The loser of a race to service a pte for a device private entry in the
swap path previously unlocked the ptl, but failed to unmap the pte. This
only affects highmem systems since unmapping a pte is a noop on
non-highmem systems.
Fixes: 16ce101db85d ("mm/memory.c: fix race when faulting a device private page")
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
---
mm/memory.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index f69fbc251198..ed429e20a1bb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3728,10 +3728,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
vmf->page = pfn_swap_entry_to_page(entry);
vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
vmf->address, &vmf->ptl);
- if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
- spin_unlock(vmf->ptl);
- goto out;
- }
+ if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
+ goto unlock;
/*
* Get a page reference while we know the page can't be
--
2.25.1
