Merging upstream version 6.8.12.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 313f1c4276..aa8f5a6c32 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -213,6 +213,38 @@ out_release:
 	goto out;
 }
 
+static int mfill_atomic_pte_zeroed_folio(pmd_t *dst_pmd,
+					 struct vm_area_struct *dst_vma,
+					 unsigned long dst_addr)
+{
+	struct folio *folio;
+	int ret = -ENOMEM;
+
+	folio = vma_alloc_zeroed_movable_folio(dst_vma, dst_addr);
+	if (!folio)
+		return ret;
+
+	if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL))
+		goto out_put;
+
+	/*
+	 * The memory barrier inside __folio_mark_uptodate makes sure that
+	 * zeroing out the folio become visible before mapping the page
+	 * using set_pte_at(). See do_anonymous_page().
+	 */
+	__folio_mark_uptodate(folio);
+
+	ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
+				       &folio->page, true, 0);
+	if (ret)
+		goto out_put;
+
+	return 0;
+out_put:
+	folio_put(folio);
+	return ret;
+}
+
 static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
 				     struct vm_area_struct *dst_vma,
 				     unsigned long dst_addr)
@@ -221,6 +253,9 @@ static int mfill_atomic_pte_zeropage(pmd_t *dst_pmd,
 	spinlock_t *ptl;
 	int ret;
 
+	if (mm_forbids_zeropage(dst_vma->vm_mm))
+		return mfill_atomic_pte_zeroed_folio(dst_pmd, dst_vma, dst_addr);
+
 	_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
 					 dst_vma->vm_page_prot));
 	ret = -EAGAIN;