[LTP] [PATCH] syscalls/mallinfo01: Disable free fastbin blocks

[LTP] [PATCH] syscalls/mallinfo01: Disable free fastbin blocks

[Yang Xu]

When using malloc to allocate small space, it will use fastbin block firstly if
we have free fastbin free blocks, it is more quickly.
In here, we just test oldblks free chunks, it is the number of ordinary
(i.e. non-fastbin) free blocks. So use mallopt(M_MXFAST, 0) to disable
free fastbin block.

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 testcases/kernel/syscalls/mallinfo/mallinfo01.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/testcases/kernel/syscalls/mallinfo/mallinfo01.c b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
index 48fce0132..4e10e352e 100644
--- a/testcases/kernel/syscalls/mallinfo/mallinfo01.c
+++ b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
@@ -64,6 +64,8 @@ static void setup(void)
 {
 	if (sizeof(info1.arena) != sizeof(int))
 		tst_res(TFAIL, "The member of mallinfo struct is not int");
+	if (mallopt(M_MXFAST, 0) == 0)
+		tst_res(TFAIL, "mallopt(M_MXFAST, 0) failed");
 
 	info1 = mallinfo();
 	print_mallinfo("Start", &info1);
-- 
2.23.0

[LTP] [PATCH] syscalls/mallinfo01: Disable free fastbin blocks

[Martin Doucha]

Hello,

On 13. 05. 21 10:54, Yang Xu wrote:
> When using malloc to allocate small space, it will use fastbin block firstly if
> we have free fastbin free blocks, it is more quickly.
> In here, we just test oldblks free chunks, it is the number of ordinary
> (i.e. non-fastbin) free blocks. So use mallopt(M_MXFAST, 0) to disable
> free fastbin block.
> 
> Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
> ---
>  testcases/kernel/syscalls/mallinfo/mallinfo01.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/testcases/kernel/syscalls/mallinfo/mallinfo01.c b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
> index 48fce0132..4e10e352e 100644
> --- a/testcases/kernel/syscalls/mallinfo/mallinfo01.c
> +++ b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
> @@ -64,6 +64,8 @@ static void setup(void)
>  {
>  	if (sizeof(info1.arena) != sizeof(int))
>  		tst_res(TFAIL, "The member of mallinfo struct is not int");
> +	if (mallopt(M_MXFAST, 0) == 0)
> +		tst_res(TFAIL, "mallopt(M_MXFAST, 0) failed");
>  
>  	info1 = mallinfo();
>  	print_mallinfo("Start", &info1);
> 

Sorry but this does not fix the problem. The failing subtest assumes that:
- malloc() will never increase ordblks
- free() will allways increase ordblks

mallinfo01 is failing because both of these assumptions are wrong.
Disabling fastbin block usage will not fix the failure.

-- 
Martin Doucha   mdoucha@suse.cz
QA Engineer for Software Maintenance
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic

[LTP] [PATCH] syscalls/mallinfo01: Disable free fastbin blocks

[xuyang2018.jy]

Hi Martin
  I don't have a proper fix. So you can remove it from runtest file.

Best Regards
Yang Xu
> Hello,
>
> On 13. 05. 21 10:54, Yang Xu wrote:
>> When using malloc to allocate small space, it will use fastbin block firstly if
>> we have free fastbin free blocks, it is more quickly.
>> In here, we just test oldblks free chunks, it is the number of ordinary
>> (i.e. non-fastbin) free blocks. So use mallopt(M_MXFAST, 0) to disable
>> free fastbin block.
>>
>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>> ---
>>   testcases/kernel/syscalls/mallinfo/mallinfo01.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/testcases/kernel/syscalls/mallinfo/mallinfo01.c b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
>> index 48fce0132..4e10e352e 100644
>> --- a/testcases/kernel/syscalls/mallinfo/mallinfo01.c
>> +++ b/testcases/kernel/syscalls/mallinfo/mallinfo01.c
>> @@ -64,6 +64,8 @@ static void setup(void)
>>   {
>>   	if (sizeof(info1.arena) != sizeof(int))
>>   		tst_res(TFAIL, "The member of mallinfo struct is not int");
>> +	if (mallopt(M_MXFAST, 0) == 0)
>> +		tst_res(TFAIL, "mallopt(M_MXFAST, 0) failed");
>>
>>   	info1 = mallinfo();
>>   	print_mallinfo("Start",&info1);
>>
>
> Sorry but this does not fix the problem. The failing subtest assumes that:
> - malloc() will never increase ordblks
> - free() will allways increase ordblks
>
> mallinfo01 is failing because both of these assumptions are wrong.
> Disabling fastbin block usage will not fix the failure.
>

[LTP] [PATCH] syscalls/mallinfo01: Disable free fastbin blocks

[Cyril Hrubis]

Hi!
>   I don't have a proper fix. So you can remove it from runtest file.

I've pushed a patch that removes it from the runtest file, thanks.

-- 
Cyril Hrubis
chrubis@suse.cz