Merge tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - "ida: Remove the ida_simple_xxx() API" from Christophe Jaillet
   completes the removal of this legacy IDR API

 - "panic: introduce panic status function family" from Jinchao Wang
   provides a number of cleanups to the panic code and its various
   helpers, which were rather ad-hoc and scattered all over the place

 - "tools/delaytop: implement real-time keyboard interaction support"
   from Fan Yu adds a few nice user-facing usability changes to the
   delaytop monitoring tool

 - "efi: Fix EFI boot with kexec handover (KHO)" from Evangelos
   Petrongonas fixes a panic which was happening with the combination of
   EFI and KHO

 - "Squashfs: performance improvement and a sanity check" from Phillip
   Lougher teaches squashfs's lseek() about SEEK_DATA/SEEK_HOLE. A mere
   150x speedup was measured for a well-chosen microbenchmark

 - plus another 50-odd singleton patches all over the place

* tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (75 commits)
  Squashfs: reject negative file sizes in squashfs_read_inode()
  kallsyms: use kmalloc_array() instead of kmalloc()
  MAINTAINERS: update Sibi Sankar's email address
  Squashfs: add SEEK_DATA/SEEK_HOLE support
  Squashfs: add additional inode sanity checking
  lib/genalloc: fix device leak in of_gen_pool_get()
  panic: remove CONFIG_PANIC_ON_OOPS_VALUE
  ocfs2: fix double free in user_cluster_connect()
  checkpatch: suppress strscpy warnings for userspace tools
  cramfs: fix incorrect physical page address calculation
  kernel: prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit
  Squashfs: fix uninit-value in squashfs_get_parent
  kho: only fill kimage if KHO is finalized
  ocfs2: avoid extra calls to strlen() after ocfs2_sprintf_system_inode_name()
  kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths
  sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock
  coccinelle: platform_no_drv_owner: handle also built-in drivers
  coccinelle: of_table: handle SPI device ID tables
  lib/decompress: use designated initializers for struct compress_format
  efi: support booting with kexec handover (KHO)
  ...

1 files changed, 30 insertions, 2 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index a46d9b75880b..8b58eece4e58 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1734,6 +1734,7 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 	struct rlimit old, new;
 	struct task_struct *tsk;
 	unsigned int checkflags = 0;
+	bool need_tasklist;
 	int ret;
 
 	if (old_rlim)
@@ -1760,8 +1761,25 @@ SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
 	get_task_struct(tsk);
 	rcu_read_unlock();
 
-	ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
-			old_rlim ? &old : NULL);
+	need_tasklist = !same_thread_group(tsk, current);
+	if (need_tasklist) {
+		/*
+		 * Ensure we can't race with group exit or de_thread(),
+		 * so tsk->group_leader can't be freed or changed until
+		 * read_unlock(tasklist_lock) below.
+		 */
+		read_lock(&tasklist_lock);
+		if (!pid_alive(tsk))
+			ret = -ESRCH;
+	}
+
+	if (!ret) {
+		ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
+				old_rlim ? &old : NULL);
+	}
+
+	if (need_tasklist)
+		read_unlock(&tasklist_lock);
 
 	if (!ret && old_rlim) {
 		rlim_to_rlim64(&old, &old64);
@@ -2515,7 +2533,17 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			error = -EINVAL;
 			break;
 		}
+		/*
+		 * Ensure that either:
+		 *
+		 * 1. Subsequent getppid() calls reflect the parent process having died.
+		 * 2. forget_original_parent() will send the new me->pdeath_signal.
+		 *
+		 * Also prevent the read of me->pdeath_signal from being a data race.
+		 */
+		read_lock(&tasklist_lock);
 		me->pdeath_signal = arg2;
+		read_unlock(&tasklist_lock);
 		break;
 	case PR_GET_PDEATHSIG:
 		error = put_user(me->pdeath_signal, (int __user *)arg2);