Messages in this thread Patch in this message | | | From | Vincent Whitchurch <> | Subject | [PATCH v2] sysctl: Add panic-fatal-signals | Date | Mon, 28 Jan 2019 09:49:59 +0100 |
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Add a sysctl which asks the kernel to panic when any userspace process receives a fatal signal which would trigger a core dump. This has proven to be quite useful when debugging problems seen during testing of embedded systems: When combined with kernel core dumps (saved due to the panic), it allows easier debugging of crashes which have their origin in system-wide problems such as buggy drivers or other kernel or hardware-related issues.
The crashing process's core dump can be extracted from the kernel core dump using tools such as the crash utility's gcore extension.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> --- v2: Put the sysctl behind a config option
include/linux/signal.h | 1 + init/Kconfig | 14 ++++++++++++++ kernel/signal.c | 5 ++++- kernel/sysctl.c | 9 +++++++++ 4 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/include/linux/signal.h b/include/linux/signal.h index cc7e2c1cd444..109efd1432e9 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -10,6 +10,7 @@ struct task_struct; /* for sysctl */ extern int print_fatal_signals; +extern int panic_fatal_signals; static inline void copy_siginfo(kernel_siginfo_t *to, const kernel_siginfo_t *from) diff --git a/init/Kconfig b/init/Kconfig index d47cb77a220e..875442f6ab53 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1242,6 +1242,20 @@ config SYSCTL_SYSCALL If unsure say N here. +config SYSCTL_PANIC_FATAL_SIGNALS + bool "panic-fatal-signals sysctl" if EXPERT + depends on PROC_SYSCTL + help + If you say Y here, a kernel.panic-fatal-signals sysctl will be + offered. If this sysctl is turned on, the kernel will panic if any + userspace process receives a fatal signal which would trigger a core + dump. + + When used together with kernel core dumps, this can be useful for + debugging some system-wide problems, primarily on embedded systems. + + If unsure, say N. + config FHANDLE bool "open by fhandle syscalls" if EXPERT select EXPORTFS diff --git a/kernel/signal.c b/kernel/signal.c index e1d7ad8e6ab1..83c6877b0182 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -59,6 +59,7 @@ static struct kmem_cache *sigqueue_cachep; int print_fatal_signals __read_mostly; +int panic_fatal_signals __read_mostly; static void __user *sig_handler(struct task_struct *t, int sig) { @@ -2497,8 +2498,10 @@ bool get_signal(struct ksignal *ksig) current->flags |= PF_SIGNALED; if (sig_kernel_coredump(signr)) { - if (print_fatal_signals) + if (print_fatal_signals || panic_fatal_signals) print_fatal_signal(ksig->info.si_signo); + if (panic_fatal_signals) + panic("Fatal signal and panic_fatal_signals=1"); proc_coredump_connector(current); /* * If it was able to dump core, this kills all diff --git a/kernel/sysctl.c b/kernel/sysctl.c index ba4d9e85feb8..48023bad5b08 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -557,6 +557,15 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, +#ifdef CONFIG_SYSCTL_PANIC_FATAL_SIGNALS + { + .procname = "panic-fatal-signals", + .data = &panic_fatal_signals, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, +#endif #ifdef CONFIG_SPARC { .procname = "reboot-cmd", -- 2.20.0
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