Merge tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linuxgrafted

Pull io_uring fixes from Jens Axboe:

 - Fix a task_work add use-after-free with SQPOLL.

   The sqpoll thread could pop and complete the last request while
   io_req_normal_work_add() was still looking at them after the mpscq
   push.

   Use the same approach as DEFER_TASKRUN to protect from that, holding
   an RCU read lock across the add, and have exit wait for an RCU grace
   period for SQPOLL rings as well.

 - CQE32 ring fixes: correct the free entry check for 32b CQEs, zero the
   big_cqe for aux CQEs, and only post the dummy skip CQE on CQE_MIXED
   rings

 - Mark the source filter table as COW when cloning bpf filters, so
   registering another filter on the source doesn't modify the shared
   table in place

 - Initialize the task context before running the BPF loop

 - Requeue zcrx multishot receives stopped by a local resource

 - End a TX_TIMESTAMP multishot cmd when the CQ is full (lollipopkit)

* tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  io_uring: fix task_work add use-after-free with SQPOLL
  io_uring/cmd_net: end TX_TIMESTAMP multishot when the CQ is full
  io_uring/zcrx: requeue multishot receives stopped by a local resource
  io_uring: initialize task context before running the BPF loop
  io_uring: zero big_cqe for aux CQEs on CQE32 rings
  io_uring: fix free entry check for 32b CQEs on CQE32 rings
  io_uring: only post the dummy skip CQE on CQE_MIXED rings
  io_uring/bpf_filter: mark source as COW when cloning filters

1 files changed, 687 insertions, 0 deletions

diff --git a/fs/pnode.c b/fs/pnode.c
new file mode 100644
index 000000000..5d91c3e58
--- /dev/null
+++ b/fs/pnode.c
@@ -0,0 +1,687 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/pnode.c
+ *
+ * (C) Copyright IBM Corporation 2005.
+ *	Author : Ram Pai (linuxram@us.ibm.com)
+ */
+#include <linux/mnt_namespace.h>
+#include <linux/mount.h>
+#include <linux/fs.h>
+#include <linux/nsproxy.h>
+#include <uapi/linux/mount.h>
+#include "internal.h"
+#include "pnode.h"
+
+/* return the next shared peer mount of @p */
+static inline struct mount *next_peer(struct mount *p)
+{
+	return list_entry(p->mnt_share.next, struct mount, mnt_share);
+}
+
+static inline struct mount *first_slave(struct mount *p)
+{
+	return hlist_entry(p->mnt_slave_list.first, struct mount, mnt_slave);
+}
+
+static inline struct mount *next_slave(struct mount *p)
+{
+	return hlist_entry(p->mnt_slave.next, struct mount, mnt_slave);
+}
+
+/* locks: namespace_shared && is_mounted(mnt) */
+static struct mount *get_peer_under_root(struct mount *mnt,
+					 struct mnt_namespace *ns,
+					 const struct path *root)
+{
+	struct mount *m = mnt;
+
+	do {
+		/* Check the namespace first for optimization */
+		if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root))
+			return m;
+
+		m = next_peer(m);
+	} while (m != mnt);
+
+	return NULL;
+}
+
+/*
+ * Get ID of closest dominating peer group having a representative
+ * under the given root.
+ *
+ * locks: namespace_shared
+ */
+int get_dominating_id(struct mount *mnt, const struct path *root)
+{
+	struct mount *m;
+
+	for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
+		struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root);
+		if (d)
+			return d->mnt_group_id;
+	}
+
+	return 0;
+}
+
+static inline bool will_be_unmounted(struct mount *m)
+{
+	return m->mnt.mnt_flags & MNT_UMOUNT;
+}
+
+static void transfer_propagation(struct mount *mnt, struct mount *to)
+{
+	struct hlist_node *p = NULL, *n;
+	struct mount *m;
+
+	hlist_for_each_entry_safe(m, n, &mnt->mnt_slave_list, mnt_slave) {
+		m->mnt_master = to;
+		if (!to)
+			hlist_del_init(&m->mnt_slave);
+		else
+			p = &m->mnt_slave;
+	}
+	if (p)
+		hlist_splice_init(&mnt->mnt_slave_list, p, &to->mnt_slave_list);
+}
+
+/*
+ * EXCL[namespace_sem]
+ */
+void change_mnt_propagation(struct mount *mnt, int type)
+{
+	struct mount *m = mnt->mnt_master;
+
+	if (type == MS_SHARED) {
+		set_mnt_shared(mnt);
+		return;
+	}
+	if (IS_MNT_SHARED(mnt)) {
+		if (list_empty(&mnt->mnt_share)) {
+			mnt_release_group_id(mnt);
+		} else {
+			m = next_peer(mnt);
+			list_del_init(&mnt->mnt_share);
+			mnt->mnt_group_id = 0;
+		}
+		CLEAR_MNT_SHARED(mnt);
+		transfer_propagation(mnt, m);
+	}
+	hlist_del_init(&mnt->mnt_slave);
+	if (type == MS_SLAVE) {
+		mnt->mnt_master = m;
+		if (m)
+			hlist_add_head(&mnt->mnt_slave, &m->mnt_slave_list);
+	} else {
+		mnt->mnt_master = NULL;
+		if (type == MS_UNBINDABLE)
+			mnt->mnt_t_flags |= T_UNBINDABLE;
+		else
+			mnt->mnt_t_flags &= ~T_UNBINDABLE;
+	}
+}
+
+static struct mount *trace_transfers(struct mount *m)
+{
+	while (1) {
+		struct mount *next = next_peer(m);
+
+		if (next != m) {
+			list_del_init(&m->mnt_share);
+			m->mnt_group_id = 0;
+			m->mnt_master = next;
+		} else {
+			if (IS_MNT_SHARED(m))
+				mnt_release_group_id(m);
+			next = m->mnt_master;
+		}
+		hlist_del_init(&m->mnt_slave);
+		CLEAR_MNT_SHARED(m);
+		SET_MNT_MARK(m);
+
+		if (!next || !will_be_unmounted(next))
+			return next;
+		if (IS_MNT_MARKED(next))
+			return next->mnt_master;
+		m = next;
+	}
+}
+
+static void set_destinations(struct mount *m, struct mount *master)
+{
+	struct mount *next;
+
+	while ((next = m->mnt_master) != master) {
+		m->mnt_master = master;
+		m = next;
+	}
+}
+
+void bulk_make_private(struct list_head *set)
+{
+	struct mount *m;
+
+	list_for_each_entry(m, set, mnt_list)
+		if (!IS_MNT_MARKED(m))
+			set_destinations(m, trace_transfers(m));
+
+	list_for_each_entry(m, set, mnt_list) {
+		transfer_propagation(m, m->mnt_master);
+		m->mnt_master = NULL;
+		CLEAR_MNT_MARK(m);
+	}
+}
+
+static struct mount *__propagation_next(struct mount *m,
+					 struct mount *origin)
+{
+	while (1) {
+		struct mount *master = m->mnt_master;
+
+		if (master == origin->mnt_master) {
+			struct mount *next = next_peer(m);
+			return (next == origin) ? NULL : next;
+		} else if (m->mnt_slave.next)
+			return next_slave(m);
+
+		/* back at master */
+		m = master;
+	}
+}
+
+/*
+ * get the next mount in the propagation tree.
+ * @m: the mount seen last
+ * @origin: the original mount from where the tree walk initiated
+ *
+ * Note that peer groups form contiguous segments of slave lists.
+ * We rely on that in get_source() to be able to find out if
+ * vfsmount found while iterating with propagation_next() is
+ * a peer of one we'd found earlier.
+ */
+static struct mount *propagation_next(struct mount *m,
+					 struct mount *origin)
+{
+	/* are there any slaves of this mount? */
+	if (!IS_MNT_NEW(m) && !hlist_empty(&m->mnt_slave_list))
+		return first_slave(m);
+
+	return __propagation_next(m, origin);
+}
+
+static struct mount *skip_propagation_subtree(struct mount *m,
+						struct mount *origin)
+{
+	/*
+	 * Advance m past everything that gets propagation from it.
+	 */
+	struct mount *p = __propagation_next(m, origin);
+
+	while (p && peers(m, p))
+		p = __propagation_next(p, origin);
+
+	return p;
+}
+
+static struct mount *next_group(struct mount *m, struct mount *origin)
+{
+	while (1) {
+		while (1) {
+			struct mount *next;
+			if (!IS_MNT_NEW(m) && !hlist_empty(&m->mnt_slave_list))
+				return first_slave(m);
+			next = next_peer(m);
+			if (m->mnt_group_id == origin->mnt_group_id) {
+				if (next == origin)
+					return NULL;
+			} else if (m->mnt_slave.next != &next->mnt_slave)
+				break;
+			m = next;
+		}
+		/* m is the last peer */
+		while (1) {
+			struct mount *master = m->mnt_master;
+			if (m->mnt_slave.next)
+				return next_slave(m);
+			m = next_peer(master);
+			if (master->mnt_group_id == origin->mnt_group_id)
+				break;
+			if (master->mnt_slave.next == &m->mnt_slave)
+				break;
+			m = master;
+		}
+		if (m == origin)
+			return NULL;
+	}
+}
+
+static bool need_secondary(struct mount *m, struct mountpoint *dest_mp)
+{
+	/* skip ones added by this propagate_mnt() */
+	if (IS_MNT_NEW(m))
+		return false;
+	/* skip if mountpoint isn't visible in m */
+	if (!is_subdir(dest_mp->m_dentry, m->mnt.mnt_root))
+		return false;
+	/* skip if m is in the anon_ns */
+	if (is_anon_ns(m->mnt_ns))
+		return false;
+	return true;
+}
+
+static struct mount *find_master(struct mount *m,
+				struct mount *last_copy,
+				struct mount *original)
+{
+	struct mount *p;
+
+	// ascend until there's a copy for something with the same master
+	for (;;) {
+		p = m->mnt_master;
+		if (!p || IS_MNT_MARKED(p))
+			break;
+		m = p;
+	}
+	while (!peers(last_copy, original)) {
+		struct mount *parent = last_copy->mnt_parent;
+		if (parent->mnt_master == p) {
+			if (!peers(parent, m))
+				last_copy = last_copy->mnt_master;
+			break;
+		}
+		last_copy = last_copy->mnt_master;
+	}
+	return last_copy;
+}
+
+/**
+ * propagate_mnt() - create secondary copies for tree attachment
+ * @dest_mnt:    destination mount.
+ * @dest_mp:     destination mountpoint.
+ * @source_mnt:  source mount.
+ * @tree_list:   list of secondaries to be attached.
+ *
+ * Create secondary copies for attaching a tree with root @source_mnt
+ * at mount @dest_mnt with mountpoint @dest_mp.  Link all new mounts
+ * into a propagation graph.  Set mountpoints for all secondaries,
+ * link their roots into @tree_list via ->mnt_hash.
+ */
+int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
+		  struct mount *source_mnt, struct hlist_head *tree_list)
+{
+	struct mount *m, *n, *copy, *this;
+	int err = 0, type;
+
+	if (dest_mnt->mnt_master)
+		SET_MNT_MARK(dest_mnt->mnt_master);
+
+	/* iterate over peer groups, depth first */
+	for (m = dest_mnt; m && !err; m = next_group(m, dest_mnt)) {
+		if (m == dest_mnt) { // have one for dest_mnt itself
+			copy = source_mnt;
+			type = CL_MAKE_SHARED;
+			n = next_peer(m);
+			if (n == m)
+				continue;
+		} else {
+			type = CL_SLAVE;
+			/* beginning of peer group among the slaves? */
+			if (IS_MNT_SHARED(m))
+				type |= CL_MAKE_SHARED;
+			n = m;
+		}
+		do {
+			if (!need_secondary(n, dest_mp))
+				continue;
+			if (type & CL_SLAVE) // first in this peer group
+				copy = find_master(n, copy, source_mnt);
+			this = copy_tree(copy, copy->mnt.mnt_root, type);
+			if (IS_ERR(this)) {
+				err = PTR_ERR(this);
+				break;
+			}
+			scoped_guard(mount_locked_reader)
+				mnt_set_mountpoint(n, dest_mp, this);
+			if (n->mnt_master)
+				SET_MNT_MARK(n->mnt_master);
+			copy = this;
+			hlist_add_head(&this->mnt_hash, tree_list);
+			err = count_mounts(n->mnt_ns, this);
+			if (err)
+				break;
+			type = CL_MAKE_SHARED;
+		} while ((n = next_peer(n)) != m);
+	}
+
+	hlist_for_each_entry(n, tree_list, mnt_hash) {
+		m = n->mnt_parent;
+		if (m->mnt_master)
+			CLEAR_MNT_MARK(m->mnt_master);
+	}
+	if (dest_mnt->mnt_master)
+		CLEAR_MNT_MARK(dest_mnt->mnt_master);
+	return err;
+}
+
+/*
+ * return true if the refcount is greater than count
+ */
+static inline int do_refcount_check(struct mount *mnt, int count)
+{
+	return mnt_get_count(mnt) > count;
+}
+
+/**
+ * propagation_would_overmount - check whether propagation from @from
+ *                               would overmount @to
+ * @from: shared mount
+ * @to:   mount to check
+ * @mp:   future mountpoint of @to on @from
+ *
+ * If @from propagates mounts to @to, @from and @to must either be peers
+ * or one of the masters in the hierarchy of masters of @to must be a
+ * peer of @from.
+ *
+ * If the root of the @to mount is equal to the future mountpoint @mp of
+ * the @to mount on @from then @to will be overmounted by whatever is
+ * propagated to it.
+ *
+ * Context: This function expects namespace_lock() to be held and that
+ *          @mp is stable.
+ * Return: If @from overmounts @to, true is returned, false if not.
+ */
+bool propagation_would_overmount(const struct mount *from,
+				 const struct mount *to,
+				 const struct mountpoint *mp)
+{
+	if (!IS_MNT_SHARED(from))
+		return false;
+
+	if (to->mnt.mnt_root != mp->m_dentry)
+		return false;
+
+	for (const struct mount *m = to; m; m = m->mnt_master) {
+		if (peers(from, m))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * check if the mount 'mnt' can be unmounted successfully.
+ * @mnt: the mount to be checked for unmount
+ * NOTE: unmounting 'mnt' would naturally propagate to all
+ * other mounts its parent propagates to.
+ * Check if any of these mounts that **do not have submounts**
+ * have more references than 'refcnt'. If so return busy.
+ *
+ * vfsmount lock must be held for write
+ */
+int propagate_mount_busy(struct mount *mnt, int refcnt)
+{
+	struct mount *parent = mnt->mnt_parent;
+
+	/*
+	 * quickly check if the current mount can be unmounted.
+	 * If not, we don't have to go checking for all other
+	 * mounts
+	 */
+	if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
+		return 1;
+
+	if (mnt == parent)
+		return 0;
+
+	for (struct mount *m = propagation_next(parent, parent); m;
+	     		m = propagation_next(m, parent)) {
+		struct list_head *head;
+		struct mount *child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
+
+		if (!child)
+			continue;
+
+		head = &child->mnt_mounts;
+		if (!list_empty(head)) {
+			/*
+			 * a mount that covers child completely wouldn't prevent
+			 * it being pulled out; any other would.
+			 */
+			if (!list_is_singular(head) || !child->overmount)
+				continue;
+		}
+		if (do_refcount_check(child, 1))
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Clear MNT_LOCKED when it can be shown to be safe.
+ *
+ * mount_lock lock must be held for write
+ */
+void propagate_mount_unlock(struct mount *mnt)
+{
+	struct mount *parent = mnt->mnt_parent;
+	struct mount *m, *child;
+
+	BUG_ON(parent == mnt);
+
+	for (m = propagation_next(parent, parent); m;
+			m = propagation_next(m, parent)) {
+		child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
+		if (child)
+			child->mnt.mnt_flags &= ~MNT_LOCKED;
+	}
+}
+
+static inline bool is_candidate(struct mount *m)
+{
+	return m->mnt_t_flags & T_UMOUNT_CANDIDATE;
+}
+
+static void umount_one(struct mount *m, struct list_head *to_umount)
+{
+	m->mnt.mnt_flags |= MNT_UMOUNT;
+	list_del_init(&m->mnt_child);
+	move_from_ns(m);
+	list_add_tail(&m->mnt_list, to_umount);
+}
+
+static void remove_from_candidate_list(struct mount *m)
+{
+	m->mnt_t_flags &= ~(T_MARKED | T_UMOUNT_CANDIDATE);
+	list_del_init(&m->mnt_list);
+}
+
+static void gather_candidates(struct list_head *set,
+			      struct list_head *candidates)
+{
+	struct mount *m, *p, *q;
+
+	list_for_each_entry(m, set, mnt_list) {
+		if (is_candidate(m))
+			continue;
+		m->mnt_t_flags |= T_UMOUNT_CANDIDATE;
+		p = m->mnt_parent;
+		q = propagation_next(p, p);
+		while (q) {
+			struct mount *child = __lookup_mnt(&q->mnt,
+							   m->mnt_mountpoint);
+			if (child) {
+				/*
+				 * We might've already run into this one.  That
+				 * must've happened on earlier iteration of the
+				 * outer loop; in that case we can skip those
+				 * parents that get propagation from q - there
+				 * will be nothing new on those as well.
+				 */
+				if (is_candidate(child)) {
+					q = skip_propagation_subtree(q, p);
+					continue;
+				}
+				child->mnt_t_flags |= T_UMOUNT_CANDIDATE;
+				if (!will_be_unmounted(child))
+					list_add(&child->mnt_list, candidates);
+			}
+			q = propagation_next(q, p);
+		}
+	}
+	list_for_each_entry(m, set, mnt_list)
+		m->mnt_t_flags &= ~T_UMOUNT_CANDIDATE;
+}
+
+/*
+ * We know that some child of @m can't be unmounted.  In all places where the
+ * chain of descent of @m has child not overmounting the root of parent,
+ * the parent can't be unmounted either.
+ */
+static void trim_ancestors(struct mount *m)
+{
+	struct mount *p;
+
+	for (p = m->mnt_parent; is_candidate(p); m = p, p = p->mnt_parent) {
+		if (IS_MNT_MARKED(m))	// all candidates beneath are overmounts
+			return;
+		SET_MNT_MARK(m);
+		if (m != p->overmount)
+			p->mnt_t_flags &= ~T_UMOUNT_CANDIDATE;
+	}
+}
+
+/*
+ * Find and exclude all umount candidates forbidden by @m
+ * (see Documentation/filesystems/propagate_umount.txt)
+ * If we can immediately tell that @m is OK to unmount (unlocked
+ * and all children are already committed to unmounting) commit
+ * to unmounting it.
+ * Only @m itself might be taken from the candidates list;
+ * anything found by trim_ancestors() is marked non-candidate
+ * and left on the list.
+ */
+static void trim_one(struct mount *m, struct list_head *to_umount)
+{
+	bool remove_this = false, found = false, umount_this = false;
+	struct mount *n;
+
+	if (!is_candidate(m)) { // trim_ancestors() left it on list
+		remove_from_candidate_list(m);
+		return;
+	}
+
+	list_for_each_entry(n, &m->mnt_mounts, mnt_child) {
+		if (!is_candidate(n)) {
+			found = true;
+			if (n != m->overmount) {
+				remove_this = true;
+				break;
+			}
+		}
+	}
+	if (found) {
+		trim_ancestors(m);
+	} else if (!IS_MNT_LOCKED(m) && list_empty(&m->mnt_mounts)) {
+		remove_this = true;
+		umount_this = true;
+	}
+	if (remove_this) {
+		remove_from_candidate_list(m);
+		if (umount_this)
+			umount_one(m, to_umount);
+	}
+}
+
+static void handle_locked(struct mount *m, struct list_head *to_umount)
+{
+	struct mount *cutoff = m, *p;
+
+	if (!is_candidate(m)) { // trim_ancestors() left it on list
+		remove_from_candidate_list(m);
+		return;
+	}
+	for (p = m; is_candidate(p); p = p->mnt_parent) {
+		remove_from_candidate_list(p);
+		if (!IS_MNT_LOCKED(p))
+			cutoff = p->mnt_parent;
+	}
+	if (will_be_unmounted(p))
+		cutoff = p;
+	while (m != cutoff) {
+		umount_one(m, to_umount);
+		m = m->mnt_parent;
+	}
+}
+
+/*
+ * @m is not to going away, and it overmounts the top of a stack of mounts
+ * that are going away.  We know that all of those are fully overmounted
+ * by the one above (@m being the topmost of the chain), so @m can be slid
+ * in place where the bottom of the stack is attached.
+ *
+ * NOTE: here we temporarily violate a constraint - two mounts end up with
+ * the same parent and mountpoint; that will be remedied as soon as we
+ * return from propagate_umount() - its caller (umount_tree()) will detach
+ * the stack from the parent it (and now @m) is attached to.  umount_tree()
+ * might choose to keep unmounted pieces stuck to each other, but it always
+ * detaches them from the mounts that remain in the tree.
+ */
+static void reparent(struct mount *m)
+{
+	struct mount *p = m;
+	struct mountpoint *mp;
+
+	do {
+		mp = p->mnt_mp;
+		p = p->mnt_parent;
+	} while (will_be_unmounted(p));
+
+	mnt_change_mountpoint(p, mp, m);
+	mnt_notify_add(m);
+}
+
+/**
+ * propagate_umount - apply propagation rules to the set of mounts for umount()
+ * @set: the list of mounts to be unmounted.
+ *
+ * Collect all mounts that receive propagation from the mount in @set and have
+ * no obstacles to being unmounted.  Add these additional mounts to the set.
+ *
+ * See Documentation/filesystems/propagate_umount.txt if you do anything in
+ * this area.
+ *
+ * Locks held:
+ * mount_lock (write_seqlock), namespace_sem (exclusive).
+ */
+void propagate_umount(struct list_head *set)
+{
+	struct mount *m, *p;
+	LIST_HEAD(to_umount);	// committed to unmounting
+	LIST_HEAD(candidates);	// undecided umount candidates
+
+	// collect all candidates
+	gather_candidates(set, &candidates);
+
+	// reduce the set until it's non-shifting
+	list_for_each_entry_safe(m, p, &candidates, mnt_list)
+		trim_one(m, &to_umount);
+
+	// ... and non-revealing
+	while (!list_empty(&candidates)) {
+		m = list_first_entry(&candidates,struct mount, mnt_list);
+		handle_locked(m, &to_umount);
+	}
+
+	// now to_umount consists of all acceptable candidates
+	// deal with reparenting of surviving overmounts on those
+	list_for_each_entry(m, &to_umount, mnt_list) {
+		struct mount *over = m->overmount;
+		if (over && !will_be_unmounted(over))
+			reparent(over);
+	}
+
+	// and fold them into the set
+	list_splice_tail_init(&to_umount, set);
+}