linux-kernel - Re: [PATCH] selftests/mm: Fixed incorrect buffer->mirror size in hmm2 double

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Message-ID: <831bb979-e27f-4af0-b933-5b05895aff8f@linux.ibm.com>
Date: Fri, 27 Sep 2024 16:21:30 +0530
From: Donet Tom <donettom@...ux.ibm.com>
To: Muhammad Usama Anjum <Usama.Anjum@...labora.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>,
        Jérôme Glisse <jglisse@...hat.com>
Cc: linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ritesh Harjani <ritesh.list@...il.com>,
        Kees Cook <keescook@...omium.org>, Mark Brown <broonie@...nel.org>,
        Przemek Kitszel <przemyslaw.kitszel@...el.com>
Subject: Re: [PATCH] selftests/mm: Fixed incorrect buffer->mirror size in hmm2
 double_map test


On 9/27/24 12:48, Muhammad Usama Anjum wrote:
> On 9/27/24 10:07 AM, Donet Tom wrote:
>> The hmm2 double_map test was failing due to an incorrect
>> buffer->mirror size. The buffer->mirror size was 6, while buffer->ptr
>> size was 6 * PAGE_SIZE. The test failed because the kernel's
>> copy_to_user function was attempting to copy a 6 * PAGE_SIZE buffer
>> to buffer->mirror. Since the size of buffer->mirror was incorrect,
>> copy_to_user failed.
>>
>> This patch corrects the buffer->mirror size to 6 * PAGE_SIZE.
>>
>> Test Result without this patch
>> ==============================
>>   #  RUN           hmm2.hmm2_device_private.double_map ...
>>   # hmm-tests.c:1680:double_map:Expected ret (-14) == 0 (0)
>>   # double_map: Test terminated by assertion
>>   #          FAIL  hmm2.hmm2_device_private.double_map
>>   not ok 53 hmm2.hmm2_device_private.double_map
>>
>> Test Result with this patch
>> ===========================
>>   #  RUN           hmm2.hmm2_device_private.double_map ...
>>   #            OK  hmm2.hmm2_device_private.double_map
>>   ok 53 hmm2.hmm2_device_private.double_map
>>
>> Signed-off-by: Donet Tom <donettom@...ux.ibm.com>
> Please add Fixes-by tag. Other than this, LGTM

Fixes-by : Donet Tom <donettom@...ux.ibm.com>

I have added the Fixes-by tag here. Please let me know if you would prefer that I send a V2 with this tag.

>
> Reviewed-by: Muhammad Usama Anjum <usama.anjum@...labora.com>

Thank you
Donet

>
>> ---
>>   tools/testing/selftests/mm/hmm-tests.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
>> index d2cfc9b494a0..141bf63cbe05 100644
>> --- a/tools/testing/selftests/mm/hmm-tests.c
>> +++ b/tools/testing/selftests/mm/hmm-tests.c
>> @@ -1657,7 +1657,7 @@ TEST_F(hmm2, double_map)
>>   
>>   	buffer->fd = -1;
>>   	buffer->size = size;
>> -	buffer->mirror = malloc(npages);
>> +	buffer->mirror = malloc(size);
>>   	ASSERT_NE(buffer->mirror, NULL);
>>   
>>   	/* Reserve a range of addresses. */