Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - The series "powerpc/crash: use generic crashkernel reservation" from
   Sourabh Jain changes powerpc's kexec code to use more of the generic
   layers.

 - The series "get_maintainer: report subsystem status separately" from
   Vlastimil Babka makes some long-requested improvements to the
   get_maintainer output.

 - The series "ucount: Simplify refcounting with rcuref_t" from
   Sebastian Siewior cleans up and optimizing the refcounting in the
   ucount code.

 - The series "reboot: support runtime configuration of emergency
   hw_protection action" from Ahmad Fatoum improves the ability for a
   driver to perform an emergency system shutdown or reboot.

 - The series "Converge on using secs_to_jiffies() part two" from Easwar
   Hariharan performs further migrations from msecs_to_jiffies() to
   secs_to_jiffies().

 - The series "lib/interval_tree: add some test cases and cleanup" from
   Wei Yang permits more userspace testing of kernel library code, adds
   some more tests and performs some cleanups.

 - The series "hung_task: Dump the blocking task stacktrace" from Masami
   Hiramatsu arranges for the hung_task detector to dump the stack of
   the blocking task and not just that of the blocked task.

 - The series "resource: Split and use DEFINE_RES*() macros" from Andy
   Shevchenko provides some cleanups to the resource definition macros.

 - Plus the usual shower of singleton patches - please see the
   individual changelogs for details.

* tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits)
  mailmap: consolidate email addresses of Alexander Sverdlin
  fs/procfs: fix the comment above proc_pid_wchan()
  relay: use kasprintf() instead of fixed buffer formatting
  resource: replace open coded variant of DEFINE_RES()
  resource: replace open coded variants of DEFINE_RES_*_NAMED()
  resource: replace open coded variant of DEFINE_RES_NAMED_DESC()
  resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED()
  samples: add hung_task detector mutex blocking sample
  hung_task: show the blocker task if the task is hung on mutex
  kexec_core: accept unaccepted kexec segments' destination addresses
  watchdog/perf: optimize bytes copied and remove manual NUL-termination
  lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap()
  lib/interval_tree: skip the check before go to the right subtree
  lib/interval_tree: add test case for span iteration
  lib/interval_tree: add test case for interval_tree_iter_xxx() helpers
  lib/rbtree: add random seed
  lib/rbtree: split tests
  lib/rbtree: enable userland test suite for rbtree related data structure
  checkpatch: describe --min-conf-desc-length
  scripts/gdb/symbols: determine KASLR offset on s390
  ...

1 files changed, 38 insertions, 0 deletions

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 04efa7a6e69b..dc898ec93463 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -93,6 +93,43 @@ static struct notifier_block panic_block = {
 	.notifier_call = hung_task_panic,
 };
 
+
+#ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER
+static void debug_show_blocker(struct task_struct *task)
+{
+	struct task_struct *g, *t;
+	unsigned long owner;
+	struct mutex *lock;
+
+	RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "No rcu lock held");
+
+	lock = READ_ONCE(task->blocker_mutex);
+	if (!lock)
+		return;
+
+	owner = mutex_get_owner(lock);
+	if (unlikely(!owner)) {
+		pr_err("INFO: task %s:%d is blocked on a mutex, but the owner is not found.\n",
+			task->comm, task->pid);
+		return;
+	}
+
+	/* Ensure the owner information is correct. */
+	for_each_process_thread(g, t) {
+		if ((unsigned long)t == owner) {
+			pr_err("INFO: task %s:%d is blocked on a mutex likely owned by task %s:%d.\n",
+				task->comm, task->pid, t->comm, t->pid);
+			sched_show_task(t);
+			return;
+		}
+	}
+}
+#else
+static inline void debug_show_blocker(struct task_struct *task)
+{
+}
+#endif
+
 static void check_hung_task(struct task_struct *t, unsigned long timeout)
 {
 	unsigned long switch_count = t->nvcsw + t->nivcsw;
@@ -152,6 +189,7 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 		pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
 			" disables this message.\n");
 		sched_show_task(t);
+		debug_show_blocker(t);
 		hung_task_show_lock = true;
 
 		if (sysctl_hung_task_all_cpu_backtrace)