On 02/09/15 at 12:22pm, HATAYAMA Daisuke wrote: > Hello, > > From: Baoquan He <bhe at redhat.com> > Subject: Re: [PATCH] kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path > Date: Mon, 9 Feb 2015 10:40:30 +0800 > > > On 02/05/15 at 05:59pm, HATAYAMA Daisuke wrote: > >> The commit f06e5153f4ae2e2f3b0300f0e260e40cb7fefd45 introduced > >> "crash_kexec_post_notifiers" kernel boot option, which toggles > >> wheather panic() calls crash_kexec() before or after panic_notifiers > >> and dump kmsg. > >> > >> The problem is that the commit overlooks panic_on_oops kernel boot > >> option. If it is enabled, crash_kexec() is called directly without > >> going through panic() in oops path. > >> > >> To fix this issue, this patch adds a check to > >> "crash_kexec_post_notifiers" in the condition of kexec_should_crash(). > >> > >> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> > >> --- > >> include/linux/kernel.h | 3 +++ > >> kernel/kexec.c | 2 ++ > >> kernel/panic.c | 2 +- > >> 3 files changed, 6 insertions(+), 1 deletion(-) > >> > >> diff --git a/include/linux/kernel.h b/include/linux/kernel.h > >> index 64ce58b..f47379f 100644 > >> --- a/include/linux/kernel.h > >> +++ b/include/linux/kernel.h > >> @@ -426,6 +426,9 @@ extern int panic_on_unrecovered_nmi; > >> extern int panic_on_io_nmi; > >> extern int panic_on_warn; > >> extern int sysctl_panic_on_stackoverflow; > >> + > >> +extern bool crash_kexec_post_notifiers; > >> + > >> /* > >> * Only to be used by arch init code. If the user over-wrote the default > >> * CONFIG_PANIC_TIMEOUT, honor it. > >> diff --git a/kernel/kexec.c b/kernel/kexec.c > >> index 9a8a01a..0ecf252 100644 > >> --- a/kernel/kexec.c > >> +++ b/kernel/kexec.c > >> @@ -84,6 +84,8 @@ struct resource crashk_low_res = { > >> > >> int kexec_should_crash(struct task_struct *p) > >> { > >> + if (crash_kexec_post_notifiers) > >> + return 0; > >> if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops) > >> return 1; > > > > What if these two conditions !p->pid || is_global_init(p) are satisfied? > > Seems the behavious is changed. > > > > Please further follow do_exit() path. For each condition, there are > the corresponding panic() calls. In summary: > > oops_end > 1) panic() for in_interrupt() > 2) panic() for panic_on_oops > do_exit > 3) panic() for !p->pid (idle task) > exit_notify > forget_original_parent > find_child_reaper > 4) panic() for p->pid == 1 (init task) Yes, all conditions have been covered. So this patch is necessary, ACK it. Thanks Acked-by: Baoquan He <bhe at redhat.com> Thanks Baoquan > > -- > Thanks. > HATAYAMA, Daisuke >