[PATCH 1/2] ntdll/tests: Check that creating huge thread stacks should work.

[Rémi Bernon]

On 5/7/21 1:56 PM, Gabriel Ivăncescu wrote:
> On 07/05/2021 14:44, Rémi Bernon wrote:
>> On 5/7/21 1:38 PM, Gabriel Ivăncescu wrote:
>>> On 07/05/2021 13:20, Rémi Bernon wrote:
>>>> On 5/7/21 12:08 PM, Rémi Bernon wrote:
>>>>> Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
>>>>> ---
>>>>>
>>>>> I'm not completely sure what 789c1db18a4e192425da3771cac4726cda77130b
>>>>> was for, but it seems to be causing spurious failures. This fix is
>>>>> trying to keep the current behavior, but it may be better to 
>>>>> completely
>>>>> revert the commit as, although less likely, TEB allocation could also
>>>>> fail much more often.
>>>>>
>>>>>   dlls/ntdll/tests/virtual.c | 10 ++++++++++
>>>>>   1 file changed, 10 insertions(+)
>>>>>
>>>>> diff --git a/dlls/ntdll/tests/virtual.c b/dlls/ntdll/tests/virtual.c
>>>>> index 8f5b0092bea..686b4076801 100644
>>>>> --- a/dlls/ntdll/tests/virtual.c
>>>>> +++ b/dlls/ntdll/tests/virtual.c
>>>>> @@ -488,6 +488,11 @@ static DWORD WINAPI 
>>>>> test_stack_size_thread(void *ptr)
>>>>>       return 0;
>>>>>   }
>>>>> +static DWORD WINAPI test_stack_size_dummy_thread(void *ptr)
>>>>> +{
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>>   static void test_RtlCreateUserStack(void)
>>>>>   {
>>>>>       IMAGE_NT_HEADERS *nt = RtlImageNtHeader( 
>>>>> NtCurrentTeb()->Peb->ImageBaseAddress );
>>>>> @@ -563,6 +568,11 @@ static void test_RtlCreateUserStack(void)
>>>>>       thread = CreateThread(NULL, 0x3ff000, test_stack_size_thread, 
>>>>> &args, STACK_SIZE_PARAM_IS_A_RESERVATION, NULL);
>>>>>       WaitForSingleObject(thread, INFINITE);
>>>>>       CloseHandle(thread);
>>>>> +
>>>>> +    thread = CreateThread(NULL, 0x80000000, 
>>>>> test_stack_size_dummy_thread, NULL, 
>>>>> STACK_SIZE_PARAM_IS_A_RESERVATION, NULL);
>>>>> +    todo_wine ok(thread != NULL, "CreateThread with huge stack 
>>>>> failed\n");
>>>>> +    WaitForSingleObject(thread, INFINITE);
>>>>> +    CloseHandle(thread);
>>>>>   }
>>>>>   static void test_NtMapViewOfSection(void)
>>>>>
>>>>
>>>> Eh obviously that fails on 32bit. Anyway, I'm not sure at all about 
>>>> the fix, it's maybe something related to allocations that should be 
>>>> bottom-up by default?
>>>
>>> There's a wine-staging patch that does this and fixes some bugs:
>>>
>>> ntdll-ForceBottomUpAlloc
>>>
>>> Does it help? Also what happens on Windows if you force top-down 
>>> allocation?
>>
>> It doesn't help with the regression, because we now forcefully limit 
>> the address space where the thread stack / teb can be allocated.
>>
>> What I meant was that although I don't know why it's been added, and 
>> if the reason was to make sure early threads are allocated on low 
>> addresses, maybe making default allocation strategy bottom-up is the 
>> correct fix (instead of trying to forcefully put them in the low 2G).
>>
>> I think that patch set has been sent already before but it was 
>> considered a bit over complicated.
> 
> Yeah, but if all allocations are forced bottom-up, not just the thread 
> stack/TEB, then the staging patch should already fix this, implicitly.
> 

I think it makes things ever worse as more things will be allocated in 
the low address space?

> An interesting thing is if you forced top-down allocation on Windows, do 
> they get allocated in low 2G? Info here:
> 
> https://tedwvc.wordpress.com/2013/07/16/porting-win32-code-to-64-bit-watch-out-for-pointers/ 
> 
> 
> I think that would explain Windows behavior and whether it special cases 
> them or not.

I don't understand, you can't control thread stack allocation strategy. 
At least not using CreateThread.
-- 
Rémi Bernon <rbernon at codeweavers.com>