+ sys_info-add-a-default-kernel-sys_info-mask.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: sys_info: add a default kernel sys_info mask
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     sys_info-add-a-default-kernel-sys_info-mask.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/sys_info-add-a-default-kernel-sys_info-mask.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Feng Tang <feng.tang@linux.alibaba.com>
Subject: sys_info: add a default kernel sys_info mask
Date: Thu, 13 Nov 2025 19:10:39 +0800

Which serves as a global default sys_info mask.  When users want the same
system information for many error cases (panic, hung, lockup ...), they
can chose to set this global knob only once, while not setting up each
individual sys_info knobs.

This just adds a 'lazy' option, and doesn't change existing kernel
behavior as the mask is 0 by default.

Link: https://lkml.kernel.org/r/20251113111039.22701-5-feng.tang@linux.alibaba.com
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/admin-guide/sysctl/kernel.rst |    9 +++++
 lib/sys_info.c                              |   31 +++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

--- a/Documentation/admin-guide/sysctl/kernel.rst~sys_info-add-a-default-kernel-sys_info-mask
+++ a/Documentation/admin-guide/sysctl/kernel.rst
@@ -521,6 +521,15 @@ default), only processes with the CAP_SY
 io_uring instances.
 
 
+kernel_sys_info
+===============
+A comma separated list of extra system information to be dumped when
+soft/hard lockup is detected, for example, "tasks,mem,timers,locks,...".
+Refer 'panic_sys_info' section below for more details.
+
+It serves as the default kernel control knob, which will take effect
+when a kernel module calls sys_info() with parameter==0.
+
 kexec_load_disabled
 ===================
 
--- a/lib/sys_info.c~sys_info-add-a-default-kernel-sys_info-mask
+++ a/lib/sys_info.c
@@ -24,6 +24,13 @@ static const char * const si_names[] = {
 	[ilog2(SYS_INFO_BLOCKED_TASKS)]		= "blocked_tasks",
 };
 
+/*
+ * Default kernel sys_info mask.
+ * If a kernel module calls sys_info() with "parameter == 0", then
+ * this mask will be used.
+ */
+static unsigned long kernel_si_mask;
+
 /* Expecting string like "xxx_sys_info=tasks,mem,timers,locks,ftrace,..." */
 unsigned long sys_info_parse_param(char *str)
 {
@@ -110,9 +117,26 @@ int sysctl_sys_info_handler(const struct
 	else
 		return sys_info_read_handler(&table, buffer, lenp, ppos, ro_table->data);
 }
+
+static const struct ctl_table sys_info_sysctls[] = {
+	{
+		.procname	= "kernel_sys_info",
+		.data		= &kernel_si_mask,
+		.maxlen         = sizeof(kernel_si_mask),
+		.mode		= 0644,
+		.proc_handler	= sysctl_sys_info_handler,
+	},
+};
+
+static int __init sys_info_sysctl_init(void)
+{
+	register_sysctl_init("kernel", sys_info_sysctls);
+	return 0;
+}
+subsys_initcall(sys_info_sysctl_init);
 #endif
 
-void sys_info(unsigned long si_mask)
+static void __sys_info(unsigned long si_mask)
 {
 	if (si_mask & SYS_INFO_TASKS)
 		show_state();
@@ -135,3 +159,8 @@ void sys_info(unsigned long si_mask)
 	if (si_mask & SYS_INFO_BLOCKED_TASKS)
 		show_state_filter(TASK_UNINTERRUPTIBLE);
 }
+
+void sys_info(unsigned long si_mask)
+{
+	__sys_info(si_mask ? : kernel_si_mask);
+}
_

Patches currently in -mm which might be from feng.tang@linux.alibaba.com are

docs-panic-correct-some-sys_ifo-names-in-sysctl-doc.patch
hung_task-add-hung_task_sys_info-sysctl-to-dump-sys-info-on-task-hung.patch
watchdog-add-sys_info-sysctls-to-dump-sys-info-on-system-lockup.patch
sys_info-add-a-default-kernel-sys_info-mask.patch