On Mon, Apr 14, 2014 at 01:51:58PM +0900, Masami Hiramatsu wrote: > Add a "late_kdump" option to run kdump after running panic > notifiers and dump kmsg. This can help rare situations which > kdump drops in failure because of unstable crashed kernel > or hardware failure (memory corruption on critical data/code), > or the 2nd kernel is broken by the 1st kernel (it's a broken > behavior, but who can guarantee that the "crashed" kernel > works correctly?). > > Usage: add "late_kdump" to kernel boot option. That's all. > > Note that this actually increases risks of the failure of > kdump. This option should be set only if you worry about > the rare case of kdump failure rather than increasing the > chance of success. > > Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> > Cc: Eric Biederman <ebied...@xmission.com> > Cc: Vivek Goyal <vgo...@redhat.com> > Cc: Andrew Morton <a...@linux-foundation.org> > Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae...@hitachi.com> > Cc: Satoru MORIYA <satoru.moriya...@hitachi.com> > Cc: Motohiro Kosaki <motohiro.kos...@us.fujitsu.com> > Cc: Takenori Nagano <t-nag...@ah.jp.nec.com> > --- > Documentation/kernel-parameters.txt | 7 +++++++ > kernel/panic.c | 24 ++++++++++++++++++++++-- > 2 files changed, 29 insertions(+), 2 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt > b/Documentation/kernel-parameters.txt > index 03e50b4..1ba58da 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2339,6 +2339,13 @@ bytes respectively. Such letter suffixes can also be > entirely omitted. > timeout < 0: reboot immediately > Format: <timeout> > > + late_kdump Run kdump after running panic-notifiers and dumping > + kmsg. This only for the users who doubt kdump always > + succeeds in any situation. > + Note that this also increases risks of kdump failure, > + because some panic notifiers can make the crashed > + kernel more unstable. > +
I am wondering if "crash_kexec_post_notifiers" will be a better name to represent what we are trying to do here. > parkbd.port= [HW] Parallel port number the keyboard adapter is > connected to, default is 0. > Format: <parport#> > diff --git a/kernel/panic.c b/kernel/panic.c > index d02fa9f..bba42b5 100644 > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -32,6 +32,7 @@ static unsigned long tainted_mask; > static int pause_on_oops; > static int pause_on_oops_flag; > static DEFINE_SPINLOCK(pause_on_oops_lock); > +static bool late_kdump; > > int panic_timeout = CONFIG_PANIC_TIMEOUT; > EXPORT_SYMBOL_GPL(panic_timeout); > @@ -112,9 +113,14 @@ void panic(const char *fmt, ...) > /* > * If we have crashed and we have a crash kernel loaded let it handle > * everything else. > - * Do we want to call this before we try to display a message? > + * If we want to call this after we try to display a message, pass > + * the "late_kdump" option to the kernel. > */ > - crash_kexec(NULL); > + if (!late_kdump) > + crash_kexec(NULL); > + else > + pr_emerg("Warning: late_kdump option is set. Please DO NOT " > + "report bugs about kdump failure with this option.\n"); I think above message about DO NOT report bugs seems unnecessary. Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/