Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

1 files changed, 161 insertions, 0 deletions

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
new file mode 100644
index 000000000..31fb50e16
--- /dev/null
+++ b/fs/fuse/acl.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FUSE: Filesystem in Userspace
+ * Copyright (C) 2016 Canonical Ltd. <seth.forshee@canonical.com>
+ */
+
+#include "fuse_i.h"
+
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+
+static struct posix_acl *__fuse_get_acl(struct fuse_conn *fc,
+					struct inode *inode, int type, bool rcu)
+{
+	int size;
+	const char *name;
+	void *value = NULL;
+	struct posix_acl *acl;
+
+	if (rcu)
+		return ERR_PTR(-ECHILD);
+
+	if (fuse_is_bad(inode))
+		return ERR_PTR(-EIO);
+
+	if (fc->no_getxattr)
+		return NULL;
+
+	if (type == ACL_TYPE_ACCESS)
+		name = XATTR_NAME_POSIX_ACL_ACCESS;
+	else if (type == ACL_TYPE_DEFAULT)
+		name = XATTR_NAME_POSIX_ACL_DEFAULT;
+	else
+		return ERR_PTR(-EOPNOTSUPP);
+
+	value = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!value)
+		return ERR_PTR(-ENOMEM);
+	size = fuse_getxattr(inode, name, value, PAGE_SIZE);
+	if (size > 0)
+		acl = posix_acl_from_xattr(fc->user_ns, value, size);
+	else if ((size == 0) || (size == -ENODATA) ||
+		 (size == -EOPNOTSUPP && fc->no_getxattr))
+		acl = NULL;
+	else if (size == -ERANGE)
+		acl = ERR_PTR(-E2BIG);
+	else
+		acl = ERR_PTR(size);
+
+	kfree(value);
+	return acl;
+}
+
+static inline bool fuse_no_acl(const struct fuse_conn *fc,
+			       const struct inode *inode)
+{
+	/*
+	 * Refuse interacting with POSIX ACLs for daemons that
+	 * don't support FUSE_POSIX_ACL and are not mounted on
+	 * the host to retain backwards compatibility.
+	 */
+	return !fc->posix_acl && (i_user_ns(inode) != &init_user_ns);
+}
+
+struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
+			       struct dentry *dentry, int type)
+{
+	struct inode *inode = d_inode(dentry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	if (fuse_no_acl(fc, inode))
+		return ERR_PTR(-EOPNOTSUPP);
+
+	return __fuse_get_acl(fc, inode, type, false);
+}
+
+struct posix_acl *fuse_get_inode_acl(struct inode *inode, int type, bool rcu)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	/*
+	 * FUSE daemons before FUSE_POSIX_ACL was introduced could get and set
+	 * POSIX ACLs without them being used for permission checking by the
+	 * vfs. Retain that behavior for backwards compatibility as there are
+	 * filesystems that do all permission checking for acls in the daemon
+	 * and not in the kernel.
+	 */
+	if (!fc->posix_acl)
+		return NULL;
+	return __fuse_get_acl(fc,  inode, type, rcu);
+}
+
+int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+		 struct posix_acl *acl, int type)
+{
+	struct inode *inode = d_inode(dentry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	const char *name;
+	int ret;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (fc->no_setxattr || fuse_no_acl(fc, inode))
+		return -EOPNOTSUPP;
+
+	if (type == ACL_TYPE_ACCESS)
+		name = XATTR_NAME_POSIX_ACL_ACCESS;
+	else if (type == ACL_TYPE_DEFAULT)
+		name = XATTR_NAME_POSIX_ACL_DEFAULT;
+	else
+		return -EINVAL;
+
+	if (acl) {
+		unsigned int extra_flags = 0;
+		/*
+		 * Fuse userspace is responsible for updating access
+		 * permissions in the inode, if needed. fuse_setxattr
+		 * invalidates the inode attributes, which will force
+		 * them to be refreshed the next time they are used,
+		 * and it also updates i_ctime.
+		 */
+		size_t size;
+		void *value;
+
+		value = posix_acl_to_xattr(fc->user_ns, acl, &size, GFP_KERNEL);
+		if (!value)
+			return -ENOMEM;
+
+		if (size > PAGE_SIZE) {
+			kfree(value);
+			return -E2BIG;
+		}
+
+		/*
+		 * Fuse daemons without FUSE_POSIX_ACL never changed the passed
+		 * through POSIX ACLs. Such daemons don't expect setgid bits to
+		 * be stripped.
+		 */
+		if (fc->posix_acl &&
+		    !in_group_or_capable(idmap, inode,
+					 i_gid_into_vfsgid(idmap, inode)))
+			extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
+
+		ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
+		kfree(value);
+	} else {
+		ret = fuse_removexattr(inode, name);
+	}
+
+	if (fc->posix_acl) {
+		/*
+		 * Fuse daemons without FUSE_POSIX_ACL never cached POSIX ACLs
+		 * and didn't invalidate attributes. Retain that behavior.
+		 */
+		forget_all_cached_acls(inode);
+		fuse_invalidate_attr(inode);
+	}
+
+	return ret;
+}