[PATCH] mm: do not call do_fault_around for non-linear fault

[Konstantin Khlebnikov]

From: Konstantin Khlebnikov <koct9i@xxxxxxxxx>

Faulting around non-linear page-fault has no sense and
breaks logic in do_fault_around because pgoff is shifted.

Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Reported-by: "Ingo Korb" <ingo.korb@xxxxxxxxxxxxxx>
---
 mm/memory.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index d67fd9f..7e8d820 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2882,7 +2882,8 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * if page by the offset is not ready to be mapped (cold cache or
 	 * something).
 	 */
-	if (vma->vm_ops->map_pages && fault_around_pages() > 1) {
+	if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
+	    fault_around_pages() > 1) {
 		pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 		do_fault_around(vma, address, pte, pgoff, flags);
 		if (!pte_same(*pte, orig_pte))

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