Merge tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "This contains the usual selections of misc updates for this cycle.

  Features:

   - Add "initramfs_options" parameter to set initramfs mount options.
     This allows to add specific mount options to the rootfs to e.g.,
     limit the memory size

   - Add RWF_NOSIGNAL flag for pwritev2()

     Add RWF_NOSIGNAL flag for pwritev2. This flag prevents the SIGPIPE
     signal from being raised when writing on disconnected pipes or
     sockets. The flag is handled directly by the pipe filesystem and
     converted to the existing MSG_NOSIGNAL flag for sockets

   - Allow to pass pid namespace as procfs mount option

     Ever since the introduction of pid namespaces, procfs has had very
     implicit behaviour surrounding them (the pidns used by a procfs
     mount is auto-selected based on the mounting process's active
     pidns, and the pidns itself is basically hidden once the mount has
     been constructed)

     This implicit behaviour has historically meant that userspace was
     required to do some special dances in order to configure the pidns
     of a procfs mount as desired. Examples include:

     * In order to bypass the mnt_too_revealing() check, Kubernetes
       creates a procfs mount from an empty pidns so that user
       namespaced containers can be nested (without this, the nested
       containers would fail to mount procfs)

       But this requires forking off a helper process because you cannot
       just one-shot this using mount(2)

     * Container runtimes in general need to fork into a container
       before configuring its mounts, which can lead to security issues
       in the case of shared-pidns containers (a privileged process in
       the pidns can interact with your container runtime process)

       While SUID_DUMP_DISABLE and user namespaces make this less of an
       issue, the strict need for this due to a minor uAPI wart is kind
       of unfortunate

       Things would be much easier if there was a way for userspace to
       just specify the pidns they want. So this pull request contains
       changes to implement a new "pidns" argument which can be set
       using fsconfig(2):

           fsconfig(procfd, FSCONFIG_SET_FD, "pidns", NULL, nsfd);
           fsconfig(procfd, FSCONFIG_SET_STRING, "pidns", "/proc/self/ns/pid", 0);

       or classic mount(2) / mount(8):

           // mount -t proc -o pidns=/proc/self/ns/pid proc /tmp/proc
           mount("proc", "/tmp/proc", "proc", MS_..., "pidns=/proc/self/ns/pid");

  Cleanups:

   - Remove the last references to EXPORT_OP_ASYNC_LOCK

   - Make file_remove_privs_flags() static

   - Remove redundant __GFP_NOWARN when GFP_NOWAIT is used

   - Use try_cmpxchg() in start_dir_add()

   - Use try_cmpxchg() in sb_init_done_wq()

   - Replace offsetof() with struct_size() in ioctl_file_dedupe_range()

   - Remove vfs_ioctl() export

   - Replace rwlock() with spinlock in epoll code as rwlock causes
     priority inversion on preempt rt kernels

   - Make ns_entries in fs/proc/namespaces const

   - Use a switch() statement() in init_special_inode() just like we do
     in may_open()

   - Use struct_size() in dir_add() in the initramfs code

   - Use str_plural() in rd_load_image()

   - Replace strcpy() with strscpy() in find_link()

   - Rename generic_delete_inode() to inode_just_drop() and
     generic_drop_inode() to inode_generic_drop()

   - Remove unused arguments from fcntl_{g,s}et_rw_hint()

  Fixes:

   - Document @name parameter for name_contains_dotdot() helper

   - Fix spelling mistake

   - Always return zero from replace_fd() instead of the file descriptor
     number

   - Limit the size for copy_file_range() in compat mode to prevent a
     signed overflow

   - Fix debugfs mount options not being applied

   - Verify the inode mode when loading it from disk in minixfs

   - Verify the inode mode when loading it from disk in cramfs

   - Don't trigger automounts with RESOLVE_NO_XDEV

     If openat2() was called with RESOLVE_NO_XDEV it didn't traverse
     through automounts, but could still trigger them

   - Add FL_RECLAIM flag to show_fl_flags() macro so it appears in
     tracepoints

   - Fix unused variable warning in rd_load_image() on s390

   - Make INITRAMFS_PRESERVE_MTIME depend on BLK_DEV_INITRD

   - Use ns_capable_noaudit() when determining net sysctl permissions

   - Don't call path_put() under namespace semaphore in listmount() and
     statmount()"

* tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (38 commits)
  fcntl: trim arguments
  listmount: don't call path_put() under namespace semaphore
  statmount: don't call path_put() under namespace semaphore
  pid: use ns_capable_noaudit() when determining net sysctl permissions
  fs: rename generic_delete_inode() and generic_drop_inode()
  init: INITRAMFS_PRESERVE_MTIME should depend on BLK_DEV_INITRD
  initramfs: Replace strcpy() with strscpy() in find_link()
  initrd: Use str_plural() in rd_load_image()
  initramfs: Use struct_size() helper to improve dir_add()
  initrd: Fix unused variable warning in rd_load_image() on s390
  fs: use the switch statement in init_special_inode()
  fs/proc/namespaces: make ns_entries const
  filelock: add FL_RECLAIM to show_fl_flags() macro
  eventpoll: Replace rwlock with spinlock
  selftests/proc: add tests for new pidns APIs
  procfs: add "pidns" mount option
  pidns: move is-ancestor logic to helper
  openat2: don't trigger automounts with RESOLVE_NO_XDEV
  namei: move cross-device check to __traverse_mounts
  namei: remove LOOKUP_NO_XDEV check from handle_mounts
  ...

64 files changed, 582 insertions, 264 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 5a7a83c411e9..e92c0056e4e0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6429,6 +6429,9 @@
 
 	rootflags=	[KNL] Set root filesystem mount option string
 
+	initramfs_options= [KNL]
+                        Specify mount options for for the initramfs mount.
+
 	rootfstype=	[KNL] Set root filesystem type
 
 	rootwait	[KNL] Wait (indefinitely) for root device to show up.
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 85f590254f07..b5db45c0094c 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -340,8 +340,8 @@ of those. Caller makes sure async writeback cannot be running for the inode whil
 
 ->drop_inode() returns int now; it's called on final iput() with
 inode->i_lock held and it returns true if filesystems wants the inode to be
-dropped.  As before, generic_drop_inode() is still the default and it's been
-updated appropriately.  generic_delete_inode() is also alive and it consists
+dropped.  As before, inode_generic_drop() is still the default and it's been
+updated appropriately.  inode_just_drop() is also alive and it consists
 simply of return 1.  Note that all actual eviction work is done by caller after
 ->drop_inode() returns.
 
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 2971551b7235..b7e3147ba3d4 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -2362,6 +2362,7 @@ The following mount options are supported:
 	hidepid=	Set /proc/<pid>/ access mode.
 	gid=		Set the group authorized to learn processes information.
 	subset=		Show only the specified subset of procfs.
+	pidns=		Specify a the namespace used by this procfs.
 	=========	========================================================
 
 hidepid=off or hidepid=0 means classic mode - everybody may access all
@@ -2394,6 +2395,13 @@ information about processes information, just add identd to this group.
 subset=pid hides all top level files and directories in the procfs that
 are not related to tasks.
 
+pidns= specifies a pid namespace (either as a string path to something like
+`/proc/$pid/ns/pid`, or a file descriptor when using `FSCONFIG_SET_FD`) that
+will be used by the procfs instance when translating pids. By default, procfs
+will use the calling process's active pid namespace. Note that the pid
+namespace of an existing procfs instance cannot be modified (attempting to do
+so will give an `-EBUSY` error).
+
 Chapter 5: Filesystem behavior
 ==============================
 
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 486a91633474..7a314eee6305 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -327,11 +327,11 @@ or bottom half).
 	inode->i_lock spinlock held.
 
 	This method should be either NULL (normal UNIX filesystem
-	semantics) or "generic_delete_inode" (for filesystems that do
+	semantics) or "inode_just_drop" (for filesystems that do
 	not want to cache inodes - causing "delete_inode" to always be
 	called regardless of the value of i_nlink)
 
-	The "generic_delete_inode()" behavior is equivalent to the old
+	The "inode_just_drop()" behavior is equivalent to the old
 	practice of using "force_delete" in the put_inode() case, but
 	does not have the races that the "force_delete()" approach had.
 
diff --git a/block/bdev.c b/block/bdev.c
index b77ddd12dc06..810707cca970 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -412,7 +412,7 @@ static const struct super_operations bdev_sops = {
 	.statfs = simple_statfs,
 	.alloc_inode = bdev_alloc_inode,
 	.free_inode = bdev_free_inode,
-	.drop_inode = generic_delete_inode,
+	.drop_inode = inode_just_drop,
 	.evict_inode = bdev_evict_inode,
 };
 
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 54c480e874cb..d7714d8afb0f 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -388,7 +388,7 @@ static const struct super_operations dax_sops = {
 	.alloc_inode = dax_alloc_inode,
 	.destroy_inode = dax_destroy_inode,
 	.free_inode = dax_free_inode,
-	.drop_inode = generic_delete_inode,
+	.drop_inode = inode_just_drop,
 };
 
 static int dax_init_fs_context(struct fs_context *fc)
diff --git a/drivers/misc/ibmasm/ibmasmfs.c b/drivers/misc/ibmasm/ibmasmfs.c
index c44de892a61e..5372ed2a363e 100644
--- a/drivers/misc/ibmasm/ibmasmfs.c
+++ b/drivers/misc/ibmasm/ibmasmfs.c
@@ -94,7 +94,7 @@ static int ibmasmfs_init_fs_context(struct fs_context *fc)
 
 static const struct super_operations ibmasmfs_s_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 };
 
 static const struct file_operations *ibmasmfs_dir_ops = &simple_dir_operations;
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 08a251df20c4..5246fa6af3d6 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -1891,7 +1891,7 @@ static struct dentry *ffs_sb_create_file(struct super_block *sb,
 /* Super block */
 static const struct super_operations ffs_sb_operations = {
 	.statfs =	simple_statfs,
-	.drop_inode =	generic_delete_inode,
+	.drop_inode =	inode_just_drop,
 };
 
 struct ffs_sb_fill_data {
diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index b51e132b0cd2..13c3da49348c 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -2011,7 +2011,7 @@ gadgetfs_create_file (struct super_block *sb, char const *name,
 
 static const struct super_operations gadget_fs_operations = {
 	.statfs =	simple_statfs,
-	.drop_inode =	generic_delete_inode,
+	.drop_inode =	inode_just_drop,
 };
 
 static int
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 795c6388744c..1581ebac5bb4 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -252,7 +252,7 @@ static int v9fs_drop_inode(struct inode *inode)
 
 	v9ses = v9fs_inode2v9ses(inode);
 	if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
-		return generic_drop_inode(inode);
+		return inode_generic_drop(inode);
 	/*
 	 * in case of non cached mode always drop the
 	 * inode because we want the inode attribute
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index e9538e91f848..e1cb17b85791 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -723,9 +723,9 @@ int afs_drop_inode(struct inode *inode)
 	_enter("");
 
 	if (test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(inode)->flags))
-		return generic_delete_inode(inode);
+		return inode_just_drop(inode);
 	else
-		return generic_drop_inode(inode);
+		return inode_generic_drop(inode);
 }
 
 /*
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 18db1053cdf0..3923be975e47 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7973,7 +7973,7 @@ int btrfs_drop_inode(struct inode *inode)
 	if (btrfs_root_refs(&root->root_item) == 0)
 		return 1;
 	else
-		return generic_drop_inode(inode);
+		return inode_generic_drop(inode);
 }
 
 static void init_once(void *foo)
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index c3eb651862c5..70dc9467f6a0 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -1042,7 +1042,7 @@ static const struct super_operations ceph_super_ops = {
 	.alloc_inode	= ceph_alloc_inode,
 	.free_inode	= ceph_free_inode,
 	.write_inode    = ceph_write_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= ceph_evict_inode,
 	.sync_fs        = ceph_sync_fs,
 	.put_super	= ceph_put_super,
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 740f18b60c9d..456c4a2efb53 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -36,7 +36,7 @@ static void configfs_free_inode(struct inode *inode)
 
 static const struct super_operations configfs_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.free_inode	= configfs_free_inode,
 };
 
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index b002e9b734f9..12daa85ed941 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -116,9 +116,18 @@ static struct inode *get_cramfs_inode(struct super_block *sb,
 		inode_nohighmem(inode);
 		inode->i_data.a_ops = &cramfs_aops;
 		break;
-	default:
+	case S_IFCHR:
+	case S_IFBLK:
+	case S_IFIFO:
+	case S_IFSOCK:
 		init_special_inode(inode, cramfs_inode->mode,
 				old_decode_dev(cramfs_inode->size));
+		break;
+	default:
+		printk(KERN_DEBUG "CRAMFS: Invalid file type 0%04o for inode %lu.\n",
+		       inode->i_mode, inode->i_ino);
+		iget_failed(inode);
+		return ERR_PTR(-EIO);
 	}
 
 	inode->i_mode = cramfs_inode->mode;
diff --git a/fs/dcache.c b/fs/dcache.c
index 60046ae23d51..336bdb4c4b1f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2509,8 +2509,8 @@ static inline unsigned start_dir_add(struct inode *dir)
 {
 	preempt_disable_nested();
 	for (;;) {
-		unsigned n = dir->i_dir_seq;
-		if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
+		unsigned n = READ_ONCE(dir->i_dir_seq);
+		if (!(n & 1) && try_cmpxchg(&dir->i_dir_seq, &n, n + 1))
 			return n;
 		cpu_relax();
 	}
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 4bb4002e3cdf..1f4d8ce56667 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -127,7 +127,7 @@ static int efivarfs_unfreeze_fs(struct super_block *sb);
 
 static const struct super_operations efivarfs_ops = {
 	.statfs = efivarfs_statfs,
-	.drop_inode = generic_delete_inode,
+	.drop_inode = inode_just_drop,
 	.alloc_inode = efivarfs_alloc_inode,
 	.free_inode = efivarfs_free_inode,
 	.show_options = efivarfs_show_options,
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index b22d6f819f78..ee7c4b683ec3 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -46,10 +46,10 @@
  *
  * 1) epnested_mutex (mutex)
  * 2) ep->mtx (mutex)
- * 3) ep->lock (rwlock)
+ * 3) ep->lock (spinlock)
  *
  * The acquire order is the one listed above, from 1 to 3.
- * We need a rwlock (ep->lock) because we manipulate objects
+ * We need a spinlock (ep->lock) because we manipulate objects
  * from inside the poll callback, that might be triggered from
  * a wake_up() that in turn might be called from IRQ context.
  * So we can't sleep inside the poll callback and hence we need
@@ -195,7 +195,7 @@ struct eventpoll {
 	struct list_head rdllist;
 
 	/* Lock which protects rdllist and ovflist */
-	rwlock_t lock;
+	spinlock_t lock;
 
 	/* RB tree root used to store monitored fd structs */
 	struct rb_root_cached rbr;
@@ -741,10 +741,10 @@ static void ep_start_scan(struct eventpoll *ep, struct list_head *txlist)
 	 * in a lockless way.
 	 */
 	lockdep_assert_irqs_enabled();
-	write_lock_irq(&ep->lock);
+	spin_lock_irq(&ep->lock);
 	list_splice_init(&ep->rdllist, txlist);
 	WRITE_ONCE(ep->ovflist, NULL);
-	write_unlock_irq(&ep->lock);
+	spin_unlock_irq(&ep->lock);
 }
 
 static void ep_done_scan(struct eventpoll *ep,
@@ -752,7 +752,7 @@ static void ep_done_scan(struct eventpoll *ep,
 {
 	struct epitem *epi, *nepi;
 
-	write_lock_irq(&ep->lock);
+	spin_lock_irq(&ep->lock);
 	/*
 	 * During the time we spent inside the "sproc" callback, some
 	 * other events might have been queued by the poll callback.
@@ -793,7 +793,7 @@ static void ep_done_scan(struct eventpoll *ep,
 			wake_up(&ep->wq);
 	}
 
-	write_unlock_irq(&ep->lock);
+	spin_unlock_irq(&ep->lock);
 }
 
 static void ep_get(struct eventpoll *ep)
@@ -868,10 +868,10 @@ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force)
 
 	rb_erase_cached(&epi->rbn, &ep->rbr);
 
-	write_lock_irq(&ep->lock);
+	spin_lock_irq(&ep->lock);
 	if (ep_is_linked(epi))
 		list_del_init(&epi->rdllink);
-	write_unlock_irq(&ep->lock);
+	spin_unlock_irq(&ep->lock);
 
 	wakeup_source_unregister(ep_wakeup_source(epi));
 	/*
@@ -1152,7 +1152,7 @@ static int ep_alloc(struct eventpoll **pep)
 		return -ENOMEM;
 
 	mutex_init(&ep->mtx);
-	rwlock_init(&ep->lock);
+	spin_lock_init(&ep->lock);
 	init_waitqueue_head(&ep->wq);
 	init_waitqueue_head(&ep->poll_wait);
 	INIT_LIST_HEAD(&ep->rdllist);
@@ -1240,99 +1240,9 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd,
 #endif /* CONFIG_KCMP */
 
 /*
- * Adds a new entry to the tail of the list in a lockless way, i.e.
- * multiple CPUs are allowed to call this function concurrently.
- *
- * Beware: it is necessary to prevent any other modifications of the
- *         existing list until all changes are completed, in other words
- *         concurrent list_add_tail_lockless() calls should be protected
- *         with a read lock, where write lock acts as a barrier which
- *         makes sure all list_add_tail_lockless() calls are fully
- *         completed.
- *
- *        Also an element can be locklessly added to the list only in one
- *        direction i.e. either to the tail or to the head, otherwise
- *        concurrent access will corrupt the list.
- *
- * Return: %false if element has been already added to the list, %true
- * otherwise.
- */
-static inline bool list_add_tail_lockless(struct list_head *new,
-					  struct list_head *head)
-{
-	struct list_head *prev;
-
-	/*
-	 * This is simple 'new->next = head' operation, but cmpxchg()
-	 * is used in order to detect that same element has been just
-	 * added to the list from another CPU: the winner observes
-	 * new->next == new.
-	 */
-	if (!try_cmpxchg(&new->next, &new, head))
-		return false;
-
-	/*
-	 * Initially ->next of a new element must be updated with the head
-	 * (we are inserting to the tail) and only then pointers are atomically
-	 * exchanged.  XCHG guarantees memory ordering, thus ->next should be
-	 * updated before pointers are actually swapped and pointers are
-	 * swapped before prev->next is updated.
-	 */
-
-	prev = xchg(&head->prev, new);
-
-	/*
-	 * It is safe to modify prev->next and new->prev, because a new element
-	 * is added only to the tail and new->next is updated before XCHG.
-	 */
-
-	prev->next = new;
-	new->prev = prev;
-
-	return true;
-}
-
-/*
- * Chains a new epi entry to the tail of the ep->ovflist in a lockless way,
- * i.e. multiple CPUs are allowed to call this function concurrently.
- *
- * Return: %false if epi element has been already chained, %true otherwise.
- */
-static inline bool chain_epi_lockless(struct epitem *epi)
-{
-	struct eventpoll *ep = epi->ep;
-
-	/* Fast preliminary check */
-	if (epi->next != EP_UNACTIVE_PTR)
-		return false;
-
-	/* Check that the same epi has not been just chained from another CPU */
-	if (cmpxchg(&epi->next, EP_UNACTIVE_PTR, NULL) != EP_UNACTIVE_PTR)
-		return false;
-
-	/* Atomically exchange tail */
-	epi->next = xchg(&ep->ovflist, epi);
-
-	return true;
-}
-
-/*
  * This is the callback that is passed to the wait queue wakeup
  * mechanism. It is called by the stored file descriptors when they
  * have events to report.
- *
- * This callback takes a read lock in order not to contend with concurrent
- * events from another file descriptor, thus all modifications to ->rdllist
- * or ->ovflist are lockless.  Read lock is paired with the write lock from
- * ep_start/done_scan(), which stops all list modifications and guarantees
- * that lists state is seen correctly.
- *
- * Another thing worth to mention is that ep_poll_callback() can be called
- * concurrently for the same @epi from different CPUs if poll table was inited
- * with several wait queues entries.  Plural wakeup from different CPUs of a
- * single wait queue is serialized by wq.lock, but the case when multiple wait
- * queues are used should be detected accordingly.  This is detected using
- * cmpxchg() operation.
  */
 static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 {
@@ -1343,7 +1253,7 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
 	unsigned long flags;
 	int ewake = 0;
 
-	read_lock_irqsave(&ep->lock, flags);
+	spin_lock_irqsave(&ep->lock, flags);
 
 	ep_set_busy_poll_napi_id(epi);
 
@@ -1372,12 +1282,15 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
 	 * chained in ep->ovflist and requeued later on.
 	 */
 	if (READ_ONCE(ep->ovflist) != EP_UNACTIVE_PTR) {
-		if (chain_epi_lockless(epi))
+		if (epi->next == EP_UNACTIVE_PTR) {
+			epi->next = READ_ONCE(ep->ovflist);
+			WRITE_ONCE(ep->ovflist, epi);
 			ep_pm_stay_awake_rcu(epi);
+		}
 	} else if (!ep_is_linked(epi)) {
 		/* In the usual case, add event to ready list. */
-		if (list_add_tail_lockless(&epi->rdllink, &ep->rdllist))
-			ep_pm_stay_awake_rcu(epi);
+		list_add_tail(&epi->rdllink, &ep->rdllist);
+		ep_pm_stay_awake_rcu(epi);
 	}
 
 	/*
@@ -1410,7 +1323,7 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
 		pwake++;
 
 out_unlock:
-	read_unlock_irqrestore(&ep->lock, flags);
+	spin_unlock_irqrestore(&ep->lock, flags);
 
 	/* We have to call this outside the lock */
 	if (pwake)
@@ -1745,7 +1658,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
 	}
 
 	/* We have to drop the new item inside our item list to keep track of it */
-	write_lock_irq(&ep->lock);
+	spin_lock_irq(&ep->lock);
 
 	/* record NAPI ID of new item if present */
 	ep_set_busy_poll_napi_id(epi);
@@ -1762,7 +1675,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
 			pwake++;
 	}
 
-	write_unlock_irq(&ep->lock);
+	spin_unlock_irq(&ep->lock);
 
 	/* We have to call this outside the lock */
 	if (pwake)
@@ -1826,7 +1739,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi,
 	 * list, push it inside.
 	 */
 	if (ep_item_poll(epi, &pt, 1)) {
-		write_lock_irq(&ep->lock);
+		spin_lock_irq(&ep->lock);
 		if (!ep_is_linked(epi)) {
 			list_add_tail(&epi->rdllink, &ep->rdllist);
 			ep_pm_stay_awake(epi);
@@ -1837,7 +1750,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi,
 			if (waitqueue_active(&ep->poll_wait))
 				pwake++;
 		}
-		write_unlock_irq(&ep->lock);
+		spin_unlock_irq(&ep->lock);
 	}
 
 	/* We have to call this outside the lock */
@@ -2089,7 +2002,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 		init_wait(&wait);
 		wait.func = ep_autoremove_wake_function;
 
-		write_lock_irq(&ep->lock);
+		spin_lock_irq(&ep->lock);
 		/*
 		 * Barrierless variant, waitqueue_active() is called under
 		 * the same lock on wakeup ep_poll_callback() side, so it
@@ -2108,7 +2021,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 		if (!eavail)
 			__add_wait_queue_exclusive(&ep->wq, &wait);
 
-		write_unlock_irq(&ep->lock);
+		spin_unlock_irq(&ep->lock);
 
 		if (!eavail)
 			timed_out = !ep_schedule_timeout(to) ||
@@ -2124,7 +2037,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 		eavail = 1;
 
 		if (!list_empty_careful(&wait.entry)) {
-			write_lock_irq(&ep->lock);
+			spin_lock_irq(&ep->lock);
 			/*
 			 * If the thread timed out and is not on the wait queue,
 			 * it means that the thread was woken up after its
@@ -2135,7 +2048,7 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
 			if (timed_out)
 				eavail = list_empty(&wait.entry);
 			__remove_wait_queue(&ep->wq, &wait);
-			write_unlock_irq(&ep->lock);
+			spin_unlock_irq(&ep->lock);
 		}
 	}
 }
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 699c15db28a8..caac4067f777 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1417,7 +1417,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 
 static int ext4_drop_inode(struct inode *inode)
 {
-	int drop = generic_drop_inode(inode);
+	int drop = inode_generic_drop(inode);
 
 	if (!drop)
 		drop = fscrypt_drop_inode(inode);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e16c4e2830c2..63cf73409da6 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1768,7 +1768,7 @@ static int f2fs_drop_inode(struct inode *inode)
 		trace_f2fs_drop_inode(inode, 0);
 		return 0;
 	}
-	ret = generic_drop_inode(inode);
+	ret = inode_generic_drop(inode);
 	if (!ret)
 		ret = fscrypt_drop_inode(inode);
 	trace_f2fs_drop_inode(inode, ret);
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 5598e4d57422..72f8433d9109 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -355,8 +355,7 @@ static bool rw_hint_valid(u64 hint)
 	}
 }
 
-static long fcntl_get_rw_hint(struct file *file, unsigned int cmd,
-			      unsigned long arg)
+static long fcntl_get_rw_hint(struct file *file, unsigned long arg)
 {
 	struct inode *inode = file_inode(file);
 	u64 __user *argp = (u64 __user *)arg;
@@ -367,8 +366,7 @@ static long fcntl_get_rw_hint(struct file *file, unsigned int cmd,
 	return 0;
 }
 
-static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,
-			      unsigned long arg)
+static long fcntl_set_rw_hint(struct file *file, unsigned long arg)
 {
 	struct inode *inode = file_inode(file);
 	u64 __user *argp = (u64 __user *)arg;
@@ -547,10 +545,10 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 		err = memfd_fcntl(filp, cmd, argi);
 		break;
 	case F_GET_RW_HINT:
-		err = fcntl_get_rw_hint(filp, cmd, arg);
+		err = fcntl_get_rw_hint(filp, arg);
 		break;
 	case F_SET_RW_HINT:
-		err = fcntl_set_rw_hint(filp, cmd, arg);
+		err = fcntl_set_rw_hint(filp, arg);
 		break;
 	default:
 		break;
diff --git a/fs/file.c b/fs/file.c
index 6d2275c3be9c..28743b742e3c 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -1330,7 +1330,10 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags)
 	err = expand_files(files, fd);
 	if (unlikely(err < 0))
 		goto out_unlock;
-	return do_dup2(files, file, fd, flags);
+	err = do_dup2(files, file, fd, flags);
+	if (err < 0)
+		return err;
+	return 0;
 
 out_unlock:
 	spin_unlock(&files->file_lock);
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index a07b8cf73ae2..a6cc3d305b84 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1123,7 +1123,7 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
 	dirty = dirty * 10 / 8;
 
 	/* issue the writeback work */
-	work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN);
+	work = kzalloc(sizeof(*work), GFP_NOWAIT);
 	if (work) {
 		work->nr_pages = dirty;
 		work->sync_mode = WB_SYNC_NONE;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7ddfd2b3cc9c..fdecd5a90dee 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1209,7 +1209,7 @@ static const struct super_operations fuse_super_operations = {
 	.free_inode     = fuse_free_inode,
 	.evict_inode	= fuse_evict_inode,
 	.write_inode	= fuse_write_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.umount_begin	= fuse_umount_begin,
 	.statfs		= fuse_statfs,
 	.sync_fs	= fuse_sync_fs,
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index b42e2110084b..644b2d1e7276 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1050,7 +1050,7 @@ static int gfs2_drop_inode(struct inode *inode)
 	if (test_bit(SDF_EVICTING, &sdp->sd_flags))
 		return 1;
 
-	return generic_drop_inode(inode);
+	return inode_generic_drop(inode);
 }
 
 /**
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 01e516175bcd..1e1acf5775ab 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -261,7 +261,7 @@ static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
 static const struct super_operations hostfs_sbops = {
 	.alloc_inode	= hostfs_alloc_inode,
 	.free_inode	= hostfs_free_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= hostfs_evict_inode,
 	.statfs		= hostfs_statfs,
 	.show_options	= hostfs_show_options,
diff --git a/fs/inode.c b/fs/inode.c
index 01ebdc40021e..a66c02123bca 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1838,11 +1838,11 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
 EXPORT_SYMBOL(insert_inode_locked4);
 
 
-int generic_delete_inode(struct inode *inode)
+int inode_just_drop(struct inode *inode)
 {
 	return 1;
 }
-EXPORT_SYMBOL(generic_delete_inode);
+EXPORT_SYMBOL(inode_just_drop);
 
 /*
  * Called when we're dropping the last reference
@@ -1866,7 +1866,7 @@ static void iput_final(struct inode *inode)
 	if (op->drop_inode)
 		drop = op->drop_inode(inode);
 	else
-		drop = generic_drop_inode(inode);
+		drop = inode_generic_drop(inode);
 
 	if (!drop &&
 	    !(inode->i_state & I_DONTCACHE) &&
@@ -2189,7 +2189,7 @@ static int __remove_privs(struct mnt_idmap *idmap,
 	return notify_change(idmap, dentry, &newattrs, NULL);
 }
 
-int file_remove_privs_flags(struct file *file, unsigned int flags)
+static int file_remove_privs_flags(struct file *file, unsigned int flags)
 {
 	struct dentry *dentry = file_dentry(file);
 	struct inode *inode = file_inode(file);
@@ -2214,7 +2214,6 @@ int file_remove_privs_flags(struct file *file, unsigned int flags)
 		inode_has_no_xattr(inode);
 	return error;
 }
-EXPORT_SYMBOL_GPL(file_remove_privs_flags);
 
 /**
  * file_remove_privs - remove special file privileges (suid, capabilities)
@@ -2519,21 +2518,28 @@ void __init inode_init(void)
 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
 {
 	inode->i_mode = mode;
-	if (S_ISCHR(mode)) {
+	switch (inode->i_mode & S_IFMT) {
+	case S_IFCHR:
 		inode->i_fop = &def_chr_fops;
 		inode->i_rdev = rdev;
-	} else if (S_ISBLK(mode)) {
+		break;
+	case S_IFBLK:
 		if (IS_ENABLED(CONFIG_BLOCK))
 			inode->i_fop = &def_blk_fops;
 		inode->i_rdev = rdev;
-	} else if (S_ISFIFO(mode))
+		break;
+	case S_IFIFO:
 		inode->i_fop = &pipefifo_fops;
-	else if (S_ISSOCK(mode))
-		;	/* leave it no_open_fops */
-	else
+		break;
+	case S_IFSOCK:
+		/* leave it no_open_fops */
+		break;
+	default:
 		printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
 				  " inode %s:%lu\n", mode, inode->i_sb->s_id,
 				  inode->i_ino);
+		break;
+	}
 }
 EXPORT_SYMBOL(init_special_inode);
 
@@ -2914,7 +2920,7 @@ EXPORT_SYMBOL(mode_strip_sgid);
  */
 void dump_inode(struct inode *inode, const char *reason)
 {
-       pr_warn("%s encountered for inode %px", reason, inode);
+	pr_warn("%s encountered for inode %px (%s)\n", reason, inode, inode->i_sb->s_type->name);
 }
 
 EXPORT_SYMBOL(dump_inode);
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 0248cb8db2d3..1c152c2b1b67 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -41,7 +41,7 @@
  *
  * Returns 0 on success, -errno on error.
  */
-int vfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+static int vfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	int error = -ENOTTY;
 
@@ -54,7 +54,6 @@ int vfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  out:
 	return error;
 }
-EXPORT_SYMBOL(vfs_ioctl);
 
 static int ioctl_fibmap(struct file *filp, int __user *p)
 {
@@ -426,7 +425,7 @@ static int ioctl_file_dedupe_range(struct file *file,
 		goto out;
 	}
 
-	size = offsetof(struct file_dedupe_range, info[count]);
+	size = struct_size(same, info, count);
 	if (size > PAGE_SIZE) {
 		ret = -ENOMEM;
 		goto out;
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index e384a69fbece..76eaf64b9d9e 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -57,7 +57,7 @@ static int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 
 const struct super_operations kernfs_sops = {
 	.statfs		= kernfs_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= kernfs_evict_inode,
 
 	.show_options	= kernfs_sop_show_options,
diff --git a/fs/locks.c b/fs/locks.c
index 559f02aa4172..04a3f0e20724 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2328,8 +2328,8 @@ out:
  * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
  * locks, the ->lock() interface may return asynchronously, before the lock has
  * been granted or denied by the underlying filesystem, if (and only if)
- * lm_grant is set. Additionally EXPORT_OP_ASYNC_LOCK in export_operations
- * flags need to be set.
+ * lm_grant is set. Additionally FOP_ASYNC_LOCK in file_operations fop_flags
+ * need to be set.
  *
  * Callers expecting ->lock() to return asynchronously will only use F_SETLK,
  * not F_SETLKW; they will set FL_SLEEP if (and only if) the request is for a
diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index df9d11479caf..32db676127a9 100644
--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -492,8 +492,14 @@ void minix_set_inode(struct inode *inode, dev_t rdev)
 		inode->i_op = &minix_symlink_inode_operations;
 		inode_nohighmem(inode);
 		inode->i_mapping->a_ops = &minix_aops;
-	} else
+	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
+		   S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 		init_special_inode(inode, inode->i_mode, rdev);
+	} else {
+		printk(KERN_DEBUG "MINIX-fs: Invalid file type 0%04o for inode %lu.\n",
+		       inode->i_mode, inode->i_ino);
+		make_bad_inode(inode);
+	}
 }
 
 /*
diff --git a/fs/namei.c b/fs/namei.c
index cd43ff89fbaa..44856b70ea3b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1449,6 +1449,10 @@ static int follow_automount(struct path *path, int *count, unsigned lookup_flags
 	    dentry->d_inode)
 		return -EISDIR;
 
+	/* No need to trigger automounts if mountpoint crossing is disabled. */
+	if (lookup_flags & LOOKUP_NO_XDEV)
+		return -EXDEV;
+
 	if (count && (*count)++ >= MAXSYMLINKS)
 		return -ELOOP;
 
@@ -1472,6 +1476,10 @@ static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped,
 		/* Allow the filesystem to manage the transit without i_rwsem
 		 * being held. */
 		if (flags & DCACHE_MANAGE_TRANSIT) {
+			if (lookup_flags & LOOKUP_NO_XDEV) {
+				ret = -EXDEV;
+				break;
+			}
 			ret = path->dentry->d_op->d_manage(path, false);
 			flags = smp_load_acquire(&path->dentry->d_flags);
 			if (ret < 0)
@@ -1489,6 +1497,10 @@ static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped,
 				// here we know it's positive
 				flags = path->dentry->d_flags;
 				need_mntput = true;
+				if (unlikely(lookup_flags & LOOKUP_NO_XDEV)) {
+					ret = -EXDEV;
+					break;
+				}
 				continue;
 			}
 		}
@@ -1630,12 +1642,8 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
 			return -ECHILD;
 	}
 	ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags);
-	if (jumped) {
-		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
-			ret = -EXDEV;
-		else
-			nd->state |= ND_JUMPED;
-	}
+	if (jumped)
+		nd->state |= ND_JUMPED;
 	if (unlikely(ret)) {
 		dput(path->dentry);
 		if (path->mnt != nd->path.mnt)
@@ -4828,7 +4836,7 @@ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
 		return -EPERM;
 	/*
 	 * Updating the link count will likely cause i_uid and i_gid to
-	 * be writen back improperly if their true value is unknown to
+	 * be written back improperly if their true value is unknown to
 	 * the vfs.
 	 */
 	if (HAS_UNMAPPED_ID(idmap, inode))
diff --git a/fs/namespace.c b/fs/namespace.c
index 51f77c65c0c6..38609066cf33 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -65,6 +65,15 @@ static int __init set_mphash_entries(char *str)
 }
 __setup("mphash_entries=", set_mphash_entries);
 
+static char * __initdata initramfs_options;
+static int __init initramfs_options_setup(char *str)
+{
+	initramfs_options = str;
+	return 1;
+}
+
+__setup("initramfs_options=", initramfs_options_setup);
+
 static u64 event;
 static DEFINE_XARRAY_FLAGS(mnt_id_xa, XA_FLAGS_ALLOC);
 static DEFINE_IDA(mnt_group_ida);
@@ -5711,7 +5720,6 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root)
 static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
 			struct mnt_namespace *ns)
 {
-	struct path root __free(path_put) = {};
 	struct mount *m;
 	int err;
 
@@ -5723,7 +5731,7 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
 	if (!s->mnt)
 		return -ENOENT;
 
-	err = grab_requested_root(ns, &root);
+	err = grab_requested_root(ns, &s->root);
 	if (err)
 		return err;
 
@@ -5732,7 +5740,7 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
 	 * mounts to show users.
 	 */
 	m = real_mount(s->mnt);
-	if (!is_path_reachable(m, m->mnt.mnt_root, &root) &&
+	if (!is_path_reachable(m, m->mnt.mnt_root, &s->root) &&
 	    !ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
@@ -5740,8 +5748,6 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
 	if (err)
 		return err;
 
-	s->root = root;
-
 	/*
 	 * Note that mount properties in mnt->mnt_flags, mnt->mnt_idmap
 	 * can change concurrently as we only hold the read-side of the
@@ -5963,28 +5969,40 @@ retry:
 	if (!ret)
 		ret = copy_statmount_to_user(ks);
 	kvfree(ks->seq.buf);
+	path_put(&ks->root);
 	if (retry_statmount(ret, &seq_size))
 		goto retry;
 	return ret;
 }
 
-static ssize_t do_listmount(struct mnt_namespace *ns, u64 mnt_parent_id,
-			    u64 last_mnt_id, u64 *mnt_ids, size_t nr_mnt_ids,
-			    bool reverse)
+struct klistmount {
+	u64 last_mnt_id;
+	u64 mnt_parent_id;
+	u64 *kmnt_ids;
+	u32 nr_mnt_ids;
+	struct mnt_namespace *ns;
+	struct path root;
+};
+
+static ssize_t do_listmount(struct klistmount *kls, bool reverse)
 {
-	struct path root __free(path_put) = {};
+	struct mnt_namespace *ns = kls->ns;
+	u64 mnt_parent_id = kls->mnt_parent_id;
+	u64 last_mnt_id = kls->last_mnt_id;
+	u64 *mnt_ids = kls->kmnt_ids;
+	size_t nr_mnt_ids = kls->nr_mnt_ids;
 	struct path orig;
 	struct mount *r, *first;
 	ssize_t ret;
 
 	rwsem_assert_held(&namespace_sem);
 
-	ret = grab_requested_root(ns, &root);
+	ret = grab_requested_root(ns, &kls->root);
 	if (ret)
 		return ret;
 
 	if (mnt_parent_id == LSMT_ROOT) {
-		orig = root;
+		orig = kls->root;
 	} else {
 		orig.mnt = lookup_mnt_in_ns(mnt_parent_id, ns);
 		if (!orig.mnt)
@@ -5996,7 +6014,7 @@ static ssize_t do_listmount(struct mnt_namespace *ns, u64 mnt_parent_id,
 	 * Don't trigger audit denials. We just want to determine what
 	 * mounts to show users.
 	 */
-	if (!is_path_reachable(real_mount(orig.mnt), orig.dentry, &root) &&
+	if (!is_path_reachable(real_mount(orig.mnt), orig.dentry, &kls->root) &&
 	    !ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
@@ -6029,14 +6047,45 @@ static ssize_t do_listmount(struct mnt_namespace *ns, u64 mnt_parent_id,
 	return ret;
 }
 
+static void __free_klistmount_free(const struct klistmount *kls)
+{
+	path_put(&kls->root);
+	kvfree(kls->kmnt_ids);
+	mnt_ns_release(kls->ns);
+}
+
+static inline int prepare_klistmount(struct klistmount *kls, struct mnt_id_req *kreq,
+				     size_t nr_mnt_ids)
+{
+
+	u64 last_mnt_id = kreq->param;
+
+	/* The first valid unique mount id is MNT_UNIQUE_ID_OFFSET + 1. */
+	if (last_mnt_id != 0 && last_mnt_id <= MNT_UNIQUE_ID_OFFSET)
+		return -EINVAL;
+
+	kls->last_mnt_id = last_mnt_id;
+
+	kls->nr_mnt_ids = nr_mnt_ids;
+	kls->kmnt_ids = kvmalloc_array(nr_mnt_ids, sizeof(*kls->kmnt_ids),
+				       GFP_KERNEL_ACCOUNT);
+	if (!kls->kmnt_ids)
+		return -ENOMEM;
+
+	kls->ns = grab_requested_mnt_ns(kreq);
+	if (!kls->ns)
+		return -ENOENT;
+
+	kls->mnt_parent_id = kreq->mnt_id;
+	return 0;
+}
+
 SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 		u64 __user *, mnt_ids, size_t, nr_mnt_ids, unsigned int, flags)
 {
-	u64 *kmnt_ids __free(kvfree) = NULL;
+	struct klistmount kls __free(klistmount_free) = {};
 	const size_t maxcount = 1000000;
-	struct mnt_namespace *ns __free(mnt_ns_release) = NULL;
 	struct mnt_id_req kreq;
-	u64 last_mnt_id;
 	ssize_t ret;
 
 	if (flags & ~LISTMOUNT_REVERSE)
@@ -6057,22 +6106,12 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 	if (ret)
 		return ret;
 
-	last_mnt_id = kreq.param;
-	/* The first valid unique mount id is MNT_UNIQUE_ID_OFFSET + 1. */
-	if (last_mnt_id != 0 && last_mnt_id <= MNT_UNIQUE_ID_OFFSET)
-		return -EINVAL;
-
-	kmnt_ids = kvmalloc_array(nr_mnt_ids, sizeof(*kmnt_ids),
-				  GFP_KERNEL_ACCOUNT);
-	if (!kmnt_ids)
-		return -ENOMEM;
-
-	ns = grab_requested_mnt_ns(&kreq);
-	if (!ns)
-		return -ENOENT;
+	ret = prepare_klistmount(&kls, &kreq, nr_mnt_ids);
+	if (ret)
+		return ret;
 
-	if (kreq.mnt_ns_id && (ns != current->nsproxy->mnt_ns) &&
-	    !ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
+	if (kreq.mnt_ns_id && (kls.ns != current->nsproxy->mnt_ns) &&
+	    !ns_capable_noaudit(kls.ns->user_ns, CAP_SYS_ADMIN))
 		return -ENOENT;
 
 	/*
@@ -6080,12 +6119,11 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req,
 	 * listmount() doesn't care about any mount properties.
 	 */
 	scoped_guard(rwsem_read, &namespace_sem)
-		ret = do_listmount(ns, kreq.mnt_id, last_mnt_id, kmnt_ids,
-				   nr_mnt_ids, (flags & LISTMOUNT_REVERSE));
+		ret = do_listmount(&kls, (flags & LISTMOUNT_REVERSE));
 	if (ret <= 0)
 		return ret;
 
-	if (copy_to_user(mnt_ids, kmnt_ids, ret * sizeof(*mnt_ids)))
+	if (copy_to_user(mnt_ids, kls.kmnt_ids, ret * sizeof(*mnt_ids)))
 		return -EFAULT;
 
 	return ret;
@@ -6098,7 +6136,7 @@ static void __init init_mount_tree(void)
 	struct mnt_namespace *ns;
 	struct path root;
 
-	mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL);
+	mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", initramfs_options);
 	if (IS_ERR(mnt))
 		panic("Can't create rootfs");
 
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 49df9debb1a6..43f09d8eb5e3 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -108,7 +108,7 @@ u64 nfs_compat_user_ino64(u64 fileid)
 
 int nfs_drop_inode(struct inode *inode)
 {
-	return NFS_STALE(inode) || generic_drop_inode(inode);
+	return NFS_STALE(inode) || inode_generic_drop(inode);
 }
 EXPORT_SYMBOL_GPL(nfs_drop_inode);
 
diff --git a/fs/ocfs2/dlmfs/dlmfs.c b/fs/ocfs2/dlmfs/dlmfs.c
index 5130ec44e5e1..807e2b758a5c 100644
--- a/fs/ocfs2/dlmfs/dlmfs.c
+++ b/fs/ocfs2/dlmfs/dlmfs.c
@@ -547,7 +547,7 @@ static const struct super_operations dlmfs_ops = {
 	.alloc_inode	= dlmfs_alloc_inode,
 	.free_inode	= dlmfs_free_inode,
 	.evict_inode	= dlmfs_evict_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 };
 
 static const struct inode_operations dlmfs_file_inode_operations = {
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index f3da840758e7..b46100a4f529 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -306,7 +306,7 @@ static const struct super_operations orangefs_s_ops = {
 	.free_inode = orangefs_free_inode,
 	.destroy_inode = orangefs_destroy_inode,
 	.write_inode = orangefs_write_inode,
-	.drop_inode = generic_delete_inode,
+	.drop_inode = inode_just_drop,
 	.statfs = orangefs_statfs,
 	.show_options = orangefs_show_options,
 };
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index df85a76597e9..bd3d7ba8fb95 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -280,7 +280,7 @@ static const struct super_operations ovl_super_operations = {
 	.alloc_inode	= ovl_alloc_inode,
 	.free_inode	= ovl_free_inode,
 	.destroy_inode	= ovl_destroy_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.put_super	= ovl_put_super,
 	.sync_fs	= ovl_sync_fs,
 	.statfs		= ovl_statfs,
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 108e7527f837..d01729c5263a 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -718,7 +718,7 @@ static void pidfs_evict_inode(struct inode *inode)
 }
 
 static const struct super_operations pidfs_sops = {
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= pidfs_evict_inode,
 	.statfs		= simple_statfs,
 };
diff --git a/fs/pipe.c b/fs/pipe.c
index 731622d0738d..42fead1efe52 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -458,7 +458,8 @@ anon_pipe_write(struct kiocb *iocb, struct iov_iter *from)
 	mutex_lock(&pipe->mutex);
 
 	if (!pipe->readers) {
-		send_sig(SIGPIPE, current, 0);
+		if ((iocb->ki_flags & IOCB_NOSIGNAL) == 0)
+			send_sig(SIGPIPE, current, 0);
 		ret = -EPIPE;
 		goto out;
 	}
@@ -498,7 +499,8 @@ anon_pipe_write(struct kiocb *iocb, struct iov_iter *from)
 
 	for (;;) {
 		if (!pipe->readers) {
-			send_sig(SIGPIPE, current, 0);
+			if ((iocb->ki_flags & IOCB_NOSIGNAL) == 0)
+				send_sig(SIGPIPE, current, 0);
 			if (!ret)
 				ret = -EPIPE;
 			break;
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 129490151be1..d9b7ef122343 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -187,7 +187,7 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root)
 const struct super_operations proc_sops = {
 	.alloc_inode	= proc_alloc_inode,
 	.free_inode	= proc_free_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= proc_evict_inode,
 	.statfs		= simple_statfs,
 	.show_options	= proc_show_options,
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 4403a2e20c16..ea2b597fd92c 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -12,7 +12,7 @@
 #include "internal.h"
 
 
-static const struct proc_ns_operations *ns_entries[] = {
+static const struct proc_ns_operations *const ns_entries[] = {
 #ifdef CONFIG_NET_NS
 	&netns_operations,
 #endif
@@ -117,7 +117,7 @@ static struct dentry *proc_ns_instantiate(struct dentry *dentry,
 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct task_struct *task = get_proc_task(file_inode(file));
-	const struct proc_ns_operations **entry, **last;
+	const struct proc_ns_operations *const *entry, *const *last;
 
 	if (!task)
 		return -ENOENT;
@@ -151,7 +151,7 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 				struct dentry *dentry, unsigned int flags)
 {
 	struct task_struct *task = get_proc_task(dir);
-	const struct proc_ns_operations **entry, **last;
+	const struct proc_ns_operations *const *entry, *const *last;
 	unsigned int len = dentry->d_name.len;
 	struct dentry *res = ERR_PTR(-ENOENT);
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index ed86ac710384..fd1f1c8a939a 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -38,12 +38,14 @@ enum proc_param {
 	Opt_gid,
 	Opt_hidepid,
 	Opt_subset,
+	Opt_pidns,
 };
 
 static const struct fs_parameter_spec proc_fs_parameters[] = {
-	fsparam_u32("gid",	Opt_gid),
+	fsparam_u32("gid",		Opt_gid),
 	fsparam_string("hidepid",	Opt_hidepid),
 	fsparam_string("subset",	Opt_subset),
+	fsparam_file_or_string("pidns",	Opt_pidns),
 	{}
 };
 
@@ -109,11 +111,66 @@ static int proc_parse_subset_param(struct fs_context *fc, char *value)
 	return 0;
 }
 
+#ifdef CONFIG_PID_NS
+static int proc_parse_pidns_param(struct fs_context *fc,
+				  struct fs_parameter *param,
+				  struct fs_parse_result *result)
+{
+	struct proc_fs_context *ctx = fc->fs_private;
+	struct pid_namespace *target, *active = task_active_pid_ns(current);
+	struct ns_common *ns;
+	struct file *ns_filp __free(fput) = NULL;
+
+	switch (param->type) {
+	case fs_value_is_file:
+		/* came through fsconfig, steal the file reference */
+		ns_filp = no_free_ptr(param->file);
+		break;
+	case fs_value_is_string:
+		ns_filp = filp_open(param->string, O_RDONLY, 0);
+		break;
+	default:
+		WARN_ON_ONCE(true);
+		break;
+	}
+	if (!ns_filp)
+		ns_filp = ERR_PTR(-EBADF);
+	if (IS_ERR(ns_filp)) {
+		errorfc(fc, "could not get file from pidns argument");
+		return PTR_ERR(ns_filp);
+	}
+
+	if (!proc_ns_file(ns_filp))
+		return invalfc(fc, "pidns argument is not an nsfs file");
+	ns = get_proc_ns(file_inode(ns_filp));
+	if (ns->ops->type != CLONE_NEWPID)
+		return invalfc(fc, "pidns argument is not a pidns file");
+	target = container_of(ns, struct pid_namespace, ns);
+
+	/*
+	 * pidns= is shorthand for joining the pidns to get a fsopen fd, so the
+	 * permission model should be the same as pidns_install().
+	 */
+	if (!ns_capable(target->user_ns, CAP_SYS_ADMIN)) {
+		errorfc(fc, "insufficient permissions to set pidns");
+		return -EPERM;
+	}
+	if (!pidns_is_ancestor(target, active))
+		return invalfc(fc, "cannot set pidns to non-descendant pidns");
+
+	put_pid_ns(ctx->pid_ns);
+	ctx->pid_ns = get_pid_ns(target);
+	put_user_ns(fc->user_ns);
+	fc->user_ns = get_user_ns(ctx->pid_ns->user_ns);
+	return 0;
+}
+#endif /* CONFIG_PID_NS */
+
 static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
 	struct proc_fs_context *ctx = fc->fs_private;
 	struct fs_parse_result result;
-	int opt;
+	int opt, err;
 
 	opt = fs_parse(fc, proc_fs_parameters, param, &result);
 	if (opt < 0)
@@ -125,14 +182,38 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		break;
 
 	case Opt_hidepid:
-		if (proc_parse_hidepid_param(fc, param))
-			return -EINVAL;
+		err = proc_parse_hidepid_param(fc, param);
+		if (err)
+			return err;
 		break;
 
 	case Opt_subset:
-		if (proc_parse_subset_param(fc, param->string) < 0)
-			return -EINVAL;
+		err = proc_parse_subset_param(fc, param->string);
+		if (err)
+			return err;
+		break;
+
+	case Opt_pidns:
+#ifdef CONFIG_PID_NS
+		/*
+		 * We would have to RCU-protect every proc_pid_ns() or
+		 * proc_sb_info() access if we allowed this to be reconfigured
+		 * for an existing procfs instance. Luckily, procfs instances
+		 * are cheap to create, and mount-beneath would let you
+		 * atomically replace an instance even with overmounts.
+		 */
+		if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
+			errorfc(fc, "cannot reconfigure pidns for existing procfs");
+			return -EBUSY;
+		}
+		err = proc_parse_pidns_param(fc, param, &result);
+		if (err)
+			return err;
 		break;
+#else
+		errorfc(fc, "pidns mount flag not supported on this system");
+		return -EOPNOTSUPP;
+#endif
 
 	default:
 		return -EINVAL;
@@ -154,6 +235,11 @@ static void proc_apply_options(struct proc_fs_info *fs_info,
 		fs_info->hide_pid = ctx->hidepid;
 	if (ctx->mask & (1 << Opt_subset))
 		fs_info->pidonly = ctx->pidonly;
+	if (ctx->mask & (1 << Opt_pidns) &&
+	    !WARN_ON_ONCE(fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)) {
+		put_pid_ns(fs_info->pid_ns);
+		fs_info->pid_ns = get_pid_ns(ctx->pid_ns);
+	}
 }
 
 static int proc_fill_super(struct super_block *s, struct fs_context *fc)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 1a2e1185426c..b4e55c90f8dc 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -282,7 +282,7 @@ static int pstore_reconfigure(struct fs_context *fc)
 
 static const struct super_operations pstore_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.evict_inode	= pstore_evict_inode,
 	.show_options	= pstore_show_options,
 };
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index f8874c3b8c1e..41f9995da7ca 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -215,7 +215,7 @@ static int ramfs_show_options(struct seq_file *m, struct dentry *root)
 
 static const struct super_operations ramfs_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.show_options	= ramfs_show_options,
 };
 
diff --git a/fs/read_write.c b/fs/read_write.c
index c5b6265d984b..833bae068770 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1576,6 +1576,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	if (len == 0)
 		return 0;
 
+	/*
+	 * Make sure return value doesn't overflow in 32bit compat mode.  Also
+	 * limit the size for all cases except when calling ->copy_file_range().
+	 */
+	if (splice || !file_out->f_op->copy_file_range || in_compat_syscall())
+		len = min_t(size_t, MAX_RW_COUNT, len);
+
 	file_start_write(file_out);
 
 	/*
@@ -1589,9 +1596,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 						      len, flags);
 	} else if (!splice && file_in->f_op->remap_file_range && samesb) {
 		ret = file_in->f_op->remap_file_range(file_in, pos_in,
-				file_out, pos_out,
-				min_t(loff_t, MAX_RW_COUNT, len),
-				REMAP_FILE_CAN_SHORTEN);
+				file_out, pos_out, len, REMAP_FILE_CAN_SHORTEN);
 		/* fallback to splice */
 		if (ret <= 0)
 			splice = true;
@@ -1624,8 +1629,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 	 * to splicing from input file, while file_start_write() is held on
 	 * the output file on a different sb.
 	 */
-	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
-			       min_t(size_t, len, MAX_RW_COUNT), 0);
+	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0);
 done:
 	if (ret > 0) {
 		fsnotify_access(file_in);
diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index e1848276bab4..b0e84ca5d268 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -857,7 +857,7 @@ static int cifs_drop_inode(struct inode *inode)
 
 	/* no serverino => unconditional eviction */
 	return !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) ||
-		generic_drop_inode(inode);
+		inode_generic_drop(inode);
 }
 
 static const struct super_operations cifs_super_ops = {
diff --git a/fs/super.c b/fs/super.c
index 7f876f32343a..e91718017701 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -2318,13 +2318,15 @@ int sb_init_dio_done_wq(struct super_block *sb)
 						      sb->s_id);
 	if (!wq)
 		return -ENOMEM;
+
+	old = NULL;
 	/*
 	 * This has to be atomic as more DIOs can race to create the workqueue
 	 */
-	old = cmpxchg(&sb->s_dio_done_wq, NULL, wq);
-	/* Someone created workqueue before us? Free ours... */
-	if (old)
+	if (!try_cmpxchg(&sb->s_dio_done_wq, &old, wq)) {
+		/* Someone created workqueue before us? Free ours... */
 		destroy_workqueue(wq);
+	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(sb_init_dio_done_wq);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index f3e3b2068608..733fd1e5a9a2 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -335,7 +335,7 @@ static int ubifs_write_inode(struct inode *inode, struct writeback_control *wbc)
 
 static int ubifs_drop_inode(struct inode *inode)
 {
-	int drop = generic_drop_inode(inode);
+	int drop = inode_generic_drop(inode);
 
 	if (!drop)
 		drop = fscrypt_drop_inode(inode);
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index bb0a82635a77..a05ff68748dc 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -778,7 +778,7 @@ xfs_fs_drop_inode(
 		return 0;
 	}
 
-	return generic_drop_inode(inode);
+	return inode_generic_drop(inode);
 }
 
 STATIC void
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 601d036a6c78..e90384db5544 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -357,6 +357,7 @@ struct readahead_control;
 #define IOCB_APPEND		(__force int) RWF_APPEND
 #define IOCB_ATOMIC		(__force int) RWF_ATOMIC
 #define IOCB_DONTCACHE		(__force int) RWF_DONTCACHE
+#define IOCB_NOSIGNAL		(__force int) RWF_NOSIGNAL
 
 /* non-RWF related bits - start at 16 */
 #define IOCB_EVENTFD		(1 << 16)
@@ -2053,8 +2054,6 @@ int vfs_fchown(struct file *file, uid_t user, gid_t group);
 int vfs_fchmod(struct file *file, umode_t mode);
 int vfs_utimes(const struct path *path, struct timespec64 *times);
 
-int vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
-
 #ifdef CONFIG_COMPAT
 extern long compat_ptr_ioctl(struct file *file, unsigned int cmd,
 					unsigned long arg);
@@ -3282,7 +3281,7 @@ static inline bool is_dot_dotdot(const char *name, size_t len)
 
 /**
  * name_contains_dotdot - check if a file name contains ".." path components
- *
+ * @name: File path string to check
  * Search for ".." surrounded by either '/' or start/end of string.
  */
 static inline bool name_contains_dotdot(const char *name)
@@ -3314,8 +3313,8 @@ extern void address_space_init_once(struct address_space *mapping);
 extern struct inode * igrab(struct inode *);
 extern ino_t iunique(struct super_block *, ino_t);
 extern int inode_needs_sync(struct inode *inode);
-extern int generic_delete_inode(struct inode *inode);
-static inline int generic_drop_inode(struct inode *inode)
+extern int inode_just_drop(struct inode *inode);
+static inline int inode_generic_drop(struct inode *inode)
 {
 	return !inode->i_nlink || inode_unhashed(inode);
 }
@@ -3394,7 +3393,6 @@ static inline struct inode *new_inode_pseudo(struct super_block *sb)
 extern struct inode *new_inode(struct super_block *sb);
 extern void free_inode_nonrcu(struct inode *inode);
 extern int setattr_should_drop_suidgid(struct mnt_idmap *, struct inode *);
-extern int file_remove_privs_flags(struct file *file, unsigned int flags);
 extern int file_remove_privs(struct file *);
 int setattr_should_drop_sgid(struct mnt_idmap *idmap,
 			     const struct inode *inode);
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 7c67a5811199..17fdc059f8da 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -84,6 +84,9 @@ extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
 extern int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd);
 extern void put_pid_ns(struct pid_namespace *ns);
 
+extern bool pidns_is_ancestor(struct pid_namespace *child,
+			      struct pid_namespace *ancestor);
+
 #else /* !CONFIG_PID_NS */
 #include <linux/err.h>
 
@@ -118,6 +121,12 @@ static inline int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
 {
 	return 0;
 }
+
+static inline bool pidns_is_ancestor(struct pid_namespace *child,
+				     struct pid_namespace *ancestor)
+{
+	return false;
+}
 #endif /* CONFIG_PID_NS */
 
 extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk);
diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h
index b8d1e00a7982..2dfeb158e848 100644
--- a/include/trace/events/filelock.h
+++ b/include/trace/events/filelock.h
@@ -27,7 +27,8 @@
 		{ FL_SLEEP,		"FL_SLEEP" },			\
 		{ FL_DOWNGRADE_PENDING,	"FL_DOWNGRADE_PENDING" },	\
 		{ FL_UNLOCK_PENDING,	"FL_UNLOCK_PENDING" },		\
-		{ FL_OFDLCK,		"FL_OFDLCK" })
+		{ FL_OFDLCK,		"FL_OFDLCK" },			\
+		{ FL_RECLAIM,		"FL_RECLAIM"})
 
 #define show_fl_type(val)				\
 	__print_symbolic(val,				\
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 0bd678a4a10e..beb4c2d1e41c 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -430,10 +430,13 @@ typedef int __bitwise __kernel_rwf_t;
 /* buffered IO that drops the cache after reading or writing data */
 #define RWF_DONTCACHE	((__force __kernel_rwf_t)0x00000080)
 
+/* prevent pipe and socket writes from raising SIGPIPE */
+#define RWF_NOSIGNAL	((__force __kernel_rwf_t)0x00000100)
+
 /* mask of flags supported by the kernel */
 #define RWF_SUPPORTED	(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\
 			 RWF_APPEND | RWF_NOAPPEND | RWF_ATOMIC |\
-			 RWF_DONTCACHE)
+			 RWF_DONTCACHE | RWF_NOSIGNAL)
 
 #define PROCFS_IOCTL_MAGIC 'f'
 
diff --git a/init/Kconfig b/init/Kconfig
index 6a91ec742186..87c868f86a06 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1504,6 +1504,7 @@ config BOOT_CONFIG_EMBED_FILE
 
 config INITRAMFS_PRESERVE_MTIME
 	bool "Preserve cpio archive mtimes in initramfs"
+	depends on BLK_DEV_INITRD
 	default y
 	help
 	  Each entry in an initramfs cpio archive carries an mtime value. When
diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index ac021ae6e6fa..19d9f33dcacf 100644
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -7,6 +7,7 @@
 #include <uapi/linux/cramfs_fs.h>
 #include <linux/initrd.h>
 #include <linux/string.h>
+#include <linux/string_choices.h>
 #include <linux/slab.h>
 
 #include "do_mounts.h"
@@ -186,14 +187,12 @@ static unsigned long nr_blocks(struct file *file)
 int __init rd_load_image(char *from)
 {
 	int res = 0;
-	unsigned long rd_blocks, devblocks;
+	unsigned long rd_blocks, devblocks, nr_disks;
 	int nblocks, i;
 	char *buf = NULL;
 	unsigned short rotate = 0;
 	decompress_fn decompressor = NULL;
-#if !defined(CONFIG_S390)
 	char rotator[4] = { '|' , '/' , '-' , '\\' };
-#endif
 
 	out_file = filp_open("/dev/ram", O_RDWR, 0);
 	if (IS_ERR(out_file))
@@ -244,8 +243,9 @@ int __init rd_load_image(char *from)
 		goto done;
 	}
 
-	printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
-		nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
+	nr_disks = (nblocks - 1) / devblocks + 1;
+	pr_notice("RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
+		  nblocks, nr_disks, str_plural(nr_disks));
 	for (i = 0; i < nblocks; i++) {
 		if (i && (i % devblocks == 0)) {
 			pr_cont("done disk #1.\n");
@@ -255,12 +255,10 @@ int __init rd_load_image(char *from)
 		}
 		kernel_read(in_file, buf, BLOCK_SIZE, &in_pos);
 		kernel_write(out_file, buf, BLOCK_SIZE, &out_pos);
-#if !defined(CONFIG_S390)
-		if (!(i % 16)) {
+		if (!IS_ENABLED(CONFIG_S390) && !(i % 16)) {
 			pr_cont("%c\b", rotator[rotate & 0x3]);
 			rotate++;
 		}
-#endif
 	}
 	pr_cont("done.\n");
 
diff --git a/init/initramfs.c b/init/initramfs.c
index 097673b97784..6ddbfb17fb8f 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -19,6 +19,7 @@
 #include <linux/init_syscalls.h>
 #include <linux/umh.h>
 #include <linux/security.h>
+#include <linux/overflow.h>
 
 #include "do_mounts.h"
 #include "initramfs_internal.h"
@@ -108,7 +109,7 @@ static char __init *find_link(int major, int minor, int ino,
 	q->minor = minor;
 	q->ino = ino;
 	q->mode = mode;
-	strcpy(q->name, name);
+	strscpy(q->name, name);
 	q->next = NULL;
 	*p = q;
 	hardlink_seen = true;
@@ -152,7 +153,7 @@ static void __init dir_add(const char *name, size_t nlen, time64_t mtime)
 {
 	struct dir_entry *de;
 
-	de = kmalloc(sizeof(struct dir_entry) + nlen, GFP_KERNEL);
+	de = kmalloc(struct_size(de, name, nlen), GFP_KERNEL);
 	if (!de)
 		panic_show_mem("can't allocate dir_entry buffer");
 	INIT_LIST_HEAD(&de->list);
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 5c2e96b19392..6d021d18afa6 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -788,7 +788,7 @@ static void bpf_free_inode(struct inode *inode)
 
 const struct super_operations bpf_super_ops = {
 	.statfs		= simple_statfs,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.show_options	= bpf_show_options,
 	.free_inode	= bpf_free_inode,
 };
diff --git a/kernel/pid.c b/kernel/pid.c
index c45a28c16cd2..d94ce0250501 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -680,7 +680,7 @@ static int pid_table_root_permissions(struct ctl_table_header *head,
 		container_of(head->set, struct pid_namespace, set);
 	int mode = table->mode;
 
-	if (ns_capable(pidns->user_ns, CAP_SYS_ADMIN) ||
+	if (ns_capable_noaudit(pidns->user_ns, CAP_SYS_ADMIN) ||
 	    uid_eq(current_euid(), make_kuid(pidns->user_ns, 0)))
 		mode = (mode & S_IRWXU) >> 6;
 	else if (in_egroup_p(make_kgid(pidns->user_ns, 0)))
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 7098ed44e717..b7b45c2597ec 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -390,11 +390,23 @@ static void pidns_put(struct ns_common *ns)
 	put_pid_ns(to_pid_ns(ns));
 }
 
+bool pidns_is_ancestor(struct pid_namespace *child,
+		       struct pid_namespace *ancestor)
+{
+	struct pid_namespace *ns;
+
+	if (child->level < ancestor->level)
+		return false;
+	for (ns = child; ns->level > ancestor->level; ns = ns->parent)
+		;
+	return ns == ancestor;
+}
+
 static int pidns_install(struct nsset *nsset, struct ns_common *ns)
 {
 	struct nsproxy *nsproxy = nsset->nsproxy;
 	struct pid_namespace *active = task_active_pid_ns(current);
-	struct pid_namespace *ancestor, *new = to_pid_ns(ns);
+	struct pid_namespace *new = to_pid_ns(ns);
 
 	if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
 	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
@@ -408,13 +420,7 @@ static int pidns_install(struct nsset *nsset, struct ns_common *ns)
 	 * this maintains the property that processes and their
 	 * children can not escape their current pid namespace.
 	 */
-	if (new->level < active->level)
-		return -EINVAL;
-
-	ancestor = new;
-	while (ancestor->level > active->level)
-		ancestor = ancestor->parent;
-	if (ancestor != active)
+	if (!pidns_is_ancestor(new, active))
 		return -EINVAL;
 
 	put_pid_ns(nsproxy->pid_ns_for_children);
diff --git a/mm/shmem.c b/mm/shmem.c
index e2c76a30802b..932727247c64 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5341,7 +5341,7 @@ static const struct super_operations shmem_ops = {
 	.get_dquots	= shmem_get_dquots,
 #endif
 	.evict_inode	= shmem_evict_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= inode_just_drop,
 	.put_super	= shmem_put_super,
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	.nr_cached_objects	= shmem_unused_huge_count,
diff --git a/net/socket.c b/net/socket.c
index 682969deaed3..bac335ecee4c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1176,6 +1176,9 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (sock->type == SOCK_SEQPACKET)
 		msg.msg_flags |= MSG_EOR;
 
+	if (iocb->ki_flags & IOCB_NOSIGNAL)
+		msg.msg_flags |= MSG_NOSIGNAL;
+
 	res = __sock_sendmsg(sock, &msg);
 	*from = msg.msg_iter;
 	return res;
diff --git a/tools/testing/selftests/proc/.gitignore b/tools/testing/selftests/proc/.gitignore
index 19bb333e2485..6b78a8382d40 100644
--- a/tools/testing/selftests/proc/.gitignore
+++ b/tools/testing/selftests/proc/.gitignore
@@ -18,6 +18,7 @@
 /proc-tid0
 /proc-uptime-001
 /proc-uptime-002
+/proc-pidns
 /read
 /self
 /setns-dcache
diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile
index 50aba102201a..be3013515aae 100644
--- a/tools/testing/selftests/proc/Makefile
+++ b/tools/testing/selftests/proc/Makefile
@@ -28,5 +28,6 @@ TEST_GEN_PROGS += setns-sysvipc
 TEST_GEN_PROGS += thread-self
 TEST_GEN_PROGS += proc-multiple-procfs
 TEST_GEN_PROGS += proc-fsconfig-hidepid
+TEST_GEN_PROGS += proc-pidns
 
 include ../lib.mk
diff --git a/tools/testing/selftests/proc/proc-pidns.c b/tools/testing/selftests/proc/proc-pidns.c
new file mode 100644
index 000000000000..52500597f951
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-pidns.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Aleksa Sarai <cyphar@cyphar.com>
+ * Copyright (C) 2025 SUSE LLC.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/prctl.h>
+
+#include "../kselftest_harness.h"
+
+#define ASSERT_ERRNO(expected, _t, seen)				\
+	__EXPECT(expected, #expected,					\
+		({__typeof__(seen) _tmp_seen = (seen);			\
+		  _tmp_seen >= 0 ? _tmp_seen : -errno; }), #seen, _t, 1)
+
+#define ASSERT_ERRNO_EQ(expected, seen) \
+	ASSERT_ERRNO(expected, ==, seen)
+
+#define ASSERT_SUCCESS(seen) \
+	ASSERT_ERRNO(0, <=, seen)
+
+static int touch(char *path)
+{
+	int fd = open(path, O_WRONLY|O_CREAT|O_CLOEXEC, 0644);
+	if (fd < 0)
+		return -1;
+	return close(fd);
+}
+
+FIXTURE(ns)
+{
+	int host_mntns, host_pidns;
+	int dummy_pidns;
+};
+
+FIXTURE_SETUP(ns)
+{
+	/* Stash the old mntns. */
+	self->host_mntns = open("/proc/self/ns/mnt", O_RDONLY|O_CLOEXEC);
+	ASSERT_SUCCESS(self->host_mntns);
+
+	/* Create a new mount namespace and make it private. */
+	ASSERT_SUCCESS(unshare(CLONE_NEWNS));
+	ASSERT_SUCCESS(mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL));
+
+	/*
+	 * Create a proper tmpfs that we can use and will disappear once we
+	 * leave this mntns.
+	 */
+	ASSERT_SUCCESS(mount("tmpfs", "/tmp", "tmpfs", 0, NULL));
+
+	/*
+	 * Create a pidns we can use for later tests. We need to fork off a
+	 * child so that we get a usable nsfd that we can bind-mount and open.
+	 */
+	ASSERT_SUCCESS(mkdir("/tmp/dummy", 0755));
+	ASSERT_SUCCESS(touch("/tmp/dummy/pidns"));
+	ASSERT_SUCCESS(mkdir("/tmp/dummy/proc", 0755));
+
+	self->host_pidns = open("/proc/self/ns/pid", O_RDONLY|O_CLOEXEC);
+	ASSERT_SUCCESS(self->host_pidns);
+	ASSERT_SUCCESS(unshare(CLONE_NEWPID));
+
+	pid_t pid = fork();
+	ASSERT_SUCCESS(pid);
+	if (!pid) {
+		prctl(PR_SET_PDEATHSIG, SIGKILL);
+		ASSERT_SUCCESS(mount("/proc/self/ns/pid", "/tmp/dummy/pidns", NULL, MS_BIND, NULL));
+		ASSERT_SUCCESS(mount("proc", "/tmp/dummy/proc", "proc", 0, NULL));
+		exit(0);
+	}
+
+	int wstatus;
+	ASSERT_EQ(waitpid(pid, &wstatus, 0), pid);
+	ASSERT_TRUE(WIFEXITED(wstatus));
+	ASSERT_EQ(WEXITSTATUS(wstatus), 0);
+
+	ASSERT_SUCCESS(setns(self->host_pidns, CLONE_NEWPID));
+
+	self->dummy_pidns = open("/tmp/dummy/pidns", O_RDONLY|O_CLOEXEC);
+	ASSERT_SUCCESS(self->dummy_pidns);
+}
+
+FIXTURE_TEARDOWN(ns)
+{
+	ASSERT_SUCCESS(setns(self->host_mntns, CLONE_NEWNS));
+	ASSERT_SUCCESS(close(self->host_mntns));
+
+	ASSERT_SUCCESS(close(self->host_pidns));
+	ASSERT_SUCCESS(close(self->dummy_pidns));
+}
+
+TEST_F(ns, pidns_mount_string_path)
+{
+	ASSERT_SUCCESS(mkdir("/tmp/proc-host", 0755));
+	ASSERT_SUCCESS(mount("proc", "/tmp/proc-host", "proc", 0, "pidns=/proc/self/ns/pid"));
+	ASSERT_SUCCESS(access("/tmp/proc-host/self/", X_OK));
+
+	ASSERT_SUCCESS(mkdir("/tmp/proc-dummy", 0755));
+	ASSERT_SUCCESS(mount("proc", "/tmp/proc-dummy", "proc", 0, "pidns=/tmp/dummy/pidns"));
+	ASSERT_ERRNO_EQ(-ENOENT, access("/tmp/proc-dummy/1/", X_OK));
+	ASSERT_ERRNO_EQ(-ENOENT, access("/tmp/proc-dummy/self/", X_OK));
+}
+
+TEST_F(ns, pidns_fsconfig_string_path)
+{
+	int fsfd = fsopen("proc", FSOPEN_CLOEXEC);
+	ASSERT_SUCCESS(fsfd);
+
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_SET_STRING, "pidns", "/tmp/dummy/pidns", 0));
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0));
+
+	int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0);
+	ASSERT_SUCCESS(mountfd);
+
+	ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_SUCCESS(close(fsfd));
+	ASSERT_SUCCESS(close(mountfd));
+}
+
+TEST_F(ns, pidns_fsconfig_fd)
+{
+	int fsfd = fsopen("proc", FSOPEN_CLOEXEC);
+	ASSERT_SUCCESS(fsfd);
+
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_SET_FD, "pidns", NULL, self->dummy_pidns));
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0));
+
+	int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0);
+	ASSERT_SUCCESS(mountfd);
+
+	ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_ERRNO_EQ(-ENOENT, faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_SUCCESS(close(fsfd));
+	ASSERT_SUCCESS(close(mountfd));
+}
+
+TEST_F(ns, pidns_reconfigure_remount)
+{
+	ASSERT_SUCCESS(mkdir("/tmp/proc", 0755));
+	ASSERT_SUCCESS(mount("proc", "/tmp/proc", "proc", 0, ""));
+
+	ASSERT_SUCCESS(access("/tmp/proc/1/", X_OK));
+	ASSERT_SUCCESS(access("/tmp/proc/self/", X_OK));
+
+	ASSERT_ERRNO_EQ(-EBUSY, mount(NULL, "/tmp/proc", NULL, MS_REMOUNT, "pidns=/tmp/dummy/pidns"));
+
+	ASSERT_SUCCESS(access("/tmp/proc/1/", X_OK));
+	ASSERT_SUCCESS(access("/tmp/proc/self/", X_OK));
+}
+
+TEST_F(ns, pidns_reconfigure_fsconfig_string_path)
+{
+	int fsfd = fsopen("proc", FSOPEN_CLOEXEC);
+	ASSERT_SUCCESS(fsfd);
+
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0));
+
+	int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0);
+	ASSERT_SUCCESS(mountfd);
+
+	ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_ERRNO_EQ(-EBUSY, fsconfig(fsfd, FSCONFIG_SET_STRING, "pidns", "/tmp/dummy/pidns", 0));
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0)); /* noop */
+
+	ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_SUCCESS(close(fsfd));
+	ASSERT_SUCCESS(close(mountfd));
+}
+
+TEST_F(ns, pidns_reconfigure_fsconfig_fd)
+{
+	int fsfd = fsopen("proc", FSOPEN_CLOEXEC);
+	ASSERT_SUCCESS(fsfd);
+
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0));
+
+	int mountfd = fsmount(fsfd, FSMOUNT_CLOEXEC, 0);
+	ASSERT_SUCCESS(mountfd);
+
+	ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_ERRNO_EQ(-EBUSY, fsconfig(fsfd, FSCONFIG_SET_FD, "pidns", NULL, self->dummy_pidns));
+	ASSERT_SUCCESS(fsconfig(fsfd, FSCONFIG_CMD_RECONFIGURE, NULL, NULL, 0)); /* noop */
+
+	ASSERT_SUCCESS(faccessat(mountfd, "1/", X_OK, 0));
+	ASSERT_SUCCESS(faccessat(mountfd, "self/", X_OK, 0));
+
+	ASSERT_SUCCESS(close(fsfd));
+	ASSERT_SUCCESS(close(mountfd));
+}
+
+TEST_HARNESS_MAIN