Re: [PATCH v2 1/2] mm: huge_memory: disallow hugepages if the system-wide THP sysfs settings are disabled

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2025/6/7 02:47, Dev Jain wrote:
> 
> On 06/06/25 10:19 pm, Dev Jain wrote:
>>
>> On 05/06/25 1:30 pm, Baolin Wang wrote:
>>> The MADV_COLLAPSE will ignore the system-wide Anon THP sysfs 
>>> settings, which
>>> means that even though we have disabled the Anon THP configuration, 
>>> MADV_COLLAPSE
>>> will still attempt to collapse into a Anon THP. This violates the 
>>> rule we have
>>> agreed upon: never means never.
>>>
>>> Another rule for madvise, referring to David's suggestion: “allowing 
>>> for collapsing
>>> in a VM without VM_HUGEPAGE in the "madvise" mode would be fine".
>>>
>>> To address this issue, should check whether the Anon THP 
>>> configuration is disabled
>>> in thp_vma_allowable_orders(), even when the TVA_ENFORCE_SYSFS flag 
>>> is set.
>>
>> Did you mean to say "even when the TVA_ENFORCE_SYSFS flag is *not* 
>> set"? Because if
>> is set, then we have to check the anon THP sysfs config.

Sorry for the confusion. What I mean is that we should also check 
whether the Anon THP is disabled when the TVA_ENFORCE_SYSFS flag is set. 
Will update the commit message.

> Otherwise the patch itself looks good to me, so:
> 
> Reviewed-by: Dev Jain <dev.jain@arm.com>

Thanks for reviewing.