Merge branch 'akpm' (patches from Andrew)

Merge fixes from Andrew Morton:
 "26 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (26 commits)
  userfaultfd: remove wrong comment from userfaultfd_ctx_get()
  fat: fix using uninitialized fields of fat_inode/fsinfo_inode
  sh: cayman: IDE support fix
  kasan: fix races in quarantine_remove_cache()
  kasan: resched in quarantine_remove_cache()
  mm: do not call mem_cgroup_free() from within mem_cgroup_alloc()
  thp: fix another corner case of munlock() vs. THPs
  rmap: fix NULL-pointer dereference on THP munlocking
  mm/memblock.c: fix memblock_next_valid_pfn()
  userfaultfd: selftest: vm: allow to build in vm/ directory
  userfaultfd: non-cooperative: userfaultfd_remove revalidate vma in MADV_DONTNEED
  userfaultfd: non-cooperative: fix fork fctx->new memleak
  mm/cgroup: avoid panic when init with low memory
  drivers/md/bcache/util.h: remove duplicate inclusion of blkdev.h
  mm/vmstats: add thp_split_pud event for clarity
  include/linux/fs.h: fix unsigned enum warning with gcc-4.2
  userfaultfd: non-cooperative: release all ctx in dup_userfaultfd_complete
  userfaultfd: non-cooperative: robustness check
  userfaultfd: non-cooperative: rollback userfaultfd_exit
  x86, mm: unify exit paths in gup_pte_range()
  ...

2 files changed, 33 insertions, 49 deletions

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 338d2f73eb29c..a2c05f2ada6dd 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1359,6 +1359,16 @@ out:
 	return 0;
 }
 
+static void fat_dummy_inode_init(struct inode *inode)
+{
+	/* Initialize this dummy inode to work as no-op. */
+	MSDOS_I(inode)->mmu_private = 0;
+	MSDOS_I(inode)->i_start = 0;
+	MSDOS_I(inode)->i_logstart = 0;
+	MSDOS_I(inode)->i_attrs = 0;
+	MSDOS_I(inode)->i_pos = 0;
+}
+
 static int fat_read_root(struct inode *inode)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
@@ -1803,12 +1813,13 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	fat_inode = new_inode(sb);
 	if (!fat_inode)
 		goto out_fail;
-	MSDOS_I(fat_inode)->i_pos = 0;
+	fat_dummy_inode_init(fat_inode);
 	sbi->fat_inode = fat_inode;
 
 	fsinfo_inode = new_inode(sb);
 	if (!fsinfo_inode)
 		goto out_fail;
+	fat_dummy_inode_init(fsinfo_inode);
 	fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
 	sbi->fsinfo_inode = fsinfo_inode;
 	insert_inode_hash(fsinfo_inode);
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 973607df579db..2bb1c72380f29 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -138,8 +138,6 @@ out:
  * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd
  * context.
  * @ctx: [in] Pointer to the userfaultfd context.
- *
- * Returns: In case of success, returns not zero.
  */
 static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx)
 {
@@ -490,7 +488,7 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason)
 			 * in such case.
 			 */
 			down_read(&mm->mmap_sem);
-			ret = 0;
+			ret = VM_FAULT_NOPAGE;
 		}
 	}
 
@@ -527,10 +525,11 @@ out:
 	return ret;
 }
 
-static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
-					     struct userfaultfd_wait_queue *ewq)
+static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
+					      struct userfaultfd_wait_queue *ewq)
 {
-	int ret = 0;
+	if (WARN_ON_ONCE(current->flags & PF_EXITING))
+		goto out;
 
 	ewq->ctx = ctx;
 	init_waitqueue_entry(&ewq->wq, current);
@@ -547,8 +546,16 @@ static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
 			break;
 		if (ACCESS_ONCE(ctx->released) ||
 		    fatal_signal_pending(current)) {
-			ret = -1;
 			__remove_wait_queue(&ctx->event_wqh, &ewq->wq);
+			if (ewq->msg.event == UFFD_EVENT_FORK) {
+				struct userfaultfd_ctx *new;
+
+				new = (struct userfaultfd_ctx *)
+					(unsigned long)
+					ewq->msg.arg.reserved.reserved1;
+
+				userfaultfd_ctx_put(new);
+			}
 			break;
 		}
 
@@ -566,9 +573,8 @@ static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
 	 * ctx may go away after this if the userfault pseudo fd is
 	 * already released.
 	 */
-
+out:
 	userfaultfd_ctx_put(ctx);
-	return ret;
 }
 
 static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx,
@@ -626,7 +632,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
 	return 0;
 }
 
-static int dup_fctx(struct userfaultfd_fork_ctx *fctx)
+static void dup_fctx(struct userfaultfd_fork_ctx *fctx)
 {
 	struct userfaultfd_ctx *ctx = fctx->orig;
 	struct userfaultfd_wait_queue ewq;
@@ -636,17 +642,15 @@ static int dup_fctx(struct userfaultfd_fork_ctx *fctx)
 	ewq.msg.event = UFFD_EVENT_FORK;
 	ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new;
 
-	return userfaultfd_event_wait_completion(ctx, &ewq);
+	userfaultfd_event_wait_completion(ctx, &ewq);
 }
 
 void dup_userfaultfd_complete(struct list_head *fcs)
 {
-	int ret = 0;
 	struct userfaultfd_fork_ctx *fctx, *n;
 
 	list_for_each_entry_safe(fctx, n, fcs, list) {
-		if (!ret)
-			ret = dup_fctx(fctx);
+		dup_fctx(fctx);
 		list_del(&fctx->list);
 		kfree(fctx);
 	}
@@ -689,8 +693,7 @@ void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx,
 	userfaultfd_event_wait_completion(ctx, &ewq);
 }
 
-void userfaultfd_remove(struct vm_area_struct *vma,
-			struct vm_area_struct **prev,
+bool userfaultfd_remove(struct vm_area_struct *vma,
 			unsigned long start, unsigned long end)
 {
 	struct mm_struct *mm = vma->vm_mm;
@@ -699,13 +702,11 @@ void userfaultfd_remove(struct vm_area_struct *vma,
 
 	ctx = vma->vm_userfaultfd_ctx.ctx;
 	if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE))
-		return;
+		return true;
 
 	userfaultfd_ctx_get(ctx);
 	up_read(&mm->mmap_sem);
 
-	*prev = NULL; /* We wait for ACK w/o the mmap semaphore */
-
 	msg_init(&ewq.msg);
 
 	ewq.msg.event = UFFD_EVENT_REMOVE;
@@ -714,7 +715,7 @@ void userfaultfd_remove(struct vm_area_struct *vma,
 
 	userfaultfd_event_wait_completion(ctx, &ewq);
 
-	down_read(&mm->mmap_sem);
+	return false;
 }
 
 static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps,
@@ -775,34 +776,6 @@ void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
 	}
 }
 
-void userfaultfd_exit(struct mm_struct *mm)
-{
-	struct vm_area_struct *vma = mm->mmap;
-
-	/*
-	 * We can do the vma walk without locking because the caller
-	 * (exit_mm) knows it now has exclusive access
-	 */
-	while (vma) {
-		struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
-
-		if (ctx && (ctx->features & UFFD_FEATURE_EVENT_EXIT)) {
-			struct userfaultfd_wait_queue ewq;
-
-			userfaultfd_ctx_get(ctx);
-
-			msg_init(&ewq.msg);
-			ewq.msg.event = UFFD_EVENT_EXIT;
-
-			userfaultfd_event_wait_completion(ctx, &ewq);
-
-			ctx->features &= ~UFFD_FEATURE_EVENT_EXIT;
-		}
-
-		vma = vma->vm_next;
-	}
-}
-
 static int userfaultfd_release(struct inode *inode, struct file *file)
 {
 	struct userfaultfd_ctx *ctx = file->private_data;