Merge tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:
 "As usual, lots of singleton and doubleton patches all over the tree
  and there's little I can say which isn't in the individual changelogs.

  The lengthier patch series are

   - 'kdump: use generic functions to simplify crashkernel reservation
     in arch', from Baoquan He. This is mainly cleanups and
     consolidation of the 'crashkernel=' kernel parameter handling

   - After much discussion, David Laight's 'minmax: Relax type checks in
     min() and max()' is here. Hopefully reduces some typecasting and
     the use of min_t() and max_t()

   - A group of patches from Oleg Nesterov which clean up and slightly
     fix our handling of reads from /proc/PID/task/... and which remove
     task_struct.thread_group"

* tag 'mm-nonmm-stable-2023-11-02-14-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (64 commits)
  scripts/gdb/vmalloc: disable on no-MMU
  scripts/gdb: fix usage of MOD_TEXT not defined when CONFIG_MODULES=n
  .mailmap: add address mapping for Tomeu Vizoso
  mailmap: update email address for Claudiu Beznea
  tools/testing/selftests/mm/run_vmtests.sh: lower the ptrace permissions
  .mailmap: map Benjamin Poirier's address
  scripts/gdb: add lx_current support for riscv
  ocfs2: fix a spelling typo in comment
  proc: test ProtectionKey in proc-empty-vm test
  proc: fix proc-empty-vm test with vsyscall
  fs/proc/base.c: remove unneeded semicolon
  do_io_accounting: use sig->stats_lock
  do_io_accounting: use __for_each_thread()
  ocfs2: replace BUG_ON() at ocfs2_num_free_extents() with ocfs2_error()
  ocfs2: fix a typo in a comment
  scripts/show_delta: add __main__ judgement before main code
  treewide: mark stuff as __ro_after_init
  fs: ocfs2: check status values
  proc: test /proc/${pid}/statm
  compiler.h: move __is_constexpr() to compiler.h
  ...

28 files changed, 110 insertions, 95 deletions

diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index 24192a7667ed..d26222b7eefe 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -24,8 +24,8 @@
 
 #include <linux/uaccess.h>
 
-static struct vfsmount *anon_inode_mnt __read_mostly;
-static struct inode *anon_inode_inode;
+static struct vfsmount *anon_inode_mnt __ro_after_init;
+static struct inode *anon_inode_inode __ro_after_init;
 
 /*
  * anon_inodefs_dname() is called from d_path().
diff --git a/fs/buffer.c b/fs/buffer.c
index 657a62bab73d..967f34b70aa8 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2983,13 +2983,13 @@ EXPORT_SYMBOL(try_to_free_buffers);
 /*
  * Buffer-head allocation
  */
-static struct kmem_cache *bh_cachep __read_mostly;
+static struct kmem_cache *bh_cachep __ro_after_init;
 
 /*
  * Once the number of bh's in the machine exceeds this level, we start
  * stripping them in writeback.
  */
-static unsigned long max_buffer_heads;
+static unsigned long max_buffer_heads __ro_after_init;
 
 int buffer_heads_over_limit;
 
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 6ba032442b39..57cc096c498a 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -25,7 +25,7 @@
 
 #include "internal.h"
 
-static struct kobj_map *cdev_map;
+static struct kobj_map *cdev_map __ro_after_init;
 
 static DEFINE_MUTEX(chrdevs_lock);
 
diff --git a/fs/dcache.c b/fs/dcache.c
index 796e23761ba0..c82ae731df9a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -78,7 +78,7 @@ __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
 
 EXPORT_SYMBOL(rename_lock);
 
-static struct kmem_cache *dentry_cache __read_mostly;
+static struct kmem_cache *dentry_cache __ro_after_init;
 
 const struct qstr empty_name = QSTR_INIT("", 0);
 EXPORT_SYMBOL(empty_name);
@@ -96,9 +96,9 @@ EXPORT_SYMBOL(dotdot_name);
  * information, yet avoid using a prime hash-size or similar.
  */
 
-static unsigned int d_hash_shift __read_mostly;
+static unsigned int d_hash_shift __ro_after_init;
 
-static struct hlist_bl_head *dentry_hashtable __read_mostly;
+static struct hlist_bl_head *dentry_hashtable __ro_after_init;
 
 static inline struct hlist_bl_head *d_hash(unsigned int hash)
 {
@@ -3332,7 +3332,7 @@ static void __init dcache_init(void)
 }
 
 /* SLAB cache for __getname() consumers */
-struct kmem_cache *names_cachep __read_mostly;
+struct kmem_cache *names_cachep __ro_after_init;
 EXPORT_SYMBOL(names_cachep);
 
 void __init vfs_caches_init_early(void)
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 7bc494ee56b9..20533266ade6 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -151,7 +151,7 @@ struct dio {
 	};
 } ____cacheline_aligned_in_smp;
 
-static struct kmem_cache *dio_cache __read_mostly;
+static struct kmem_cache *dio_cache __ro_after_init;
 
 /*
  * How many pages are in the queue?
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1d9a71a0c4c1..2877cc01cff1 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -256,10 +256,10 @@ static u64 loop_check_gen = 0;
 static struct eventpoll *inserting_into;
 
 /* Slab cache used to allocate "struct epitem" */
-static struct kmem_cache *epi_cache __read_mostly;
+static struct kmem_cache *epi_cache __ro_after_init;
 
 /* Slab cache used to allocate "struct eppoll_entry" */
-static struct kmem_cache *pwq_cache __read_mostly;
+static struct kmem_cache *pwq_cache __ro_after_init;
 
 /*
  * List of files with newly added links, where we may need to limit the number
@@ -271,7 +271,7 @@ struct epitems_head {
 };
 static struct epitems_head *tfile_check_list = EP_UNACTIVE_PTR;
 
-static struct kmem_cache *ephead_cache __read_mostly;
+static struct kmem_cache *ephead_cache __ro_after_init;
 
 static inline void free_ephead(struct epitems_head *head)
 {
diff --git a/fs/fcntl.c b/fs/fcntl.c
index e871009f6c88..c80a6acad742 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -844,7 +844,7 @@ int send_sigurg(struct fown_struct *fown)
 }
 
 static DEFINE_SPINLOCK(fasync_lock);
-static struct kmem_cache *fasync_cache __read_mostly;
+static struct kmem_cache *fasync_cache __ro_after_init;
 
 static void fasync_free_rcu(struct rcu_head *head)
 {
diff --git a/fs/file_table.c b/fs/file_table.c
index fa92743ba6a9..de4a2915bfd4 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -40,7 +40,7 @@ static struct files_stat_struct files_stat = {
 };
 
 /* SLAB cache for file structures */
-static struct kmem_cache *filp_cachep __read_mostly;
+static struct kmem_cache *filp_cachep __ro_after_init;
 
 static struct percpu_counter nr_files __cacheline_aligned_in_smp;
 
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 33ca04733e93..ecf789b7168c 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1126,8 +1126,7 @@ static int init_threads(struct gfs2_sbd *sdp)
 	return 0;
 
 fail:
-	kthread_stop(sdp->sd_logd_process);
-	put_task_struct(sdp->sd_logd_process);
+	kthread_stop_put(sdp->sd_logd_process);
 	sdp->sd_logd_process = NULL;
 	return error;
 }
@@ -1135,13 +1134,11 @@ fail:
 void gfs2_destroy_threads(struct gfs2_sbd *sdp)
 {
 	if (sdp->sd_logd_process) {
-		kthread_stop(sdp->sd_logd_process);
-		put_task_struct(sdp->sd_logd_process);
+		kthread_stop_put(sdp->sd_logd_process);
 		sdp->sd_logd_process = NULL;
 	}
 	if (sdp->sd_quotad_process) {
-		kthread_stop(sdp->sd_quotad_process);
-		put_task_struct(sdp->sd_quotad_process);
+		kthread_stop_put(sdp->sd_quotad_process);
 		sdp->sd_quotad_process = NULL;
 	}
 }
diff --git a/fs/inode.c b/fs/inode.c
index 4f8984b97df0..edcd8a61975f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -54,9 +54,9 @@
  *   inode_hash_lock
  */
 
-static unsigned int i_hash_mask __read_mostly;
-static unsigned int i_hash_shift __read_mostly;
-static struct hlist_head *inode_hashtable __read_mostly;
+static unsigned int i_hash_mask __ro_after_init;
+static unsigned int i_hash_shift __ro_after_init;
+static struct hlist_head *inode_hashtable __ro_after_init;
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
 
 /*
@@ -70,7 +70,7 @@ EXPORT_SYMBOL(empty_aops);
 static DEFINE_PER_CPU(unsigned long, nr_inodes);
 static DEFINE_PER_CPU(unsigned long, nr_unused);
 
-static struct kmem_cache *inode_cachep __read_mostly;
+static struct kmem_cache *inode_cachep __ro_after_init;
 
 static long get_nr_inodes(void)
 {
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 79b96e74a8a0..4628edde2e7e 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -21,8 +21,9 @@
 
 #include "kernfs-internal.h"
 
-struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
-struct kernfs_global_locks *kernfs_locks;
+struct kmem_cache *kernfs_node_cache __ro_after_init;
+struct kmem_cache *kernfs_iattrs_cache __ro_after_init;
+struct kernfs_global_locks *kernfs_locks __ro_after_init;
 
 static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
 {
diff --git a/fs/locks.c b/fs/locks.c
index d4e49a990a8d..46d88b9e222c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -167,8 +167,8 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
  */
 static DEFINE_SPINLOCK(blocked_lock_lock);
 
-static struct kmem_cache *flctx_cache __read_mostly;
-static struct kmem_cache *filelock_cache __read_mostly;
+static struct kmem_cache *flctx_cache __ro_after_init;
+static struct kmem_cache *filelock_cache __ro_after_init;
 
 static struct file_lock_context *
 locks_get_lock_context(struct inode *inode, int type)
diff --git a/fs/namespace.c b/fs/namespace.c
index 6bde71735efa..fbf0e596fcd3 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -39,10 +39,10 @@
 /* Maximum number of mounts in a mount namespace */
 static unsigned int sysctl_mount_max __read_mostly = 100000;
 
-static unsigned int m_hash_mask __read_mostly;
-static unsigned int m_hash_shift __read_mostly;
-static unsigned int mp_hash_mask __read_mostly;
-static unsigned int mp_hash_shift __read_mostly;
+static unsigned int m_hash_mask __ro_after_init;
+static unsigned int m_hash_shift __ro_after_init;
+static unsigned int mp_hash_mask __ro_after_init;
+static unsigned int mp_hash_shift __ro_after_init;
 
 static __initdata unsigned long mhash_entries;
 static int __init set_mhash_entries(char *str)
@@ -68,9 +68,9 @@ static u64 event;
 static DEFINE_IDA(mnt_id_ida);
 static DEFINE_IDA(mnt_group_ida);
 
-static struct hlist_head *mount_hashtable __read_mostly;
-static struct hlist_head *mountpoint_hashtable __read_mostly;
-static struct kmem_cache *mnt_cache __read_mostly;
+static struct hlist_head *mount_hashtable __ro_after_init;
+static struct hlist_head *mountpoint_hashtable __ro_after_init;
+static struct kmem_cache *mnt_cache __ro_after_init;
 static DECLARE_RWSEM(namespace_sem);
 static HLIST_HEAD(unmounted);	/* protected by namespace_sem */
 static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */
@@ -86,7 +86,7 @@ struct mount_kattr {
 };
 
 /* /sys/fs */
-struct kobject *fs_kobj;
+struct kobject *fs_kobj __ro_after_init;
 EXPORT_SYMBOL_GPL(fs_kobj);
 
 /*
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 869b016014d2..1cb9ad7e884e 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -39,9 +39,9 @@ static void __init dnotify_sysctl_init(void)
 #define dnotify_sysctl_init() do { } while (0)
 #endif
 
-static struct kmem_cache *dnotify_struct_cache __read_mostly;
-static struct kmem_cache *dnotify_mark_cache __read_mostly;
-static struct fsnotify_group *dnotify_group __read_mostly;
+static struct kmem_cache *dnotify_struct_cache __ro_after_init;
+static struct kmem_cache *dnotify_mark_cache __ro_after_init;
+static struct fsnotify_group *dnotify_group __ro_after_init;
 
 /*
  * dnotify will attach one of these to each inode (i_fsnotify_marks) which
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 62fe0b679e58..45aecdc302f4 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -112,10 +112,10 @@ static void __init fanotify_sysctls_init(void)
 
 extern const struct fsnotify_ops fanotify_fsnotify_ops;
 
-struct kmem_cache *fanotify_mark_cache __read_mostly;
-struct kmem_cache *fanotify_fid_event_cachep __read_mostly;
-struct kmem_cache *fanotify_path_event_cachep __read_mostly;
-struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
+struct kmem_cache *fanotify_mark_cache __ro_after_init;
+struct kmem_cache *fanotify_fid_event_cachep __ro_after_init;
+struct kmem_cache *fanotify_path_event_cachep __ro_after_init;
+struct kmem_cache *fanotify_perm_event_cachep __ro_after_init;
 
 #define FANOTIFY_EVENT_ALIGN 4
 #define FANOTIFY_FID_INFO_HDR_LEN \
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 1c4bfdab008d..a3809ae92170 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -49,7 +49,7 @@
 /* configurable via /proc/sys/fs/inotify/ */
 static int inotify_max_queued_events __read_mostly;
 
-struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
+struct kmem_cache *inotify_inode_mark_cachep __ro_after_init;
 
 #ifdef CONFIG_SYSCTL
 
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index f0937902f7b4..91b32b2377ac 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -967,7 +967,14 @@ int ocfs2_num_free_extents(struct ocfs2_extent_tree *et)
 		el = &eb->h_list;
 	}
 
-	BUG_ON(el->l_tree_depth != 0);
+	if (el->l_tree_depth != 0) {
+		retval = ocfs2_error(ocfs2_metadata_cache_get_super(et->et_ci),
+				"Owner %llu has leaf extent block %llu with an invalid l_tree_depth of %u\n",
+				(unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
+				(unsigned long long)last_eb_blk,
+				le16_to_cpu(el->l_tree_depth));
+		goto bail;
+	}
 
 	retval = le16_to_cpu(el->l_count) - le16_to_cpu(el->l_next_free_rec);
 bail:
@@ -7642,7 +7649,7 @@ out_mutex:
 		goto next_group;
 	}
 out:
-	range->len = trimmed * sb->s_blocksize;
+	range->len = trimmed * osb->s_clustersize;
 	return ret;
 }
 
diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c
index 196638a22b48..cdb9b9bdea1f 100644
--- a/fs/ocfs2/buffer_head_io.c
+++ b/fs/ocfs2/buffer_head_io.c
@@ -158,7 +158,7 @@ read_failure:
 			if (new_bh && bh) {
 				/* If middle bh fails, let previous bh
 				 * finish its read and then put it to
-				 * aovoid bh leak
+				 * avoid bh leak
 				 */
 				if (!buffer_jbd(bh))
 					wait_on_buffer(bh);
@@ -345,7 +345,7 @@ read_failure:
 				if (new_bh && bh) {
 					/* If middle bh fails, let previous bh
 					 * finish its read and then put it to
-					 * aovoid bh leak
+					 * avoid bh leak
 					 */
 					if (!buffer_jbd(bh))
 						wait_on_buffer(bh);
diff --git a/fs/ocfs2/dlmfs/dlmfs.c b/fs/ocfs2/dlmfs/dlmfs.c
index 9b57d012fd5c..85215162c9dd 100644
--- a/fs/ocfs2/dlmfs/dlmfs.c
+++ b/fs/ocfs2/dlmfs/dlmfs.c
@@ -80,8 +80,7 @@ static int param_set_dlmfs_capabilities(const char *val,
 static int param_get_dlmfs_capabilities(char *buffer,
 					const struct kernel_param *kp)
 {
-	return strlcpy(buffer, DLMFS_CAPABILITIES,
-		       strlen(DLMFS_CAPABILITIES) + 1);
+	return sysfs_emit(buffer, DLMFS_CAPABILITIES);
 }
 module_param_call(capabilities, param_set_dlmfs_capabilities,
 		  param_get_dlmfs_capabilities, NULL, 0444);
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index ce215565d061..604fea3a26ff 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -90,7 +90,7 @@ enum ocfs2_replay_state {
 struct ocfs2_replay_map {
 	unsigned int rm_slots;
 	enum ocfs2_replay_state rm_state;
-	unsigned char rm_replay_slots[];
+	unsigned char rm_replay_slots[] __counted_by(rm_slots);
 };
 
 static void ocfs2_replay_map_set_state(struct ocfs2_super *osb, int state)
diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 681e9501cdd3..814733ba2f4b 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -1597,6 +1597,10 @@ static int ocfs2_rename(struct mnt_idmap *idmap,
 	if (update_dot_dot) {
 		status = ocfs2_update_entry(old_inode, handle,
 					    &old_inode_dot_dot_res, new_dir);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
 		drop_nlink(old_dir);
 		if (new_inode) {
 			drop_nlink(new_inode);
@@ -1636,6 +1640,10 @@ static int ocfs2_rename(struct mnt_idmap *idmap,
 							 INODE_CACHE(old_dir),
 							 old_dir_bh,
 							 OCFS2_JOURNAL_ACCESS_WRITE);
+			if (status < 0) {
+				mlog_errno(status);
+				goto bail;
+			}
 			fe = (struct ocfs2_dinode *) old_dir_bh->b_data;
 			ocfs2_set_links_count(fe, old_dir->i_nlink);
 			ocfs2_journal_dirty(handle, old_dir_bh);
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index dfaae1e52412..e09842fc9d4d 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -1240,6 +1240,10 @@ int ocfs2_create_local_dquot(struct dquot *dquot)
 				     &od->dq_local_phys_blk,
 				     &pcount,
 				     NULL);
+	if (status < 0) {
+		mlog_errno(status);
+		goto out;
+	}
 
 	/* Initialize dquot structure on disk */
 	status = ocfs2_local_write_dquot(dquot);
diff --git a/fs/pipe.c b/fs/pipe.c
index 8916c455a469..804a7d789452 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -864,7 +864,7 @@ void free_pipe_info(struct pipe_inode_info *pipe)
 	kfree(pipe);
 }
 
-static struct vfsmount *pipe_mnt __read_mostly;
+static struct vfsmount *pipe_mnt __ro_after_init;
 
 /*
  * pipefs_dname() is called from d_path().
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 2c2efbe685d8..ff08a8957552 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -536,12 +536,13 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 
 		/* add up live thread stats at the group level */
 		if (whole) {
-			struct task_struct *t = task;
-			do {
+			struct task_struct *t;
+
+			__for_each_thread(sig, t) {
 				min_flt += t->min_flt;
 				maj_flt += t->maj_flt;
 				gtime += task_gtime(t);
-			} while_each_thread(task, t);
+			}
 
 			min_flt += sig->min_flt;
 			maj_flt += sig->maj_flt;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 83396ab14998..dd31e3b6bf77 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1153,11 +1153,10 @@ err_unlock:
 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
 			     size_t count, loff_t *ppos)
 {
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int oom_adj;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count)) {
@@ -1213,11 +1212,10 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
 					size_t count, loff_t *ppos)
 {
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int oom_score_adj;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count)) {
@@ -1358,13 +1356,13 @@ static ssize_t proc_fault_inject_write(struct file * file,
 			const char __user * buf, size_t count, loff_t *ppos)
 {
 	struct task_struct *task;
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int make_it_fail;
 	int rv;
 
 	if (!capable(CAP_SYS_RESOURCE))
 		return -EPERM;
-	memset(buffer, 0, sizeof(buffer));
+
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count))
@@ -1509,11 +1507,10 @@ sched_autogroup_write(struct file *file, const char __user *buf,
 {
 	struct inode *inode = file_inode(file);
 	struct task_struct *p;
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int nice;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count))
@@ -1666,10 +1663,9 @@ static ssize_t comm_write(struct file *file, const char __user *buf,
 {
 	struct inode *inode = file_inode(file);
 	struct task_struct *p;
-	char buffer[TASK_COMM_LEN];
+	char buffer[TASK_COMM_LEN] = {};
 	const size_t maxlen = sizeof(buffer) - 1;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
 		return -EFAULT;
 
@@ -2976,8 +2972,7 @@ static const struct file_operations proc_coredump_filter_operations = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
 {
-	struct task_io_accounting acct = task->ioac;
-	unsigned long flags;
+	struct task_io_accounting acct;
 	int result;
 
 	result = down_read_killable(&task->signal->exec_update_lock);
@@ -2989,15 +2984,28 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
 		goto out_unlock;
 	}
 
-	if (whole && lock_task_sighand(task, &flags)) {
-		struct task_struct *t = task;
+	if (whole) {
+		struct signal_struct *sig = task->signal;
+		struct task_struct *t;
+		unsigned int seq = 1;
+		unsigned long flags;
+
+		rcu_read_lock();
+		do {
+			seq++; /* 2 on the 1st/lockless path, otherwise odd */
+			flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
 
-		task_io_accounting_add(&acct, &task->signal->ioac);
-		while_each_thread(task, t)
-			task_io_accounting_add(&acct, &t->ioac);
+			acct = sig->ioac;
+			__for_each_thread(sig, t)
+				task_io_accounting_add(&acct, &t->ioac);
 
-		unlock_task_sighand(task, &flags);
+		} while (need_seqretry(&sig->stats_lock, seq));
+		done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
+		rcu_read_unlock();
+	} else {
+		acct = task->ioac;
 	}
+
 	seq_printf(m,
 		   "rchar: %llu\n"
 		   "wchar: %llu\n"
@@ -3818,7 +3826,7 @@ static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
 	for_each_thread(task, pos) {
 		if (!nr--)
 			goto found;
-	};
+	}
 fail:
 	pos = NULL;
 	goto out;
@@ -3840,10 +3848,8 @@ static struct task_struct *next_tid(struct task_struct *start)
 	struct task_struct *pos = NULL;
 	rcu_read_lock();
 	if (pid_alive(start)) {
-		pos = next_thread(start);
-		if (thread_group_leader(pos))
-			pos = NULL;
-		else
+		pos = __next_thread(start);
+		if (pos)
 			get_task_struct(pos);
 	}
 	rcu_read_unlock();
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 592ed2516f47..b33e490e3fd9 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -110,18 +110,15 @@ void __init proc_init_kmemcache(void)
 
 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
 {
-	struct inode *inode;
-	struct proc_inode *ei;
 	struct hlist_node *node;
 	struct super_block *old_sb = NULL;
 
 	rcu_read_lock();
-	for (;;) {
+	while ((node = hlist_first_rcu(inodes))) {
+		struct proc_inode *ei = hlist_entry(node, struct proc_inode, sibling_inodes);
 		struct super_block *sb;
-		node = hlist_first_rcu(inodes);
-		if (!node)
-			break;
-		ei = hlist_entry(node, struct proc_inode, sibling_inodes);
+		struct inode *inode;
+
 		spin_lock(lock);
 		hlist_del_init_rcu(&ei->sibling_inodes);
 		spin_unlock(lock);
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 4abd51053f76..ef2eb12906da 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -851,9 +851,7 @@ static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
 static int show_smap(struct seq_file *m, void *v)
 {
 	struct vm_area_struct *vma = v;
-	struct mem_size_stats mss;
-
-	memset(&mss, 0, sizeof(mss));
+	struct mem_size_stats mss = {};
 
 	smap_gather_stats(vma, &mss, 0);
 
@@ -879,7 +877,7 @@ static int show_smap(struct seq_file *m, void *v)
 static int show_smaps_rollup(struct seq_file *m, void *v)
 {
 	struct proc_maps_private *priv = m->private;
-	struct mem_size_stats mss;
+	struct mem_size_stats mss = {};
 	struct mm_struct *mm = priv->mm;
 	struct vm_area_struct *vma;
 	unsigned long vma_start = 0, last_vma_end = 0;
@@ -895,8 +893,6 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
 		goto out_put_task;
 	}
 
-	memset(&mss, 0, sizeof(mss));
-
 	ret = mmap_read_lock_killable(mm);
 	if (ret)
 		goto out_put_mm;
@@ -1248,14 +1244,13 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
 	struct task_struct *task;
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
 	enum clear_refs_types type;
 	int itype;
 	int rv;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count))
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index ac616cfbacf5..e8af40b05549 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -49,7 +49,7 @@ static struct ctl_table vm_userfaultfd_table[] = {
 };
 #endif
 
-static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
+static struct kmem_cache *userfaultfd_ctx_cachep __ro_after_init;
 
 /*
  * Start with fault_pending_wqh and fault_wqh so they're more likely