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Message-Id: <20250703021004.42328-4-feng.tang@linux.alibaba.com>
Date: Thu, 3 Jul 2025 10:10:02 +0800
From: Feng Tang <feng.tang@...ux.alibaba.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Lance Yang <lance.yang@...ux.dev>,
Jonathan Corbet <corbet@....net>,
linux-kernel@...r.kernel.org
Cc: paulmck@...nel.org,
john.ogness@...utronix.de,
Feng Tang <feng.tang@...ux.alibaba.com>
Subject: [PATCH 3/5] panic: add 'panic_sys_info' sysctl to take human readable string parameter
Bitmap definition for 'panic_print' is hard to remember and decode.
Add 'panic_sys_info='sysctl to take human readable string like
"tasks,mem,timers,locks,ftrace,..." and translate it into bitmap.
The detailed mapping is:
SYS_INFO_TASKS "tasks"
SYS_INFO_MEM "mem"
SYS_INFO_TIMERS "timers"
SYS_INFO_LOCKS "locks"
SYS_INFO_FTRACE "ftrace"
SYS_INFO_ALL_CPU_BT "all_bt"
SYS_INFO_BLOCKED_TASKS "blocked_tasks"
Suggested-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Feng Tang <feng.tang@...ux.alibaba.com>
---
Documentation/admin-guide/sysctl/kernel.rst | 18 +++++
include/linux/sys_info.h | 8 ++
kernel/panic.c | 7 ++
lib/sys_info.c | 90 +++++++++++++++++++++
4 files changed, 123 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 0d08b7a2db2d..cccb06d1a6bf 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -899,6 +899,24 @@ So for example to print tasks and memory info on panic, user can::
echo 3 > /proc/sys/kernel/panic_print
+panic_sys_info
+==============
+
+A comma separated list of extra information to be dumped on panic,
+for example, "tasks,mem,timers,...". It is a human readable alternative
+to 'panic_print'. Possible values are:
+
+============= ===================================================
+tasks print all tasks info
+mem print system memory info
+timer print timers info
+lock print locks info if CONFIG_LOCKDEP is on
+ftrace print ftrace buffer
+all_bt print all CPUs backtrace (if available in the arch)
+blocked_tasks print only tasks in uninterruptible (blocked) state
+============= ===================================================
+
+
panic_on_rcu_stall
==================
diff --git a/include/linux/sys_info.h b/include/linux/sys_info.h
index 53b7e27dbf2a..89d77dc4f2ed 100644
--- a/include/linux/sys_info.h
+++ b/include/linux/sys_info.h
@@ -2,6 +2,8 @@
#ifndef _LINUX_SYS_INFO_H
#define _LINUX_SYS_INFO_H
+#include <linux/sysctl.h>
+
/*
* SYS_INFO_PANIC_CONSOLE_REPLAY is for panic case only, as it needs special
* handling which only fits panic case.
@@ -16,5 +18,11 @@
#define SYS_INFO_BLOCKED_TASKS 0x00000080
void sys_info(unsigned long si_mask);
+unsigned long sys_info_parse_param(char *str);
+#ifdef CONFIG_SYSCTL
+int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
+ void *buffer, size_t *lenp,
+ loff_t *ppos);
+#endif
#endif /* _LINUX_SYS_INFO_H */
diff --git a/kernel/panic.c b/kernel/panic.c
index cbb0681177b3..d7aa427dc23c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -126,6 +126,13 @@ static const struct ctl_table kern_panic_table[] = {
.mode = 0644,
.proc_handler = proc_douintvec,
},
+ {
+ .procname = "panic_sys_info",
+ .data = &panic_print,
+ .maxlen = sizeof(panic_print),
+ .mode = 0644,
+ .proc_handler = sysctl_sys_info_handler,
+ },
};
static __init int kernel_panic_sysctls_init(void)
diff --git a/lib/sys_info.c b/lib/sys_info.c
index 53031e5cb98e..46d6f4f1ad2a 100644
--- a/lib/sys_info.c
+++ b/lib/sys_info.c
@@ -3,10 +3,100 @@
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/ftrace.h>
+#include <linux/sysctl.h>
#include <linux/nmi.h>
#include <linux/sys_info.h>
+struct sys_info_name {
+ unsigned long bit;
+ const char *name;
+};
+
+/*
+ * When 'si_names' gets updated, please make sure the 'sys_info_avail'
+ * below is updated accordingly.
+ */
+static const struct sys_info_name si_names[] = {
+ { SYS_INFO_TASKS, "tasks" },
+ { SYS_INFO_MEM, "mem" },
+ { SYS_INFO_TIMERS, "timers" },
+ { SYS_INFO_LOCKS, "locks" },
+ { SYS_INFO_FTRACE, "ftrace" },
+ { SYS_INFO_ALL_CPU_BT, "all_bt" },
+ { SYS_INFO_BLOCKED_TASKS, "blocked_tasks" },
+};
+
+/* Expecting string like "xxx_sys_info=tasks,mem,timers,locks,ftrace,..." */
+unsigned long sys_info_parse_param(char *str)
+{
+ unsigned long si_bits = 0;
+ char *s, *name;
+ int i;
+
+ s = str;
+ while ((name = strsep(&s, ",")) && *name) {
+ for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+ if (!strcmp(name, si_names[i].name)) {
+ si_bits |= si_names[i].bit;
+ break;
+ }
+ }
+ }
+
+ return si_bits;
+}
+
+#ifdef CONFIG_SYSCTL
+
+static const char sys_info_avail[] = "tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks";
+
+int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
+ void *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ char names[sizeof(sys_info_avail) + 1];
+ struct ctl_table table;
+ unsigned long *si_bits_global;
+
+ si_bits_global = ro_table->data;
+
+ if (write) {
+ unsigned long si_bits;
+ int ret;
+
+ table = *ro_table;
+ table.data = names;
+ table.maxlen = sizeof(names);
+ ret = proc_dostring(&table, write, buffer, lenp, ppos);
+ if (ret)
+ return ret;
+
+ si_bits = sys_info_parse_param(names);
+ /* The access to the global value is not synchronized. */
+ WRITE_ONCE(*si_bits_global, si_bits);
+ return 0;
+ } else {
+ /* for 'read' operation */
+ char *delim = "";
+ int i, len = 0;
+
+ for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+ if (*si_bits_global & si_names[i].bit) {
+ len += scnprintf(names + len, sizeof(names) - len,
+ "%s%s", delim, si_names[i].name);
+ delim = ",";
+ }
+ }
+
+ table = *ro_table;
+ table.data = names;
+ table.maxlen = sizeof(names);
+ return proc_dostring(&table, write, buffer, lenp, ppos);
+ }
+}
+#endif
+
void sys_info(unsigned long si_mask)
{
if (si_mask & SYS_INFO_TASKS)
--
2.43.5
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