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
  ...

1 files changed, 15 insertions, 4 deletions

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 3b28cff24cc1..3499c1a8b929 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -707,15 +707,26 @@ bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
 	return p1->signal == p2->signal;
 }
 
-static inline struct task_struct *next_thread(const struct task_struct *p)
+/*
+ * returns NULL if p is the last thread in the thread group
+ */
+static inline struct task_struct *__next_thread(struct task_struct *p)
+{
+	return list_next_or_null_rcu(&p->signal->thread_head,
+					&p->thread_node,
+					struct task_struct,
+					thread_node);
+}
+
+static inline struct task_struct *next_thread(struct task_struct *p)
 {
-	return list_entry_rcu(p->thread_group.next,
-			      struct task_struct, thread_group);
+	return __next_thread(p) ?: p->group_leader;
 }
 
 static inline int thread_group_empty(struct task_struct *p)
 {
-	return list_empty(&p->thread_group);
+	return thread_group_leader(p) &&
+	       list_is_last(&p->thread_node, &p->signal->thread_head);
 }
 
 #define delay_group_leader(p) \