On 2026/3/27 15:29, Lance Yang wrote:
On Thu, Mar 26, 2026 at 09:42:47PM -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. shmem with
huge option turned on also sets large folio order on mapping, so the check
also applies to shmem.
While at it, replace VM_BUG_ON with returning failure values.
Signed-off-by: Zi Yan <[email protected]>
---
mm/khugepaged.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d06d84219e1b..45b12ffb1550 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1899,8 +1899,11 @@ 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_BUG_ON(start & (HPAGE_PMD_NR - 1));
+ /* "huge" shmem sets mapping folio order and passes the check below */
+ if (mapping_max_folio_order(mapping) < PMD_ORDER)
+ return SCAN_FAIL;
Yep, for shmem inodes, if the mount has huge= enabled, inode creation
marks the mapping are large-folio capable:
Oops, s/are/as/
/* Don't consider 'deny' for emergencies and 'force' for testing */
if (sbinfo->huge)
mapping_set_large_folios(inode->i_mapping);
LGTM!
Reviewed-by: Lance Yang <[email protected]>
