mm/huge_memory: remove READ_ONLY_THP_FOR_FS from file_thp_enabled()

Replace it with a check on the max folio order of the file's address space
mapping, making sure PMD folio is supported.  Keep the inode
open-for-write check, since even if collapse_file() now makes sure all
to-be-collapsed folios are clean and the created PMD file THP can be
handled by FSes properly, the filemap_flush() could perform undesirable
write back.

Link: https://lore.kernel.org/20260517135416.1434539-4-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Nico Pache <npache@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b4062396ce87742347df3f33796c9d140ac1477f..8808eb56ef0e3c8bf44547fe2d8306f4d955d399 100644 (file)
--- 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_pmd_folio_support(vma->vm_file->f_mapping))
+               return false;
+
        return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
 }