On Wed, 5 Nov 2014, Prarit Bhargava wrote: > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 6c0b9f2..bc4bd5a 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -471,6 +471,13 @@ format. Crash is available on Dave Anderson's site at the following URL: > > http://people.redhat.com/~anderson/ > > +Trigger Kdump on WARN() > +======================= > + > +The kernel parameter, panic_on_warn, calls panic() in all WARN() paths. This > +will cause a kdump to occur at the panic() call. In cases where a user wants > +to specify this during runtime, /proc/sys/kernel/panic_on_warn can be set to 1 > +to achieve the same behaviour. > > Contact > ======= > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 4c81a86..ea5d57c 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2509,6 +2509,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > timeout < 0: reboot immediately > Format: <timeout> > > + panic_on_warn panic() instead of WARN(). Useful to cause kdump > + on a WARN(). > + > crash_kexec_post_notifiers > Run kdump after running panic-notifiers and dumping > kmsg. This only for the users who doubt kdump always > diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt > index 57baff5..b5d0c85 100644 > --- a/Documentation/sysctl/kernel.txt > +++ b/Documentation/sysctl/kernel.txt > @@ -54,8 +54,9 @@ show up in /proc/sys/kernel: > - overflowuid > - panic > - panic_on_oops > -- panic_on_unrecovered_nmi > - panic_on_stackoverflow > +- panic_on_unrecovered_nmi > +- panic_on_warn > - pid_max > - powersave-nap [ PPC only ] > - printk > @@ -527,19 +528,6 @@ the recommended setting is 60. > > ============================================================== > > -panic_on_unrecovered_nmi: > - > -The default Linux behaviour on an NMI of either memory or unknown is > -to continue operation. For many environments such as scientific > -computing it is preferable that the box is taken out and the error > -dealt with than an uncorrected parity/ECC error get propagated. > - > -A small number of systems do generate NMI's for bizarre random reasons > -such as power management so the default is off. That sysctl works like > -the existing panic controls already in that directory. > - > -============================================================== > - > panic_on_oops: > > Controls the kernel's behaviour when an oops or BUG is encountered. > @@ -563,6 +551,30 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled. > > ============================================================== > > +panic_on_unrecovered_nmi: > + > +The default Linux behaviour on an NMI of either memory or unknown is > +to continue operation. For many environments such as scientific > +computing it is preferable that the box is taken out and the error > +dealt with than an uncorrected parity/ECC error get propagated. > + > +A small number of systems do generate NMI's for bizarre random reasons > +such as power management so the default is off. That sysctl works like > +the existing panic controls already in that directory. > + > +============================================================== > + > +panic_on_warn: > + > +Calls panic() in the WARN() path when set to 1. This is useful to avoid > +a kernel rebuild when attempting to kdump at the location of a WARN(). > + > +0: only WARN(), default behaviour. > + > +1: call panic() after printing out WARN() location. > + > +============================================================== > + > perf_cpu_time_max_percent: > > Hints to the kernel how much CPU time it should be allowed to > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 3d770f55..d60d31d 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -422,6 +422,7 @@ extern int panic_timeout; > extern int panic_on_oops; > extern int panic_on_unrecovered_nmi; > extern int panic_on_io_nmi; > +extern int panic_on_warn; > extern int sysctl_panic_on_stackoverflow; > /* > * Only to be used by arch init code. If the user over-wrote the default > diff --git a/include/uapi/linux/sysctl.h b/include/uapi/linux/sysctl.h > index 43aaba1..0956373 100644 > --- a/include/uapi/linux/sysctl.h > +++ b/include/uapi/linux/sysctl.h > @@ -153,6 +153,7 @@ enum > KERN_MAX_LOCK_DEPTH=74, /* int: rtmutex's maximum lock depth */ > 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 */ > }; > > > diff --git a/kernel/panic.c b/kernel/panic.c > index d09dc5c..c6a7723 100644 > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -33,6 +33,7 @@ static int pause_on_oops; > static int pause_on_oops_flag; > static DEFINE_SPINLOCK(pause_on_oops_lock); > static bool crash_kexec_post_notifiers; > +int panic_on_warn __read_mostly; > > int panic_timeout = CONFIG_PANIC_TIMEOUT; > EXPORT_SYMBOL_GPL(panic_timeout); > @@ -420,13 +421,23 @@ static void warn_slowpath_common(const char *file, int line, void *caller, > { > disable_trace_on_warning(); > > - pr_warn("------------[ cut here ]------------\n"); > + if (!panic_on_warn) > + pr_warn("------------[ cut here ]------------\n"); Is this really necessary? > pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", > raw_smp_processor_id(), current->pid, file, line, caller); > > if (args) > vprintk(args->fmt, args->args); > > + if (panic_on_warn) { > + /* > + * A flood of WARN()s may occur. Prevent further WARN()s > + * from panicking the system. > + */ What synchronization is preventing this race and further WARN()s panicking the system? > + panic_on_warn = 0; > + panic("panic_on_warn set ...\n"); > + } > + > print_modules(); > dump_stack(); > print_oops_end_marker();
