Re: [PATCH RESEND 2/2] mm/damon/core-test: Fix memory leak in damon_new_ctx()

[Ruan Jinjie <ruanjinjie@huawei.com>]

On 2023/9/18 13:43, SeongJae Park wrote:
> Hi Jinjie,
> 
> On Mon, 18 Sep 2023 13:10:44 +0800 Jinjie Ruan <ruanjinjie@huawei.com> wrote:
> 
>> The damon_ctx which is allocated by kzalloc() in damon_new_ctx() in
>> damon_test_ops_registration() and damon_test_set_attrs() are not freed and
>> it causes below memory leak. So use damon_destroy_ctx() to free it.
>>
>> unreferenced object 0xffff2b49c6968800 (size 512):
>>   comm "kunit_try_catch", pid 350, jiffies 4294895294 (age 557.028s)
>>   hex dump (first 32 bytes):
>>     88 13 00 00 00 00 00 00 a0 86 01 00 00 00 00 00  ................
>>     00 87 93 03 00 00 00 00 0a 00 00 00 00 00 00 00  ................
>>   backtrace:
>>     [<0000000088e71769>] slab_post_alloc_hook+0xb8/0x368
>>     [<0000000073acab3b>] __kmem_cache_alloc_node+0x174/0x290
>>     [<00000000b5f89cef>] kmalloc_trace+0x40/0x164
>>     [<00000000eb19e83f>] damon_new_ctx+0x28/0xb4
>>     [<00000000daf6227b>] damon_test_ops_registration+0x34/0x328
>>     [<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 0xffff2b49c1a9cc00 (size 512):
>>   comm "kunit_try_catch", pid 356, jiffies 4294895306 (age 557.000s)
>>   hex dump (first 32 bytes):
>>     88 13 00 00 00 00 00 00 a0 86 01 00 00 00 00 00  ................
>>     00 00 00 00 00 00 00 00 0a 00 00 00 00 00 00 00  ................
>>   backtrace:
>>     [<0000000088e71769>] slab_post_alloc_hook+0xb8/0x368
>>     [<0000000073acab3b>] __kmem_cache_alloc_node+0x174/0x290
>>     [<00000000b5f89cef>] kmalloc_trace+0x40/0x164
>>     [<00000000eb19e83f>] damon_new_ctx+0x28/0xb4
>>     [<00000000058495c4>] damon_test_set_attrs+0x30/0x1a8
>>     [<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
> 
> Same to the comment on the first patch of this patchset, simply letting others
> know the name of the tool you used for making this cool output could be
> helpful.  Could you please add it?
> 
> Also, I prefer adding four spaces indent to quoted command outputs on commit
> messages.  Could you please add that indentation?
> 
> Also, I cannot 'git am' this patch on top of mm-unstable[1].  Could you please
> double check and rebase on latest mm-unstable if I din't miss something?
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/log/?h=mm-unstable

Sure. Thank you very much!

> 
>>
>> Fixes: d1836a3b2a9a ("mm/damon/core-test: initialise context before test in damon_test_set_attrs()")
>> Fixes: 4f540f5ab4f2 ("mm/damon/core-test: add a kunit test case for ops registration")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>  mm/damon/core-test.h | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/mm/damon/core-test.h b/mm/damon/core-test.h
>> index 255f8c925c00..ce86ed30fb47 100644
>> --- a/mm/damon/core-test.h
>> +++ b/mm/damon/core-test.h
>> @@ -266,6 +266,8 @@ static void damon_test_ops_registration(struct kunit *test)
>>  
>>  	/* Check double-registration failure again */
>>  	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), -EINVAL);
>> +
>> +	damon_destroy_ctx(c);
>>  }
>>  
>>  static void damon_test_set_regions(struct kunit *test)
>> @@ -342,6 +344,8 @@ static void damon_test_set_attrs(struct kunit *test)
>>  	invalid_attrs = valid_attrs;
>>  	invalid_attrs.aggr_interval = 4999;
>>  	KUNIT_EXPECT_EQ(test, damon_set_attrs(c, &invalid_attrs), -EINVAL);
>> +
>> +	damon_destroy_ctx(c);
>>  }
>>  
>>  static void damos_test_new_filter(struct kunit *test)
> 
> Other than above comments, changes look good to me.
> 
>> -- 
>> 2.34.1
>>
> 
> Thanks,
> SJ