x168/0x284
> [<000000008603f022>] damon_new_region+0x28/0x54
> [<00000000ca019f80>] damon_test_update_monitoring_result+0x18/0x34
> [<00000000559c4801>] kunit_try_run_case+0x50/0xac
> [<000000003932ed49>] kunit_generic_run_threadfn_adapter+0x20/0x2c
> [<000000003c3e9211>] kthread+0x124/0x130
> [<0000000028f85bdd>] ret_from_fork+0x10/0x20
Nice finding! Could you please share just a brief more detail about above cool
output, e.g., just the name of the tool you used, so that others can learn it
from your awesome commit message?
>
> Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
> Fixes: f4c978b6594b ("mm/damon/core-test: add a test for damon_update_monitoring_results()")
> Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
> ---
> mm/damon/core-test.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/damon/core-test.h b/mm/damon/core-test.h
> index 6cc8b245586d..255f8c925c00 100644
> --- a/mm/damon/core-test.h
> +++ b/mm/damon/core-test.h
> @@ -34,6 +34,7 @@ static void damon_test_regions(struct kunit *test)
> KUNIT_EXPECT_EQ(test, 0u, damon_nr_regions(t));
>
> damon_free_target(t);
> + damon_free_region(r);
There is damon_destroy_region() function, which simply calls damon_del_region()
and damon_free_region(). Unless there is needs to access the region before
removing from the region, doing memory return together via the function is
recommended.
And this test code calls damon_del_region() just beofre above
KUNIT_EXPECT_EQ(). Hence, I think replacing the damon_del_region() call with
damon_destroy_region() rather than calling damon_free_region() may be simpler
and shorter. Could you please do so?
> }
>
> static unsigned int nr_damon_targets(struct damon_ctx *ctx)
> @@ -316,6 +317,8 @@ static void damon_test_update_monitoring_result(struct kunit *test)
> damon_update_monitoring_result(r, &old_attrs, &new_attrs);
> KUNIT_EXPECT_EQ(test, r->nr_accesses, 150);
> KUNIT_EXPECT_EQ(test, r->age, 20);
> +
> + damon_free_region(r);
This looks nice. Thank you for fixing this!
> }
>
> static void damon_test_set_attrs(struct kunit *test)
> --
> 2.34.1
>
Thanks,
SJ
