Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "31 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (31 commits)
  ocfs2: fix potential use after free
  mm/khugepaged: fix the xas_create_range() error path
  mm/khugepaged: collapse_shmem() do not crash on Compound
  mm/khugepaged: collapse_shmem() without freezing new_page
  mm/khugepaged: minor reorderings in collapse_shmem()
  mm/khugepaged: collapse_shmem() remember to clear holes
  mm/khugepaged: fix crashes due to misaccounted holes
  mm/khugepaged: collapse_shmem() stop if punched or truncated
  mm/huge_memory: fix lockdep complaint on 32-bit i_size_read()
  mm/huge_memory: splitting set mapping+index before unfreeze
  mm/huge_memory: rename freeze_page() to unmap_page()
  initramfs: clean old path before creating a hardlink
  kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace
  psi: make disabling/enabling easier for vendor kernels
  proc: fixup map_files test on arm
  debugobjects: avoid recursive calls with kmemleak
  userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not set
  userfaultfd: shmem: add i_size checks
  userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas
  userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem
  ...

25 files changed, 319 insertions, 177 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 675170c360788..5d6ba930d4f46 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3505,6 +3505,10 @@
 			before loading.
 			See Documentation/blockdev/ramdisk.txt.
 
+	psi=		[KNL] Enable or disable pressure stall information
+			tracking.
+			Format: <bool>
+
 	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
 			probe for; one of (bare|imps|exps|lifebook|any).
 	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
diff --git a/MAINTAINERS b/MAINTAINERS
index b39ce1b538bc4..01645edc23885 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2491,7 +2491,7 @@ F:	drivers/net/wireless/ath/*
 ATHEROS ATH5K WIRELESS DRIVER
 M:	Jiri Slaby <jirislaby@gmail.com>
 M:	Nick Kossifidis <mickflemm@gmail.com>
-M:	"Luis R. Rodriguez" <mcgrof@do-not-panic.com>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 L:	linux-wireless@vger.kernel.org
 W:	http://wireless.kernel.org/en/users/Drivers/ath5k
 S:	Maintained
@@ -5835,7 +5835,7 @@ F:	include/uapi/linux/firewire*.h
 F:	tools/firewire/
 
 FIRMWARE LOADER (request_firmware)
-M:	Luis R. Rodriguez <mcgrof@kernel.org>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 F:	Documentation/firmware_class/
@@ -8135,7 +8135,7 @@ F:	tools/testing/selftests/
 F:	Documentation/dev-tools/kselftest*
 
 KERNEL USERMODE HELPER
-M:	"Luis R. Rodriguez" <mcgrof@kernel.org>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 F:	kernel/umh.c
@@ -8311,7 +8311,7 @@ F:	mm/kmemleak.c
 F:	mm/kmemleak-test.c
 
 KMOD KERNEL MODULE LOADER - USERMODE HELPER
-M:	"Luis R. Rodriguez" <mcgrof@kernel.org>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
 F:	kernel/kmod.c
@@ -12061,7 +12061,7 @@ F:	kernel/printk/
 F:	include/linux/printk.h
 
 PRISM54 WIRELESS DRIVER
-M:	"Luis R. Rodriguez" <mcgrof@gmail.com>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 L:	linux-wireless@vger.kernel.org
 W:	http://wireless.kernel.org/en/users/Drivers/p54
 S:	Obsolete
@@ -12075,9 +12075,10 @@ S:	Maintained
 F:	fs/proc/
 F:	include/linux/proc_fs.h
 F:	tools/testing/selftests/proc/
+F:	Documentation/filesystems/proc.txt
 
 PROC SYSCTL
-M:	"Luis R. Rodriguez" <mcgrof@kernel.org>
+M:	Luis Chamberlain <mcgrof@kernel.org>
 M:	Kees Cook <keescook@chromium.org>
 L:	linux-kernel@vger.kernel.org
 L:	linux-fsdevel@vger.kernel.org
diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c
index 98b96ffb95ed3..19017d2961734 100644
--- a/fs/hfs/btree.c
+++ b/fs/hfs/btree.c
@@ -338,13 +338,14 @@ void hfs_bmap_free(struct hfs_bnode *node)
 
 		nidx -= len * 8;
 		i = node->next;
-		hfs_bnode_put(node);
 		if (!i) {
 			/* panic */;
 			pr_crit("unable to free bnode %u. bmap not found!\n",
 				node->this);
+			hfs_bnode_put(node);
 			return;
 		}
+		hfs_bnode_put(node);
 		node = hfs_bnode_find(tree, i);
 		if (IS_ERR(node))
 			return;
diff --git a/fs/hfsplus/btree.c b/fs/hfsplus/btree.c
index 236efe51eca67..66774f4cb4fd5 100644
--- a/fs/hfsplus/btree.c
+++ b/fs/hfsplus/btree.c
@@ -466,14 +466,15 @@ void hfs_bmap_free(struct hfs_bnode *node)
 
 		nidx -= len * 8;
 		i = node->next;
-		hfs_bnode_put(node);
 		if (!i) {
 			/* panic */;
 			pr_crit("unable to free bnode %u. "
 					"bmap not found!\n",
 				node->this);
+			hfs_bnode_put(node);
 			return;
 		}
+		hfs_bnode_put(node);
 		node = hfs_bnode_find(tree, i);
 		if (IS_ERR(node))
 			return;
diff --git a/fs/ocfs2/export.c b/fs/ocfs2/export.c
index 9f88188060db9..4bf8d5854b271 100644
--- a/fs/ocfs2/export.c
+++ b/fs/ocfs2/export.c
@@ -125,10 +125,10 @@ check_err:
 
 check_gen:
 	if (handle->ih_generation != inode->i_generation) {
-		iput(inode);
 		trace_ocfs2_get_dentry_generation((unsigned long long)blkno,
 						  handle->ih_generation,
 						  inode->i_generation);
+		iput(inode);
 		result = ERR_PTR(-ESTALE);
 		goto bail;
 	}
diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 3f1685d7d43bf..1565dd8e8856e 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -157,18 +157,14 @@ out:
 }
 
 /*
- * lock allocators, and reserving appropriate number of bits for
- * meta blocks and data clusters.
- *
- * in some cases, we don't need to reserve clusters, just let data_ac
- * be NULL.
+ * lock allocator, and reserve appropriate number of bits for
+ * meta blocks.
  */
-static int ocfs2_lock_allocators_move_extents(struct inode *inode,
+static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode,
 					struct ocfs2_extent_tree *et,
 					u32 clusters_to_move,
 					u32 extents_to_split,
 					struct ocfs2_alloc_context **meta_ac,
-					struct ocfs2_alloc_context **data_ac,
 					int extra_blocks,
 					int *credits)
 {
@@ -193,13 +189,6 @@ static int ocfs2_lock_allocators_move_extents(struct inode *inode,
 		goto out;
 	}
 
-	if (data_ac) {
-		ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
-		if (ret) {
-			mlog_errno(ret);
-			goto out;
-		}
-	}
 
 	*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el);
 
@@ -259,10 +248,10 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
 		}
 	}
 
-	ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
-						 &context->meta_ac,
-						 &context->data_ac,
-						 extra_blocks, &credits);
+	ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+						*len, 1,
+						&context->meta_ac,
+						extra_blocks, &credits);
 	if (ret) {
 		mlog_errno(ret);
 		goto out;
@@ -285,6 +274,21 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
 		}
 	}
 
+	/*
+	 * Make sure ocfs2_reserve_cluster is called after
+	 * __ocfs2_flush_truncate_log, otherwise, dead lock may happen.
+	 *
+	 * If ocfs2_reserve_cluster is called
+	 * before __ocfs2_flush_truncate_log, dead lock on global bitmap
+	 * may happen.
+	 *
+	 */
+	ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_unlock_mutex;
+	}
+
 	handle = ocfs2_start_trans(osb, credits);
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);
@@ -617,9 +621,10 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
 		}
 	}
 
-	ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
-						 &context->meta_ac,
-						 NULL, extra_blocks, &credits);
+	ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+						len, 1,
+						&context->meta_ac,
+						extra_blocks, &credits);
 	if (ret) {
 		mlog_errno(ret);
 		goto out;
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 356d2b8568c14..cd58939dc977e 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1361,6 +1361,19 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		ret = -EINVAL;
 		if (!vma_can_userfault(cur))
 			goto out_unlock;
+
+		/*
+		 * UFFDIO_COPY will fill file holes even without
+		 * PROT_WRITE. This check enforces that if this is a
+		 * MAP_SHARED, the process has write permission to the backing
+		 * file. If VM_MAYWRITE is set it also enforces that on a
+		 * MAP_SHARED vma: there is no F_WRITE_SEAL and no further
+		 * F_WRITE_SEAL can be taken until the vma is destroyed.
+		 */
+		ret = -EPERM;
+		if (unlikely(!(cur->vm_flags & VM_MAYWRITE)))
+			goto out_unlock;
+
 		/*
 		 * If this vma contains ending address, and huge pages
 		 * check alignment.
@@ -1406,6 +1419,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		BUG_ON(!vma_can_userfault(vma));
 		BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
 		       vma->vm_userfaultfd_ctx.ctx != ctx);
+		WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
 
 		/*
 		 * Nothing to do: this vma is already registered into this
@@ -1552,6 +1566,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		cond_resched();
 
 		BUG_ON(!vma_can_userfault(vma));
+		WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
 
 		/*
 		 * Nothing to do: this vma is already registered into this
diff --git a/include/linux/psi.h b/include/linux/psi.h
index 8e0725aac0aa8..7006008d5b72f 100644
--- a/include/linux/psi.h
+++ b/include/linux/psi.h
@@ -1,6 +1,7 @@
 #ifndef _LINUX_PSI_H
 #define _LINUX_PSI_H
 
+#include <linux/jump_label.h>
 #include <linux/psi_types.h>
 #include <linux/sched.h>
 
@@ -9,7 +10,7 @@ struct css_set;
 
 #ifdef CONFIG_PSI
 
-extern bool psi_disabled;
+extern struct static_key_false psi_disabled;
 
 void psi_init(void);
 
diff --git a/init/Kconfig b/init/Kconfig
index a4112e95724a0..cf5b5a0dcbc2f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -509,6 +509,15 @@ config PSI
 
 	  Say N if unsure.
 
+config PSI_DEFAULT_DISABLED
+	bool "Require boot parameter to enable pressure stall information tracking"
+	default n
+	depends on PSI
+	help
+	  If set, pressure stall information tracking will be disabled
+	  per default but can be enabled through passing psi_enable=1
+	  on the kernel commandline during boot.
+
 endmenu # "CPU/Task time and stats accounting"
 
 config CPU_ISOLATION
diff --git a/init/initramfs.c b/init/initramfs.c
index 640557788026d..f6f4a1e4cd547 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -291,16 +291,6 @@ static int __init do_reset(void)
 	return 1;
 }
 
-static int __init maybe_link(void)
-{
-	if (nlink >= 2) {
-		char *old = find_link(major, minor, ino, mode, collected);
-		if (old)
-			return (ksys_link(old, collected) < 0) ? -1 : 1;
-	}
-	return 0;
-}
-
 static void __init clean_path(char *path, umode_t fmode)
 {
 	struct kstat st;
@@ -313,6 +303,18 @@ static void __init clean_path(char *path, umode_t fmode)
 	}
 }
 
+static int __init maybe_link(void)
+{
+	if (nlink >= 2) {
+		char *old = find_link(major, minor, ino, mode, collected);
+		if (old) {
+			clean_path(collected, 0);
+			return (ksys_link(old, collected) < 0) ? -1 : 1;
+		}
+	}
+	return 0;
+}
+
 static __initdata int wfd;
 
 static int __init do_name(void)
diff --git a/kernel/kcov.c b/kernel/kcov.c
index 3ebd09efe72a6..97959d7b77e2a 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -56,7 +56,7 @@ struct kcov {
 	struct task_struct	*t;
 };
 
-static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
+static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 {
 	unsigned int mode;
 
@@ -78,7 +78,7 @@ static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 	return mode == needed_mode;
 }
 
-static unsigned long canonicalize_ip(unsigned long ip)
+static notrace unsigned long canonicalize_ip(unsigned long ip)
 {
 #ifdef CONFIG_RANDOMIZE_BASE
 	ip -= kaslr_offset();
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 3d7355d7c3e38..fe24de3fbc938 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -136,8 +136,18 @@
 
 static int psi_bug __read_mostly;
 
-bool psi_disabled __read_mostly;
-core_param(psi_disabled, psi_disabled, bool, 0644);
+DEFINE_STATIC_KEY_FALSE(psi_disabled);
+
+#ifdef CONFIG_PSI_DEFAULT_DISABLED
+bool psi_enable;
+#else
+bool psi_enable = true;
+#endif
+static int __init setup_psi(char *str)
+{
+	return kstrtobool(str, &psi_enable) == 0;
+}
+__setup("psi=", setup_psi);
 
 /* Running averages - we need to be higher-res than loadavg */
 #define PSI_FREQ	(2*HZ+1)	/* 2 sec intervals */
@@ -169,8 +179,10 @@ static void group_init(struct psi_group *group)
 
 void __init psi_init(void)
 {
-	if (psi_disabled)
+	if (!psi_enable) {
+		static_branch_enable(&psi_disabled);
 		return;
+	}
 
 	psi_period = jiffies_to_nsecs(PSI_FREQ);
 	group_init(&psi_system);
@@ -549,7 +561,7 @@ void psi_memstall_enter(unsigned long *flags)
 	struct rq_flags rf;
 	struct rq *rq;
 
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	*flags = current->flags & PF_MEMSTALL;
@@ -579,7 +591,7 @@ void psi_memstall_leave(unsigned long *flags)
 	struct rq_flags rf;
 	struct rq *rq;
 
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	if (*flags)
@@ -600,7 +612,7 @@ void psi_memstall_leave(unsigned long *flags)
 #ifdef CONFIG_CGROUPS
 int psi_cgroup_alloc(struct cgroup *cgroup)
 {
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return 0;
 
 	cgroup->psi.pcpu = alloc_percpu(struct psi_group_cpu);
@@ -612,7 +624,7 @@ int psi_cgroup_alloc(struct cgroup *cgroup)
 
 void psi_cgroup_free(struct cgroup *cgroup)
 {
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	cancel_delayed_work_sync(&cgroup->psi.clock_work);
@@ -637,7 +649,7 @@ void cgroup_move_task(struct task_struct *task, struct css_set *to)
 	struct rq_flags rf;
 	struct rq *rq;
 
-	if (psi_disabled) {
+	if (static_branch_likely(&psi_disabled)) {
 		/*
 		 * Lame to do this here, but the scheduler cannot be locked
 		 * from the outside, so we move cgroups from inside sched/.
@@ -673,7 +685,7 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
 {
 	int full;
 
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return -EOPNOTSUPP;
 
 	update_stats(group);
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 4904c46770007..aa0de240fb419 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -66,7 +66,7 @@ static inline void psi_enqueue(struct task_struct *p, bool wakeup)
 {
 	int clear = 0, set = TSK_RUNNING;
 
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	if (!wakeup || p->sched_psi_wake_requeue) {
@@ -86,7 +86,7 @@ static inline void psi_dequeue(struct task_struct *p, bool sleep)
 {
 	int clear = TSK_RUNNING, set = 0;
 
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	if (!sleep) {
@@ -102,7 +102,7 @@ static inline void psi_dequeue(struct task_struct *p, bool sleep)
 
 static inline void psi_ttwu_dequeue(struct task_struct *p)
 {
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 	/*
 	 * Is the task being migrated during a wakeup? Make sure to
@@ -128,7 +128,7 @@ static inline void psi_ttwu_dequeue(struct task_struct *p)
 
 static inline void psi_task_tick(struct rq *rq)
 {
-	if (psi_disabled)
+	if (static_branch_likely(&psi_disabled))
 		return;
 
 	if (unlikely(rq->curr->flags & PF_MEMSTALL))
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 70935ed911259..14afeeb7d6ef5 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -135,7 +135,6 @@ static void fill_pool(void)
 		if (!new)
 			return;
 
-		kmemleak_ignore(new);
 		raw_spin_lock_irqsave(&pool_lock, flags);
 		hlist_add_head(&new->node, &obj_pool);
 		debug_objects_allocated++;
@@ -1128,7 +1127,6 @@ static int __init debug_objects_replace_static_objects(void)
 		obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
 		if (!obj)
 			goto free;
-		kmemleak_ignore(obj);
 		hlist_add_head(&obj->node, &objects);
 	}
 
@@ -1184,7 +1182,8 @@ void __init debug_objects_mem_init(void)
 
 	obj_cache = kmem_cache_create("debug_objects_cache",
 				      sizeof (struct debug_obj), 0,
-				      SLAB_DEBUG_OBJECTS, NULL);
+				      SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
+				      NULL);
 
 	if (!obj_cache || debug_objects_replace_static_objects()) {
 		debug_objects_enabled = 0;
diff --git a/lib/test_kmod.c b/lib/test_kmod.c
index e3ddd836491fa..d82d022111e0e 100644
--- a/lib/test_kmod.c
+++ b/lib/test_kmod.c
@@ -1214,7 +1214,6 @@ void unregister_test_dev_kmod(struct kmod_test_device *test_dev)
 
 	dev_info(test_dev->dev, "removing interface\n");
 	misc_deregister(&test_dev->misc_dev);
-	kfree(&test_dev->misc_dev.name);
 
 	mutex_unlock(&test_dev->config_mutex);
 	mutex_unlock(&test_dev->trigger_mutex);
diff --git a/mm/gup.c b/mm/gup.c
index aa43620a3270e..8cb68a50dbdf2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -702,12 +702,11 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 		if (!vma || start >= vma->vm_end) {
 			vma = find_extend_vma(mm, start);
 			if (!vma && in_gate_area(mm, start)) {
-				int ret;
 				ret = get_gate_page(mm, start & PAGE_MASK,
 						gup_flags, &vma,
 						pages ? &pages[i] : NULL);
 				if (ret)
-					return i ? : ret;
+					goto out;
 				ctx.page_mask = 0;
 				goto next_page;
 			}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 55478ab3c83be..622cced74fd90 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2350,7 +2350,7 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
 	}
 }
 
-static void freeze_page(struct page *page)
+static void unmap_page(struct page *page)
 {
 	enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
 		TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
@@ -2365,7 +2365,7 @@ static void freeze_page(struct page *page)
 	VM_BUG_ON_PAGE(!unmap_success, page);
 }
 
-static void unfreeze_page(struct page *page)
+static void remap_page(struct page *page)
 {
 	int i;
 	if (PageTransHuge(page)) {
@@ -2402,6 +2402,12 @@ static void __split_huge_page_tail(struct page *head, int tail,
 			 (1L << PG_unevictable) |
 			 (1L << PG_dirty)));
 
+	/* ->mapping in first tail page is compound_mapcount */
+	VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
+			page_tail);
+	page_tail->mapping = head->mapping;
+	page_tail->index = head->index + tail;
+
 	/* Page flags must be visible before we make the page non-compound. */
 	smp_wmb();
 
@@ -2422,12 +2428,6 @@ static void __split_huge_page_tail(struct page *head, int tail,
 	if (page_is_idle(head))
 		set_page_idle(page_tail);
 
-	/* ->mapping in first tail page is compound_mapcount */
-	VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
-			page_tail);
-	page_tail->mapping = head->mapping;
-
-	page_tail->index = head->index + tail;
 	page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
 
 	/*
@@ -2439,12 +2439,11 @@ static void __split_huge_page_tail(struct page *head, int tail,
 }
 
 static void __split_huge_page(struct page *page, struct list_head *list,
-		unsigned long flags)
+		pgoff_t end, unsigned long flags)
 {
 	struct page *head = compound_head(page);
 	struct zone *zone = page_zone(head);
 	struct lruvec *lruvec;
-	pgoff_t end = -1;
 	int i;
 
 	lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
@@ -2452,9 +2451,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	/* complete memcg works before add pages to LRU */
 	mem_cgroup_split_huge_fixup(head);
 
-	if (!PageAnon(page))
-		end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
-
 	for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
 		__split_huge_page_tail(head, i, lruvec, list);
 		/* Some pages can be beyond i_size: drop them from page cache */
@@ -2483,7 +2479,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 	spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
 
-	unfreeze_page(head);
+	remap_page(head);
 
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
 		struct page *subpage = head + i;
@@ -2626,6 +2622,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	int count, mapcount, extra_pins, ret;
 	bool mlocked;
 	unsigned long flags;
+	pgoff_t end;
 
 	VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
@@ -2648,6 +2645,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 			ret = -EBUSY;
 			goto out;
 		}
+		end = -1;
 		mapping = NULL;
 		anon_vma_lock_write(anon_vma);
 	} else {
@@ -2661,10 +2659,19 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 
 		anon_vma = NULL;
 		i_mmap_lock_read(mapping);
+
+		/*
+		 *__split_huge_page() may need to trim off pages beyond EOF:
+		 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
+		 * which cannot be nested inside the page tree lock. So note
+		 * end now: i_size itself may be changed at any moment, but
+		 * head page lock is good enough to serialize the trimming.
+		 */
+		end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
 	}
 
 	/*
-	 * Racy check if we can split the page, before freeze_page() will
+	 * Racy check if we can split the page, before unmap_page() will
 	 * split PMDs
 	 */
 	if (!can_split_huge_page(head, &extra_pins)) {
@@ -2673,7 +2680,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	}
 
 	mlocked = PageMlocked(page);
-	freeze_page(head);
+	unmap_page(head);
 	VM_BUG_ON_PAGE(compound_mapcount(head), head);
 
 	/* Make sure the page is not on per-CPU pagevec as it takes pin */
@@ -2707,7 +2714,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		if (mapping)
 			__dec_node_page_state(page, NR_SHMEM_THPS);
 		spin_unlock(&pgdata->split_queue_lock);
-		__split_huge_page(page, list, flags);
+		__split_huge_page(page, list, end, flags);
 		if (PageSwapCache(head)) {
 			swp_entry_t entry = { .val = page_private(head) };
 
@@ -2727,7 +2734,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 fail:		if (mapping)
 			xa_unlock(&mapping->i_pages);
 		spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
-		unfreeze_page(head);
+		remap_page(head);
 		ret = -EBUSY;
 	}
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7f2a28ab46d53..705a3e9cc910e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4080,7 +4080,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 
 		/* fallback to copy_from_user outside mmap_sem */
 		if (unlikely(ret)) {
-			ret = -EFAULT;
+			ret = -ENOENT;
 			*pagep = page;
 			/* don't free the page */
 			goto out;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index c13625c1ad5e5..8e2ff195ecb30 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1287,7 +1287,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
  * collapse_shmem - collapse small tmpfs/shmem pages into huge one.
  *
  * Basic scheme is simple, details are more complex:
- *  - allocate and freeze a new huge page;
+ *  - allocate and lock a new huge page;
  *  - scan page cache replacing old pages with the new one
  *    + swap in pages if necessary;
  *    + fill in gaps;
@@ -1295,11 +1295,11 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
  *  - if replacing succeeds:
  *    + copy data over;
  *    + free old pages;
- *    + unfreeze huge page;
+ *    + unlock huge page;
  *  - if replacing failed;
  *    + put all pages back and unfreeze them;
  *    + restore gaps in the page cache;
- *    + free huge page;
+ *    + unlock and free huge page;
  */
 static void collapse_shmem(struct mm_struct *mm,
 		struct address_space *mapping, pgoff_t start,
@@ -1329,19 +1329,6 @@ static void collapse_shmem(struct mm_struct *mm,
 		goto out;
 	}
 
-	new_page->index = start;
-	new_page->mapping = mapping;
-	__SetPageSwapBacked(new_page);
-	__SetPageLocked(new_page);
-	BUG_ON(!page_ref_freeze(new_page, 1));
-
-	/*
-	 * At this point the new_page is 'frozen' (page_count() is zero),
-	 * locked and not up-to-date. It's safe to insert it into the page
-	 * cache, because nobody would be able to map it or use it in other
-	 * way until we unfreeze it.
-	 */
-
 	/* This will be less messy when we use multi-index entries */
 	do {
 		xas_lock_irq(&xas);
@@ -1349,19 +1336,44 @@ static void collapse_shmem(struct mm_struct *mm,
 		if (!xas_error(&xas))
 			break;
 		xas_unlock_irq(&xas);
-		if (!xas_nomem(&xas, GFP_KERNEL))
+		if (!xas_nomem(&xas, GFP_KERNEL)) {
+			mem_cgroup_cancel_charge(new_page, memcg, true);
+			result = SCAN_FAIL;
 			goto out;
+		}
 	} while (1);
 
+	__SetPageLocked(new_page);
+	__SetPageSwapBacked(new_page);
+	new_page->index = start;
+	new_page->mapping = mapping;
+
+	/*
+	 * At this point the new_page is locked and not up-to-date.
+	 * It's safe to insert it into the page cache, because nobody would
+	 * be able to map it or use it in another way until we unlock it.
+	 */
+
 	xas_set(&xas, start);
 	for (index = start; index < end; index++) {
 		struct page *page = xas_next(&xas);
 
 		VM_BUG_ON(index != xas.xa_index);
 		if (!page) {
+			/*
+			 * Stop if extent has been truncated or hole-punched,
+			 * and is now completely empty.
+			 */
+			if (index == start) {
+				if (!xas_next_entry(&xas, end - 1)) {
+					result = SCAN_TRUNCATED;
+					goto xa_locked;
+				}
+				xas_set(&xas, index);
+			}
 			if (!shmem_charge(mapping->host, 1)) {
 				result = SCAN_FAIL;
-				break;
+				goto xa_locked;
 			}
 			xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
 			nr_none++;
@@ -1376,13 +1388,12 @@ static void collapse_shmem(struct mm_struct *mm,
 				result = SCAN_FAIL;
 				goto xa_unlocked;
 			}
-			xas_lock_irq(&xas);
-			xas_set(&xas, index);
 		} else if (trylock_page(page)) {
 			get_page(page);
+			xas_unlock_irq(&xas);
 		} else {
 			result = SCAN_PAGE_LOCK;
-			break;
+			goto xa_locked;
 		}
 
 		/*
@@ -1391,17 +1402,24 @@ static void collapse_shmem(struct mm_struct *mm,
 		 */
 		VM_BUG_ON_PAGE(!PageLocked(page), page);
 		VM_BUG_ON_PAGE(!PageUptodate(page), page);
-		VM_BUG_ON_PAGE(PageTransCompound(page), page);
+
+		/*
+		 * If file was truncated then extended, or hole-punched, before
+		 * we locked the first page, then a THP might be there already.
+		 */
+		if (PageTransCompound(page)) {
+			result = SCAN_PAGE_COMPOUND;
+			goto out_unlock;
+		}
 
 		if (page_mapping(page) != mapping) {
 			result = SCAN_TRUNCATED;
 			goto out_unlock;
 		}
-		xas_unlock_irq(&xas);
 
 		if (isolate_lru_page(page)) {
 			result = SCAN_DEL_PAGE_LRU;
-			goto out_isolate_failed;
+			goto out_unlock;
 		}
 
 		if (page_mapped(page))
@@ -1421,7 +1439,9 @@ static void collapse_shmem(struct mm_struct *mm,
 		 */
 		if (!page_ref_freeze(page, 3)) {
 			result = SCAN_PAGE_COUNT;
-			goto out_lru;
+			xas_unlock_irq(&xas);
+			putback_lru_page(page);
+			goto out_unlock;
 		}
 
 		/*
@@ -1433,71 +1453,74 @@ static void collapse_shmem(struct mm_struct *mm,
 		/* Finally, replace with the new page. */
 		xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
 		continue;
-out_lru:
-		xas_unlock_irq(&xas);
-		putback_lru_page(page);
-out_isolate_failed:
-		unlock_page(page);
-		put_page(page);
-		goto xa_unlocked;
 out_unlock:
 		unlock_page(page);
 		put_page(page);
-		break;
+		goto xa_unlocked;
 	}
-	xas_unlock_irq(&xas);
 
+	__inc_node_page_state(new_page, NR_SHMEM_THPS);
+	if (nr_none) {
+		struct zone *zone = page_zone(new_page);
+
+		__mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
+		__mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
+	}
+
+xa_locked:
+	xas_unlock_irq(&xas);
 xa_unlocked:
+
 	if (result == SCAN_SUCCEED) {
 		struct page *page, *tmp;
-		struct zone *zone = page_zone(new_page);
 
 		/*
 		 * Replacing old pages with new one has succeeded, now we
 		 * need to copy the content and free the old pages.
 		 */
+		index = start;
 		list_for_each_entry_safe(page, tmp, &pagelist, lru) {
+			while (index < page->index) {
+				clear_highpage(new_page + (index % HPAGE_PMD_NR));
+				index++;
+			}
 			copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
 					page);
 			list_del(&page->lru);
-			unlock_page(page);
-			page_ref_unfreeze(page, 1);
 			page->mapping = NULL;
+			page_ref_unfreeze(page, 1);
 			ClearPageActive(page);
 			ClearPageUnevictable(page);
+			unlock_page(page);
 			put_page(page);
+			index++;
 		}
-
-		local_irq_disable();
-		__inc_node_page_state(new_page, NR_SHMEM_THPS);
-		if (nr_none) {
-			__mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
-			__mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
+		while (index < end) {
+			clear_highpage(new_page + (index % HPAGE_PMD_NR));
+			index++;
 		}
-		local_irq_enable();
 
-		/*
-		 * Remove pte page tables, so we can re-fault
-		 * the page as huge.
-		 */
-		retract_page_tables(mapping, start);
-
-		/* Everything is ready, let's unfreeze the new_page */
-		set_page_dirty(new_page);
 		SetPageUptodate(new_page);
-		page_ref_unfreeze(new_page, HPAGE_PMD_NR);
+		page_ref_add(new_page, HPAGE_PMD_NR - 1);
+		set_page_dirty(new_page);
 		mem_cgroup_commit_charge(new_page, memcg, false, true);
 		lru_cache_add_anon(new_page);
-		unlock_page(new_page);
 
+		/*
+		 * Remove pte page tables, so we can re-fault the page as huge.
+		 */
+		retract_page_tables(mapping, start);
 		*hpage = NULL;
 
 		khugepaged_pages_collapsed++;
 	} else {
 		struct page *page;
+
 		/* Something went wrong: roll back page cache changes */
-		shmem_uncharge(mapping->host, nr_none);
 		xas_lock_irq(&xas);
+		mapping->nrpages -= nr_none;
+		shmem_uncharge(mapping->host, nr_none);
+
 		xas_set(&xas, start);
 		xas_for_each(&xas, page, end - 1) {
 			page = list_first_entry_or_null(&pagelist,
@@ -1519,19 +1542,18 @@ xa_unlocked:
 			xas_store(&xas, page);
 			xas_pause(&xas);
 			xas_unlock_irq(&xas);
-			putback_lru_page(page);
 			unlock_page(page);
+			putback_lru_page(page);
 			xas_lock_irq(&xas);
 		}
 		VM_BUG_ON(nr_none);
 		xas_unlock_irq(&xas);
 
-		/* Unfreeze new_page, caller would take care about freeing it */
-		page_ref_unfreeze(new_page, 1);
 		mem_cgroup_cancel_charge(new_page, memcg, true);
-		unlock_page(new_page);
 		new_page->mapping = NULL;
 	}
+
+	unlock_page(new_page);
 out:
 	VM_BUG_ON(!list_empty(&pagelist));
 	/* TODO: tracepoints */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6847177dc4a1a..2ec9cc4072165 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5813,8 +5813,10 @@ void __meminit init_currently_empty_zone(struct zone *zone,
 					unsigned long size)
 {
 	struct pglist_data *pgdat = zone->zone_pgdat;
+	int zone_idx = zone_idx(zone) + 1;
 
-	pgdat->nr_zones = zone_idx(zone) + 1;
+	if (zone_idx > pgdat->nr_zones)
+		pgdat->nr_zones = zone_idx;
 
 	zone->zone_start_pfn = zone_start_pfn;
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 1e79fac3186b6..85b7f94233526 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1627,16 +1627,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 						      address + PAGE_SIZE);
 		} else {
 			/*
-			 * We should not need to notify here as we reach this
-			 * case only from freeze_page() itself only call from
-			 * split_huge_page_to_list() so everything below must
-			 * be true:
-			 *   - page is not anonymous
-			 *   - page is locked
-			 *
-			 * So as it is a locked file back page thus it can not
-			 * be remove from the page cache and replace by a new
-			 * page before mmu_notifier_invalidate_range_end so no
+			 * This is a locked file-backed page, thus it cannot
+			 * be removed from the page cache and replaced by a new
+			 * page before mmu_notifier_invalidate_range_end, so no
 			 * concurrent thread might update its page table to
 			 * point at new page while a device still is using this
 			 * page.
diff --git a/mm/shmem.c b/mm/shmem.c
index d44991ea5ed4b..cddc72ac44d86 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -297,12 +297,14 @@ bool shmem_charge(struct inode *inode, long pages)
 	if (!shmem_inode_acct_block(inode, pages))
 		return false;
 
+	/* nrpages adjustment first, then shmem_recalc_inode() when balanced */
+	inode->i_mapping->nrpages += pages;
+
 	spin_lock_irqsave(&info->lock, flags);
 	info->alloced += pages;
 	inode->i_blocks += pages * BLOCKS_PER_PAGE;
 	shmem_recalc_inode(inode);
 	spin_unlock_irqrestore(&info->lock, flags);
-	inode->i_mapping->nrpages += pages;
 
 	return true;
 }
@@ -312,6 +314,8 @@ void shmem_uncharge(struct inode *inode, long pages)
 	struct shmem_inode_info *info = SHMEM_I(inode);
 	unsigned long flags;
 
+	/* nrpages adjustment done by __delete_from_page_cache() or caller */
+
 	spin_lock_irqsave(&info->lock, flags);
 	info->alloced -= pages;
 	inode->i_blocks -= pages * BLOCKS_PER_PAGE;
@@ -1509,11 +1513,13 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 {
 	struct page *oldpage, *newpage;
 	struct address_space *swap_mapping;
+	swp_entry_t entry;
 	pgoff_t swap_index;
 	int error;
 
 	oldpage = *pagep;
-	swap_index = page_private(oldpage);
+	entry.val = page_private(oldpage);
+	swap_index = swp_offset(entry);
 	swap_mapping = page_mapping(oldpage);
 
 	/*
@@ -1532,7 +1538,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 	__SetPageLocked(newpage);
 	__SetPageSwapBacked(newpage);
 	SetPageUptodate(newpage);
-	set_page_private(newpage, swap_index);
+	set_page_private(newpage, entry.val);
 	SetPageSwapCache(newpage);
 
 	/*
@@ -2214,6 +2220,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 	struct page *page;
 	pte_t _dst_pte, *dst_pte;
 	int ret;
+	pgoff_t offset, max_off;
 
 	ret = -ENOMEM;
 	if (!shmem_inode_acct_block(inode, 1))
@@ -2236,7 +2243,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 				*pagep = page;
 				shmem_inode_unacct_blocks(inode, 1);
 				/* don't free the page */
-				return -EFAULT;
+				return -ENOENT;
 			}
 		} else {		/* mfill_zeropage_atomic */
 			clear_highpage(page);
@@ -2251,6 +2258,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 	__SetPageSwapBacked(page);
 	__SetPageUptodate(page);
 
+	ret = -EFAULT;
+	offset = linear_page_index(dst_vma, dst_addr);
+	max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+	if (unlikely(offset >= max_off))
+		goto out_release;
+
 	ret = mem_cgroup_try_charge_delay(page, dst_mm, gfp, &memcg, false);
 	if (ret)
 		goto out_release;
@@ -2265,9 +2278,25 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 	_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
 	if (dst_vma->vm_flags & VM_WRITE)
 		_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
+	else {
+		/*
+		 * We don't set the pte dirty if the vma has no
+		 * VM_WRITE permission, so mark the page dirty or it
+		 * could be freed from under us. We could do it
+		 * unconditionally before unlock_page(), but doing it
+		 * only if VM_WRITE is not set is faster.
+		 */
+		set_page_dirty(page);
+	}
 
-	ret = -EEXIST;
 	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+
+	ret = -EFAULT;
+	max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+	if (unlikely(offset >= max_off))
+		goto out_release_uncharge_unlock;
+
+	ret = -EEXIST;
 	if (!pte_none(*dst_pte))
 		goto out_release_uncharge_unlock;
 
@@ -2285,13 +2314,15 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 
 	/* No need to invalidate - it was non-present before */
 	update_mmu_cache(dst_vma, dst_addr, dst_pte);
-	unlock_page(page);
 	pte_unmap_unlock(dst_pte, ptl);
+	unlock_page(page);
 	ret = 0;
 out:
 	return ret;
 out_release_uncharge_unlock:
 	pte_unmap_unlock(dst_pte, ptl);
+	ClearPageDirty(page);
+	delete_from_page_cache(page);
 out_release_uncharge:
 	mem_cgroup_cancel_charge(page, memcg, false);
 out_release:
diff --git a/mm/truncate.c b/mm/truncate.c
index 45d68e90b7037..798e7ccfb030b 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -517,9 +517,13 @@ void truncate_inode_pages_final(struct address_space *mapping)
 		 */
 		xa_lock_irq(&mapping->i_pages);
 		xa_unlock_irq(&mapping->i_pages);
-
-		truncate_inode_pages(mapping, 0);
 	}
+
+	/*
+	 * Cleancache needs notification even if there are no pages or shadow
+	 * entries.
+	 */
+	truncate_inode_pages(mapping, 0);
 }
 EXPORT_SYMBOL(truncate_inode_pages_final);
 
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 5029f241908f4..458acda96f207 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -33,6 +33,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
 	void *page_kaddr;
 	int ret;
 	struct page *page;
+	pgoff_t offset, max_off;
+	struct inode *inode;
 
 	if (!*pagep) {
 		ret = -ENOMEM;
@@ -48,7 +50,7 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
 
 		/* fallback to copy_from_user outside mmap_sem */
 		if (unlikely(ret)) {
-			ret = -EFAULT;
+			ret = -ENOENT;
 			*pagep = page;
 			/* don't free the page */
 			goto out;
@@ -73,8 +75,17 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
 	if (dst_vma->vm_flags & VM_WRITE)
 		_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
 
-	ret = -EEXIST;
 	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+	if (dst_vma->vm_file) {
+		/* the shmem MAP_PRIVATE case requires checking the i_size */
+		inode = dst_vma->vm_file->f_inode;
+		offset = linear_page_index(dst_vma, dst_addr);
+		max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+		ret = -EFAULT;
+		if (unlikely(offset >= max_off))
+			goto out_release_uncharge_unlock;
+	}
+	ret = -EEXIST;
 	if (!pte_none(*dst_pte))
 		goto out_release_uncharge_unlock;
 
@@ -108,11 +119,22 @@ static int mfill_zeropage_pte(struct mm_struct *dst_mm,
 	pte_t _dst_pte, *dst_pte;
 	spinlock_t *ptl;
 	int ret;
+	pgoff_t offset, max_off;
+	struct inode *inode;
 
 	_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
 					 dst_vma->vm_page_prot));
-	ret = -EEXIST;
 	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
+	if (dst_vma->vm_file) {
+		/* the shmem MAP_PRIVATE case requires checking the i_size */
+		inode = dst_vma->vm_file->f_inode;
+		offset = linear_page_index(dst_vma, dst_addr);
+		max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+		ret = -EFAULT;
+		if (unlikely(offset >= max_off))
+			goto out_unlock;
+	}
+	ret = -EEXIST;
 	if (!pte_none(*dst_pte))
 		goto out_unlock;
 	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
@@ -205,8 +227,9 @@ retry:
 		if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
 			goto out_unlock;
 		/*
-		 * Only allow __mcopy_atomic_hugetlb on userfaultfd
-		 * registered ranges.
+		 * Check the vma is registered in uffd, this is
+		 * required to enforce the VM_MAYWRITE check done at
+		 * uffd registration time.
 		 */
 		if (!dst_vma->vm_userfaultfd_ctx.ctx)
 			goto out_unlock;
@@ -274,7 +297,7 @@ retry:
 
 		cond_resched();
 
-		if (unlikely(err == -EFAULT)) {
+		if (unlikely(err == -ENOENT)) {
 			up_read(&dst_mm->mmap_sem);
 			BUG_ON(!page);
 
@@ -380,7 +403,17 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
 {
 	ssize_t err;
 
-	if (vma_is_anonymous(dst_vma)) {
+	/*
+	 * The normal page fault path for a shmem will invoke the
+	 * fault, fill the hole in the file and COW it right away. The
+	 * result generates plain anonymous memory. So when we are
+	 * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll
+	 * generate anonymous memory directly without actually filling
+	 * the hole. For the MAP_PRIVATE case the robustness check
+	 * only happens in the pagetable (to verify it's still none)
+	 * and not in the radix tree.
+	 */
+	if (!(dst_vma->vm_flags & VM_SHARED)) {
 		if (!zeropage)
 			err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
 					       dst_addr, src_addr, page);
@@ -449,13 +482,9 @@ retry:
 	if (!dst_vma)
 		goto out_unlock;
 	/*
-	 * Be strict and only allow __mcopy_atomic on userfaultfd
-	 * registered ranges to prevent userland errors going
-	 * unnoticed. As far as the VM consistency is concerned, it
-	 * would be perfectly safe to remove this check, but there's
-	 * no useful usage for __mcopy_atomic ouside of userfaultfd
-	 * registered ranges. This is after all why these are ioctls
-	 * belonging to the userfaultfd and not syscalls.
+	 * Check the vma is registered in uffd, this is required to
+	 * enforce the VM_MAYWRITE check done at uffd registration
+	 * time.
 	 */
 	if (!dst_vma->vm_userfaultfd_ctx.ctx)
 		goto out_unlock;
@@ -489,7 +518,8 @@ retry:
 	 * dst_vma.
 	 */
 	err = -ENOMEM;
-	if (vma_is_anonymous(dst_vma) && unlikely(anon_vma_prepare(dst_vma)))
+	if (!(dst_vma->vm_flags & VM_SHARED) &&
+	    unlikely(anon_vma_prepare(dst_vma)))
 		goto out_unlock;
 
 	while (src_addr < src_start + len) {
@@ -530,7 +560,7 @@ retry:
 				       src_addr, &page, zeropage);
 		cond_resched();
 
-		if (unlikely(err == -EFAULT)) {
+		if (unlikely(err == -ENOENT)) {
 			void *page_kaddr;
 
 			up_read(&dst_mm->mmap_sem);
diff --git a/tools/testing/selftests/proc/proc-self-map-files-002.c b/tools/testing/selftests/proc/proc-self-map-files-002.c
index 6f1f4a6e1ecb1..85744425b08d3 100644
--- a/tools/testing/selftests/proc/proc-self-map-files-002.c
+++ b/tools/testing/selftests/proc/proc-self-map-files-002.c
@@ -13,7 +13,7 @@
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
-/* Test readlink /proc/self/map_files/... with address 0. */
+/* Test readlink /proc/self/map_files/... with minimum address. */
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -47,6 +47,11 @@ static void fail(const char *fmt, unsigned long a, unsigned long b)
 int main(void)
 {
 	const unsigned int PAGE_SIZE = sysconf(_SC_PAGESIZE);
+#ifdef __arm__
+	unsigned long va = 2 * PAGE_SIZE;
+#else
+	unsigned long va = 0;
+#endif
 	void *p;
 	int fd;
 	unsigned long a, b;
@@ -55,7 +60,7 @@ int main(void)
 	if (fd == -1)
 		return 1;
 
-	p = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE|MAP_FIXED, fd, 0);
+	p = mmap((void *)va, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE|MAP_FIXED, fd, 0);
 	if (p == MAP_FAILED) {
 		if (errno == EPERM)
 			return 2;