Merge tag 'mm-nonmm-stable-2023-02-20-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:
 "There is no particular theme here - mainly quick hits all over the
  tree.

  Most notable is a set of zlib changes from Mikhail Zaslonko which
  enhances and fixes zlib's use of S390 hardware support: 'lib/zlib: Set
  of s390 DFLTCC related patches for kernel zlib'"

* tag 'mm-nonmm-stable-2023-02-20-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (55 commits)
  Update CREDITS file entry for Jesper Juhl
  sparc: allow PM configs for sparc32 COMPILE_TEST
  hung_task: print message when hung_task_warnings gets down to zero.
  arch/Kconfig: fix indentation
  scripts/tags.sh: fix the Kconfig tags generation when using latest ctags
  nilfs2: prevent WARNING in nilfs_dat_commit_end()
  lib/zlib: remove redundation assignement of avail_in dfltcc_gdht()
  lib/Kconfig.debug: do not enable DEBUG_PREEMPT by default
  lib/zlib: DFLTCC always switch to software inflate for Z_PACKET_FLUSH option
  lib/zlib: DFLTCC support inflate with small window
  lib/zlib: Split deflate and inflate states for DFLTCC
  lib/zlib: DFLTCC not writing header bits when avail_out == 0
  lib/zlib: fix DFLTCC ignoring flush modes when avail_in == 0
  lib/zlib: fix DFLTCC not flushing EOBS when creating raw streams
  lib/zlib: implement switching between DFLTCC and software
  lib/zlib: adjust offset calculation for dfltcc_state
  nilfs2: replace WARN_ONs for invalid DAT metadata block requests
  scripts/spelling.txt: add "exsits" pattern and fix typo instances
  fs: gracefully handle ->get_block not mapping bh in __mpage_writepage
  cramfs: Kconfig: fix spelling & punctuation
  ...

6 files changed, 111 insertions, 7 deletions

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index c71889f3f3fc..322813366c6c 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -142,6 +142,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 
 		if (sysctl_hung_task_all_cpu_backtrace)
 			hung_task_show_all_bt = true;
+		if (!sysctl_hung_task_warnings)
+			pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n");
 	}
 
 	touch_nmi_watchdog();
diff --git a/kernel/kexec.c b/kernel/kexec.c
index cb8e6e6f983c..92d301f98776 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -190,10 +190,12 @@ out_unlock:
 static inline int kexec_load_check(unsigned long nr_segments,
 				   unsigned long flags)
 {
+	int image_type = (flags & KEXEC_ON_CRASH) ?
+			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
 	int result;
 
 	/* We only trust the superuser with rebooting the system. */
-	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
+	if (!kexec_load_permitted(image_type))
 		return -EPERM;
 
 	/* Permit LSMs and IMA to fail the kexec */
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index b1cf259854ca..3d578c6fefee 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -921,10 +921,64 @@ int kimage_load_segment(struct kimage *image,
 	return result;
 }
 
+struct kexec_load_limit {
+	/* Mutex protects the limit count. */
+	struct mutex mutex;
+	int limit;
+};
+
+static struct kexec_load_limit load_limit_reboot = {
+	.mutex = __MUTEX_INITIALIZER(load_limit_reboot.mutex),
+	.limit = -1,
+};
+
+static struct kexec_load_limit load_limit_panic = {
+	.mutex = __MUTEX_INITIALIZER(load_limit_panic.mutex),
+	.limit = -1,
+};
+
 struct kimage *kexec_image;
 struct kimage *kexec_crash_image;
-int kexec_load_disabled;
+static int kexec_load_disabled;
+
 #ifdef CONFIG_SYSCTL
+static int kexec_limit_handler(struct ctl_table *table, int write,
+			       void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct kexec_load_limit *limit = table->data;
+	int val;
+	struct ctl_table tmp = {
+		.data = &val,
+		.maxlen = sizeof(val),
+		.mode = table->mode,
+	};
+	int ret;
+
+	if (write) {
+		ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
+		if (ret)
+			return ret;
+
+		if (val < 0)
+			return -EINVAL;
+
+		mutex_lock(&limit->mutex);
+		if (limit->limit != -1 && val >= limit->limit)
+			ret = -EINVAL;
+		else
+			limit->limit = val;
+		mutex_unlock(&limit->mutex);
+
+		return ret;
+	}
+
+	mutex_lock(&limit->mutex);
+	val = limit->limit;
+	mutex_unlock(&limit->mutex);
+
+	return proc_dointvec(&tmp, write, buffer, lenp, ppos);
+}
+
 static struct ctl_table kexec_core_sysctls[] = {
 	{
 		.procname	= "kexec_load_disabled",
@@ -936,6 +990,18 @@ static struct ctl_table kexec_core_sysctls[] = {
 		.extra1		= SYSCTL_ONE,
 		.extra2		= SYSCTL_ONE,
 	},
+	{
+		.procname	= "kexec_load_limit_panic",
+		.data		= &load_limit_panic,
+		.mode		= 0644,
+		.proc_handler	= kexec_limit_handler,
+	},
+	{
+		.procname	= "kexec_load_limit_reboot",
+		.data		= &load_limit_reboot,
+		.mode		= 0644,
+		.proc_handler	= kexec_limit_handler,
+	},
 	{ }
 };
 
@@ -947,6 +1013,32 @@ static int __init kexec_core_sysctl_init(void)
 late_initcall(kexec_core_sysctl_init);
 #endif
 
+bool kexec_load_permitted(int kexec_image_type)
+{
+	struct kexec_load_limit *limit;
+
+	/*
+	 * Only the superuser can use the kexec syscall and if it has not
+	 * been disabled.
+	 */
+	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
+		return false;
+
+	/* Check limit counter and decrease it.*/
+	limit = (kexec_image_type == KEXEC_TYPE_CRASH) ?
+		&load_limit_panic : &load_limit_reboot;
+	mutex_lock(&limit->mutex);
+	if (!limit->limit) {
+		mutex_unlock(&limit->mutex);
+		return false;
+	}
+	if (limit->limit != -1)
+		limit->limit--;
+	mutex_unlock(&limit->mutex);
+
+	return true;
+}
+
 /*
  * No panic_cpu check version of crash_kexec().  This function is called
  * only when panic_cpu holds the current CPU number; this is the only CPU
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index dd5983010b7b..f1a0e4e3fb5c 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -326,11 +326,13 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 		unsigned long, cmdline_len, const char __user *, cmdline_ptr,
 		unsigned long, flags)
 {
-	int ret = 0, i;
+	int image_type = (flags & KEXEC_FILE_ON_CRASH) ?
+			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
 	struct kimage **dest_image, *image;
+	int ret = 0, i;
 
 	/* We only trust the superuser with rebooting the system. */
-	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
+	if (!kexec_load_permitted(image_type))
 		return -EPERM;
 
 	/* Make sure we have a legal set of flags */
@@ -342,11 +344,12 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 	if (!kexec_trylock())
 		return -EBUSY;
 
-	dest_image = &kexec_image;
-	if (flags & KEXEC_FILE_ON_CRASH) {
+	if (image_type == KEXEC_TYPE_CRASH) {
 		dest_image = &kexec_crash_image;
 		if (kexec_crash_image)
 			arch_kexec_unprotect_crashkres();
+	} else {
+		dest_image = &kexec_image;
 	}
 
 	if (flags & KEXEC_FILE_UNLOAD)
diff --git a/kernel/kthread.c b/kernel/kthread.c
index f97fd01a2932..7e6751b29101 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -1382,6 +1382,10 @@ EXPORT_SYMBOL_GPL(kthread_flush_worker);
  * Flush and destroy @worker.  The simple flush is enough because the kthread
  * worker API is used only in trivial scenarios.  There are no multi-step state
  * machines needed.
+ *
+ * Note that this function is not responsible for handling delayed work, so
+ * caller should be responsible for queuing or canceling all delayed work items
+ * before invoke this function.
  */
 void kthread_destroy_worker(struct kthread_worker *worker)
 {
@@ -1393,6 +1397,7 @@ void kthread_destroy_worker(struct kthread_worker *worker)
 
 	kthread_flush_worker(worker);
 	kthread_stop(task);
+	WARN_ON(!list_empty(&worker->delayed_work_list));
 	WARN_ON(!list_empty(&worker->work_list));
 	kfree(worker);
 }
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 54211dbd516c..1d8e47bed3f1 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -229,7 +229,7 @@ void __put_user_ns(struct user_namespace *ns)
 EXPORT_SYMBOL(__put_user_ns);
 
 /**
- * idmap_key struct holds the information necessary to find an idmapping in a
+ * struct idmap_key - holds the information necessary to find an idmapping in a
  * sorted idmap array. It is passed to cmp_map_id() as first argument.
  */
 struct idmap_key {