1 files changed, 21 insertions, 5 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 388dcf9..bb04d8f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -61,6 +61,7 @@
 #include <linux/string.h>
 #include <linux/dma-debug.h>
 #include <linux/debugfs.h>
+#include <linux/userfaultfd_k.h>
 
 #include <asm/io.h>
 #include <asm/pgalloc.h>
@@ -180,22 +181,22 @@ static void check_sync_rss_stat(struct task_struct *task)
 
 #ifdef HAVE_GENERIC_MMU_GATHER
 
-static int tlb_next_batch(struct mmu_gather *tlb)
+static bool tlb_next_batch(struct mmu_gather *tlb)
 {
 	struct mmu_gather_batch *batch;
 
 	batch = tlb->active;
 	if (batch->next) {
 		tlb->active = batch->next;
-		return 1;
+		return true;
 	}
 
 	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
-		return 0;
+		return false;
 
 	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 	if (!batch)
-		return 0;
+		return false;
 
 	tlb->batch_count++;
 	batch->next = NULL;
@@ -205,7 +206,7 @@ static int tlb_next_batch(struct mmu_gather *tlb)
 	tlb->active->next = batch;
 	tlb->active = batch;
 
-	return 1;
+	return true;
 }
 
 /* tlb_gather_mmu
@@ -2685,6 +2686,12 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 		if (!pte_none(*page_table))
 			goto unlock;
+		/* Deliver the page fault to userland, check inside PT lock */
+		if (userfaultfd_missing(vma)) {
+			pte_unmap_unlock(page_table, ptl);
+			return handle_userfault(vma, address, flags,
+						VM_UFFD_MISSING);
+		}
 		goto setpte;
 	}
 
@@ -2713,6 +2720,15 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (!pte_none(*page_table))
 		goto release;
 
+	/* Deliver the page fault to userland, check inside PT lock */
+	if (userfaultfd_missing(vma)) {
+		pte_unmap_unlock(page_table, ptl);
+		mem_cgroup_cancel_charge(page, memcg);
+		page_cache_release(page);
+		return handle_userfault(vma, address, flags,
+					VM_UFFD_MISSING);
+	}
+
 	inc_mm_counter_fast(mm, MM_ANONPAGES);
 	page_add_new_anon_rmap(page, vma, address);
 	mem_cgroup_commit_charge(page, memcg, false);