Linux 2.6.35.3

3 files changed, 40 insertions, 6 deletions

diff --git a/mm/memory.c b/mm/memory.c
index bde42c6d3633..307bf77fc441 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2760,6 +2760,26 @@ out_release:
 }
 
 /*
+ * This is like a special single-page "expand_downwards()",
+ * except we must first make sure that 'address-PAGE_SIZE'
+ * doesn't hit another vma.
+ *
+ * The "find_vma()" will do the right thing even if we wrap
+ */
+static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
+{
+	address &= PAGE_MASK;
+	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
+		address -= PAGE_SIZE;
+		if (find_vma(vma->vm_mm, address) != vma)
+			return -ENOMEM;
+
+		expand_stack(vma, address);
+	}
+	return 0;
+}
+
+/*
  * We enter with non-exclusive mmap_sem (to exclude vma changes,
  * but allow concurrent faults), and pte mapped but not yet locked.
  * We return with mmap_sem still held, but pte unmapped and unlocked.
@@ -2772,19 +2792,23 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	spinlock_t *ptl;
 	pte_t entry;
 
+	pte_unmap(page_table);
+
+	/* Check if we need to add a guard page to the stack */
+	if (check_stack_guard_page(vma, address) < 0)
+		return VM_FAULT_SIGBUS;
+
+	/* Use the zero-page for reads */
 	if (!(flags & FAULT_FLAG_WRITE)) {
 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
 						vma->vm_page_prot));
-		ptl = pte_lockptr(mm, pmd);
-		spin_lock(ptl);
+		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 		if (!pte_none(*page_table))
 			goto unlock;
 		goto setpte;
 	}
 
 	/* Allocate our own private page. */
-	pte_unmap(page_table);
-
 	if (unlikely(anon_vma_prepare(vma)))
 		goto oom;
 	page = alloc_zeroed_user_highpage_movable(vma, address);
diff --git a/mm/mlock.c b/mm/mlock.c
index 3f82720e0515..49e5e4cb8232 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -167,6 +167,14 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
 	if (vma->vm_flags & VM_WRITE)
 		gup_flags |= FOLL_WRITE;
 
+	/* We don't try to access the guard page of a stack vma */
+	if (vma->vm_flags & VM_GROWSDOWN) {
+		if (start == vma->vm_start) {
+			start += PAGE_SIZE;
+			nr_pages--;
+		}
+	}
+
 	while (nr_pages > 0) {
 		int i;
 
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 03aa2d55f1a2..f08d165871b3 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -318,8 +318,10 @@ checks:
 	if (offset > si->highest_bit)
 		scan_base = offset = si->lowest_bit;
 
-	/* reuse swap entry of cache-only swap if not busy. */
-	if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+	/* reuse swap entry of cache-only swap if not hibernation. */
+	if (vm_swap_full()
+		&& usage == SWAP_HAS_CACHE
+		&& si->swap_map[offset] == SWAP_HAS_CACHE) {
 		int swap_was_freed;
 		spin_unlock(&swap_lock);
 		swap_was_freed = __try_to_reclaim_swap(si, offset);