[PATCH v6 37/51] mm: Remove page fault assumption of compound page size

[Matthew Wilcox]

From: "Matthew Wilcox (Oracle)" <wi...@infradead.org>

A compound page in the page cache will not necessarily be of PMD size,
so check explicitly.

Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
---
 mm/memory.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index dc7f3543b1fd..3e6ef0ebfdd0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3552,13 +3552,14 @@ static vm_fault_t do_set_pmd(struct vm_fault *vmf, 
struct page *page)
        unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
        pmd_t entry;
        int i;
-       vm_fault_t ret;
+       vm_fault_t ret = VM_FAULT_FALLBACK;
 
        if (!transhuge_vma_suitable(vma, haddr))
-               return VM_FAULT_FALLBACK;
+               return ret;
 
-       ret = VM_FAULT_FALLBACK;
        page = compound_head(page);
+       if (page_order(page) != HPAGE_PMD_ORDER)
+               return ret;
 
        /*
         * Archs like ppc64 need additonal space to store information
-- 
2.26.2