Merge branch 'akpm' (patches from Andrew)

Mergr misc fixes from Andrew Morton:
 "11 fixes"

Mostly VM fixes, one psi polling fix, and one parisc build fix.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm/kasan: fix false positive invalid-free reports with CONFIG_KASAN_SW_TAGS=y
  mm/zsmalloc.c: fix race condition in zs_destroy_pool
  mm/zsmalloc.c: migration can leave pages in ZS_EMPTY indefinitely
  mm, page_owner: handle THP splits correctly
  userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx
  psi: get poll_work to run when calling poll syscall next time
  mm: memcontrol: flush percpu vmevents before releasing memcg
  mm: memcontrol: flush percpu vmstats before releasing memcg
  parisc: fix compilation errrors
  mm, page_alloc: move_freepages should not examine struct page of reserved memory
  mm/z3fold.c: fix race between migration and destruction

1 files changed, 13 insertions, 12 deletions

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index ccbdbd62f0d8..fe6d804a38dc 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -880,6 +880,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 	/* len == 0 means wake all */
 	struct userfaultfd_wake_range range = { .len = 0, };
 	unsigned long new_flags;
+	bool still_valid;
 
 	WRITE_ONCE(ctx->released, true);
 
@@ -895,8 +896,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 	 * taking the mmap_sem for writing.
 	 */
 	down_write(&mm->mmap_sem);
-	if (!mmget_still_valid(mm))
-		goto skip_mm;
+	still_valid = mmget_still_valid(mm);
 	prev = NULL;
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 		cond_resched();
@@ -907,19 +907,20 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 			continue;
 		}
 		new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP);
-		prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
-				 new_flags, vma->anon_vma,
-				 vma->vm_file, vma->vm_pgoff,
-				 vma_policy(vma),
-				 NULL_VM_UFFD_CTX);
-		if (prev)
-			vma = prev;
-		else
-			prev = vma;
+		if (still_valid) {
+			prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end,
+					 new_flags, vma->anon_vma,
+					 vma->vm_file, vma->vm_pgoff,
+					 vma_policy(vma),
+					 NULL_VM_UFFD_CTX);
+			if (prev)
+				vma = prev;
+			else
+				prev = vma;
+		}
 		vma->vm_flags = new_flags;
 		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
 	}
-skip_mm:
 	up_write(&mm->mmap_sem);
 	mmput(mm);
 wakeup: