[PATCHv3, RFC 23/34] thp, mm: split huge page on mmap file page

[Kirill A. Shutemov]

From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

We are not ready to mmap file-backed tranparent huge pages. Let's split
them on fault attempt.

Later in the patchset we'll implement mmap() properly and this code path
be used for fallback cases.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 mm/filemap.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/filemap.c b/mm/filemap.c
index 3296f5c..6f0e3be 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1683,6 +1683,8 @@ retry_find:
 			goto no_cached_page;
 	}
 
+	if (PageTransCompound(page))
+		split_huge_page(compound_trans_head(page));
 	if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
 		page_cache_release(page);
 		return ret | VM_FAULT_RETRY;
-- 
1.7.10.4

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