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Diffstat (limited to 'mm')
-rw-r--r--mm/huge_memory.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 89932fd0f62e..db7946a0a28c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3009,30 +3009,36 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
if (new_order >= folio_order(folio))
return -EINVAL;
- /* Cannot split anonymous THP to order-1 */
- if (new_order == 1 && folio_test_anon(folio)) {
- VM_WARN_ONCE(1, "Cannot split to order-1 folio");
- return -EINVAL;
- }
-
- if (new_order) {
- /* Only swapping a whole PMD-mapped folio is supported */
- if (folio_test_swapcache(folio))
+ if (folio_test_anon(folio)) {
+ /* order-1 is not supported for anonymous THP. */
+ if (new_order == 1) {
+ VM_WARN_ONCE(1, "Cannot split to order-1 folio");
return -EINVAL;
+ }
+ } else if (new_order) {
/* Split shmem folio to non-zero order not supported */
if (shmem_mapping(folio->mapping)) {
VM_WARN_ONCE(1,
"Cannot split shmem folio to non-0 order");
return -EINVAL;
}
- /* No split if the file system does not support large folio */
- if (!mapping_large_folio_support(folio->mapping)) {
+ /*
+ * No split if the file system does not support large folio.
+ * Note that we might still have THPs in such mappings due to
+ * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping
+ * does not actually support large folios properly.
+ */
+ if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
+ !mapping_large_folio_support(folio->mapping)) {
VM_WARN_ONCE(1,
"Cannot split file folio to non-0 order");
return -EINVAL;
}
}
+ /* Only swapping a whole PMD-mapped folio is supported */
+ if (folio_test_swapcache(folio) && new_order)
+ return -EINVAL;
is_hzp = is_huge_zero_folio(folio);
if (is_hzp) {