[PATCH v4 24/36] mm: Remove page fault assumption of compound page size

Matthew Wilcox
2020-05-15T13:18:13Z

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

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

diff --git a/mm/memory.c b/mm/memory.c
index f703fe8c8346..d68ce428ddd2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3549,13 +3549,14 @@ 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