From: Feng Tang <feng.tang@xxxxxxxxx> Subject: kernel/sysctl: add panic_print into sysctl So that we can also runtime chose to print out the needed system info for panic, other than setting the kernel cmdline. Link: http://lkml.kernel.org/r/1543398842-19295-3-git-send-email-feng.tang@xxxxxxxxx Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx> Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: John Stultz <john.stultz@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/sysctl/kernel.txt | 17 +++++++++++++++++ include/linux/kernel.h | 1 + include/uapi/linux/sysctl.h | 1 + kernel/panic.c | 2 +- kernel/sysctl.c | 7 +++++++ kernel/sysctl_binary.c | 1 + 6 files changed, 28 insertions(+), 1 deletion(-) --- a/Documentation/sysctl/kernel.txt~kernel-sysctl-add-panic_print-into-sysctl +++ a/Documentation/sysctl/kernel.txt @@ -60,6 +60,7 @@ show up in /proc/sys/kernel: - panic_on_stackoverflow - panic_on_unrecovered_nmi - panic_on_warn +- panic_print - panic_on_rcu_stall - perf_cpu_time_max_percent - perf_event_paranoid @@ -654,6 +655,22 @@ a kernel rebuild when attempting to kdum ============================================================== +panic_print: + +Bitmask for printing system info when panic happens. User can chose +combination of the following bits: + +bit 0: print all tasks info +bit 1: print system memory info +bit 2: print timer info +bit 3: print locks info if CONFIG_LOCKDEP is on +bit 4: print ftrace buffer + +So for example to print tasks and memory info on panic, user can: + echo 3 > /proc/sys/kernel/panic_print + +============================================================== + panic_on_rcu_stall: When set to 1, calls panic() after RCU stall detection messages. This --- a/include/linux/kernel.h~kernel-sysctl-add-panic_print-into-sysctl +++ a/include/linux/kernel.h @@ -527,6 +527,7 @@ static inline u32 int_sqrt64(u64 x) extern void bust_spinlocks(int yes); extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */ extern int panic_timeout; +extern unsigned long panic_print; extern int panic_on_oops; extern int panic_on_unrecovered_nmi; extern int panic_on_io_nmi; --- a/include/uapi/linux/sysctl.h~kernel-sysctl-add-panic_print-into-sysctl +++ a/include/uapi/linux/sysctl.h @@ -153,6 +153,7 @@ enum KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */ KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */ KERN_PANIC_ON_WARN=77, /* int: call panic() in WARN() functions */ + KERN_PANIC_PRINT=78, /* ulong: bitmask to print system info on panic */ }; --- a/kernel/panic.c~kernel-sysctl-add-panic_print-into-sysctl +++ a/kernel/panic.c @@ -51,7 +51,7 @@ EXPORT_SYMBOL_GPL(panic_timeout); #define PANIC_PRINT_TIMER_INFO 0x00000004 #define PANIC_PRINT_LOCK_INFO 0x00000008 #define PANIC_PRINT_FTRACE_INFO 0x00000010 -static unsigned long panic_print; +unsigned long panic_print; ATOMIC_NOTIFIER_HEAD(panic_notifier_list); --- a/kernel/sysctl_binary.c~kernel-sysctl-add-panic_print-into-sysctl +++ a/kernel/sysctl_binary.c @@ -140,6 +140,7 @@ static const struct bin_table bin_kern_t { CTL_INT, KERN_MAX_LOCK_DEPTH, "max_lock_depth" }, { CTL_INT, KERN_PANIC_ON_NMI, "panic_on_unrecovered_nmi" }, { CTL_INT, KERN_PANIC_ON_WARN, "panic_on_warn" }, + { CTL_ULONG, KERN_PANIC_PRINT, "panic_print" }, {} }; --- a/kernel/sysctl.c~kernel-sysctl-add-panic_print-into-sysctl +++ a/kernel/sysctl.c @@ -807,6 +807,13 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "panic_print", + .data = &panic_print, + .maxlen = sizeof(unsigned long), + .mode = 0644, + .proc_handler = proc_doulongvec_minmax, + }, #if defined CONFIG_PRINTK { .procname = "printk", _
