Re: [PATCH 7.2 v2 01/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check

David Hildenbrand (Arm)
2026-04-14T10:19:16Z

On 4/13/26 22:34, Zi Yan wrote:
> On 13 Apr 2026, at 16:20, Matthew Wilcox wrote:
>
>> On Mon, Apr 13, 2026 at 03:20:19PM -0400, Zi Yan wrote:
>>> collapse_file() requires FSes supporting large folio with at least
>>> PMD_ORDER, so replace the READ_ONLY_THP_FOR_FS check with that.
>>> MADV_COLLAPSE ignores shmem huge config, so exclude the check for shmem.
>>>
>>> While at it, replace VM_BUG_ON with VM_WARN_ON_ONCE.
>>
>> Why? These are bugs. I don't think we gain anything from continuing.
>
> The goal is to catch these issues during development. VM_BUG_ON crashes
> the system and that is too much for such issues in collapse_file().

VM_BUG_ON should have never been added to the kernel.

--
Cheers,

David