On 23 Mar 2026, at 15:41, David Hildenbrand (Arm) wrote: > On 3/23/26 20:06, Zi Yan wrote: >> READ_ONLY_THP_FOR_FS is no longer present, remove corresponding code. >> >> Signed-off-by: Zi Yan <[email protected]> >> --- >> mm/khugepaged.c | 159 +++++++++++------------------------------------- >> 1 file changed, 34 insertions(+), 125 deletions(-) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index b2ac28ddd480..39f0b8959535 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -1899,7 +1899,7 @@ static enum scan_result collapse_file(struct mm_struct >> *mm, unsigned long addr, >> int nr_none = 0; >> bool is_shmem = shmem_file(file); >> >> - VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); >> + VM_WARN_ON_ONCE(!is_shmem); > > Oh, but if that means that khugepaged cannot collapse large folios in > FSes anymore, then this is the wrong approach I suppose? > > I would have assumed that we would now collapse for any files that > support large folios (in PMD size), not stopping to collapse entirely.
My understanding is that collapse_file() is only used for READ_ONLY_THP_FOR_FS. If FSes with large folio support also use it, I can replace IS_ENABLE with mapping_large_folio_support(). Best Regards, Yan, Zi
