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Commit f06e5153 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Linus Torvalds
Browse files

kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers 



Add a "crash_kexec_post_notifiers" boot option to run kdump after
running panic_notifiers and dump kmsg.  This can help rare situations
where kdump fails because of unstable crashed kernel or hardware failure
(memory corruption on critical data/code), or the 2nd kernel is already
broken by the 1st kernel (it's a broken behavior, but who can guarantee
that the "crashed" kernel works correctly?).

Usage: add "crash_kexec_post_notifiers" to kernel boot option.

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: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: default avatarMotohiro Kosaki <Motohiro.Kosaki@us.fujitsu.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Satoru MORIYA <satoru.moriya.br@hitachi.com>
Cc: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a219ccf4

Documentation/kernel-parameters.txt

+8 −0
Original line number Diff line number Diff line
@@ -2361,6 +2361,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			timeout < 0: reboot immediately

			Format: <timeout>



	crash_kexec_post_notifiers

			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.



	parkbd.port=	[HW] Parallel port number the keyboard adapter is

			connected to, default is 0.

			Format: <parport#>

kernel/panic.c

+21 −2
Original line number Diff line number Diff line
@@ -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 crash_kexec_post_notifiers;



int panic_timeout = CONFIG_PANIC_TIMEOUT;

EXPORT_SYMBOL_GPL(panic_timeout);
@@ -112,8 +113,10 @@ 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 run this after calling panic_notifiers, pass

	 * the "crash_kexec_post_notifiers" option to the kernel.

	 */

	if (!crash_kexec_post_notifiers)

		crash_kexec(NULL);



	/*
@@ -131,6 +134,15 @@ void panic(const char *fmt, ...) 


	kmsg_dump(KMSG_DUMP_PANIC);



	/*

	 * If you doubt kdump always works fine in any situation,

	 * "crash_kexec_post_notifiers" offers you a chance to run

	 * panic_notifiers and dumping kmsg before kdump.

	 * Note: since some panic_notifiers can make crashed kernel

	 * more unstable, it can increase risks of the kdump failure too.

	 */

	crash_kexec(NULL);



	bust_spinlocks(0);



	if (!panic_blink)
@@ -472,6 +484,13 @@ EXPORT_SYMBOL(__stack_chk_fail); 
core_param(panic, panic_timeout, int, 0644);

core_param(pause_on_oops, pause_on_oops, int, 0644);



static int __init setup_crash_kexec_post_notifiers(char *s)

{

	crash_kexec_post_notifiers = true;

	return 0;

}

early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);



static int __init oops_setup(char *s)

{

	if (!s)