From: Andrew Morton <akpm@linux-foundation.org>
Date: Tue, 8 Sep 2015 21:58:43 +0000 (-0700)
Subject: dax: revert userfaultfd change
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7c414164593514f76b422faae0824bdd3754209b;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

dax: revert userfaultfd change

Undo the change which "userfaultfd: call handle_userfault() for
userfaultfd_missing() faults" made to set_huge_zero_page().  DAX will
need that return value.

Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4d5fcb630d32..ca475dfdb28f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -794,16 +794,19 @@ static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
 }
 
 /* Caller must hold page table lock. */
-static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
+static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 		struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
 		struct page *zero_page)
 {
 	pmd_t entry;
+	if (!pmd_none(*pmd))
+		return false;
 	entry = mk_pmd(zero_page, vma->vm_page_prot);
 	entry = pmd_mkhuge(entry);
 	pgtable_trans_huge_deposit(mm, pmd, pgtable);
 	set_pmd_at(mm, haddr, pmd, entry);
 	atomic_long_inc(&mm->nr_ptes);
+	return true;
 }
 
 int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,