[PATCH] elf: Fix elf/tst-decorate-maps on aarch64 after 321e1fc73f

[Dev Jain]

On 18/12/25 5:56 pm, Adhemerval Zanella Netto wrote:
>
> On 18/12/25 03:27, Dev Jain wrote:
>> On 18/12/25 2:25 am, Adhemerval Zanella wrote:
>>> The malloc size might be too low to trigger the mmap call on aarch64
>>> with mTHP.
>> Thanks, but mTHP has got nothing to do with mmap() getting triggered by
>> malloc() - it is dependent on MMAP_THRESHOLD? I think we can have this
>> change when we get around changing the hardcoded tunables according
>> to whether THP is there by default or not - we definitely should
>> increase MMAP_THRESHOLD in that case.
> The test is issued with
>
> tst-decorate-maps-ENV = \
>   GLIBC_TUNABLES=glibc.malloc.arena_max=8:glibc.malloc.mmap_threshold=1024:glibc.mem.decorate_maps=1
> tst-decorate-maps-ARGS = 8

So currently we do xmalloc (256 * 1024), which is greater than glibc.malloc.mmap_threshold=1024,
so mmap gets triggered right? If you are trying to say that this size is not enough to back the returned
memory with a 2MB THP - why is it necessary for this test?

>
>>> Checked on aarch64-linux-gnu.
>>> ---
>>>  elf/tst-decorate-maps.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/elf/tst-decorate-maps.c b/elf/tst-decorate-maps.c
>>> index 715fdf5209..c20d059503 100644
>>> --- a/elf/tst-decorate-maps.c
>>> +++ b/elf/tst-decorate-maps.c
>>> @@ -109,7 +109,7 @@ do_test_threads (bool set_guard)
>>>    xpthread_barrier_init (&b, NULL, num_threads + 1);
>>>  
>>>    /* Issue a large malloc to trigger a mmap call.  */
>>> -  void *p = xmalloc (256 * 1024);
>>> +  void *p = xmalloc (2 * 1024 * 1024);
>>>  
>>>    pthread_t thr[num_threads];
>>>    {