On 27 Mar 2026, at 8:42, Lorenzo Stoakes (Oracle) wrote: > On Thu, Mar 26, 2026 at 09:42:50PM -0400, Zi Yan wrote: >> Replace it with a check on the max folio order of the file's address space >> mapping, making sure PMD_ORDER is supported. >> >> Signed-off-by: Zi Yan <[email protected]> >> --- >> mm/huge_memory.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index c7873dbdc470..1da1467328a3 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -89,9 +89,6 @@ static inline bool file_thp_enabled(struct vm_area_struct >> *vma) >> { >> struct inode *inode; >> >> - if (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) >> - return false; >> - >> if (!vma->vm_file) >> return false; >> >> @@ -100,6 +97,9 @@ static inline bool file_thp_enabled(struct vm_area_struct >> *vma) >> if (IS_ANON_FILE(inode)) >> return false; >> >> + if (mapping_max_folio_order(inode->i_mapping) < PMD_ORDER) >> + return false; >> + > > At this point I think this should be a separate function quite honestly and > share it with 2/10's use, and then you can put the comment in here re: anon > shmem etc. > > Though that won't apply here of course as shmem_allowable_huge_orders() would > have been invoked :) > > But no harm in refactoring it anyway, and the repetitive < PMD_ORDER stuff is > unfortunate. > > Buuut having said that is this right actually? > > Because we have: > > if (((in_pf || smaps)) && vma->vm_ops->huge_fault) > return orders; > > Above it, and now you're enabling huge folio file systems to do non-page fault > THP and that's err... isn't that quite a big change?
That is what READ_ONLY_THP_FOR_FS does, creating THPs after page faults, right? This patchset changes the condition from all FSes to FSes with large folio support. Will add a helper, mapping_support_pmd_folio(), for mapping_max_folio_order(inode->i_mapping) < PMD_ORDER. > > So yeah probably no to this patch as is :) we should just drop > file_thp_enabled()? > >> return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); >> } >> >> -- >> 2.43.0 >> Best Regards, Yan, Zi
