On 17 Apr 2026, at 22:44, Zi Yan wrote: > Replace it with a check on the max folio order of the file's address space > mapping, making sure PMD THP is supported. Also remove the read-only fd > check, since collapse_file() now makes sure all to-be-collapsed folios are > clean and the created PMD file THP can be handled by FSes properly. > > Signed-off-by: Zi Yan <[email protected]> > --- > mm/huge_memory.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 970e077019b7..7e9cf8c0985f 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -86,9 +86,6 @@ 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; > > @@ -97,7 +94,10 @@ static inline bool file_thp_enabled(struct vm_area_struct > *vma) > if (IS_ANON_FILE(inode)) > return false; > > - return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
Hi Matthew, David, and Lorenzo, After some discussions on irc, I feel that we probably should not allow read-write fd for PMD THP collapse at the moment. Combining with the filemap_flush() under folio_dirty() check from collapse_file(), khugepaged would become a kwritebackd that scans pagecache folios and writes them back. If we limit it to read-only fds, at least khugepaged would only write back once for the pagecache folios from these fds. I am planning to restore inode_is_open_for_write() check in the next version. Let me know your thoughts. > + if (!mapping_pmd_thp_support(inode->i_mapping)) > + return false; > + > + return S_ISREG(inode->i_mode); > } > > /* If returns true, we are unable to access the VMA's folios. */ > -- > 2.43.0 -- Best Regards, Yan, Zi
