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 <[email protected]>
---
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;
return 0;
diff --git a/kernel/panic.c b/kernel/panic.c
index 4d8d6f9..6582546 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -32,7 +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;
+bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly;
int panic_timeout = CONFIG_PANIC_TIMEOUT;
--
1.9.3
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 <[email protected]>
> ---
> 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.
> return 0;
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 4d8d6f9..6582546 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -32,7 +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;
> +bool crash_kexec_post_notifiers;
> int panic_on_warn __read_mostly;
>
> int panic_timeout = CONFIG_PANIC_TIMEOUT;
> --
> 1.9.3
>
>
>
> _______________________________________________
> kexec mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/kexec
Hello,
From: Baoquan He <[email protected]>
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 <[email protected]>
>> ---
>> 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)
--
Thanks.
HATAYAMA, Daisuke
On 02/09/15 at 12:22pm, HATAYAMA Daisuke wrote:
> Hello,
>
> From: Baoquan He <[email protected]>
> 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 <[email protected]>
> >> ---
> >> 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 <[email protected]>
Thanks
Baoquan
>
> --
> Thanks.
> HATAYAMA, Daisuke
>
Hello,
(2015/02/09 12:29), Baoquan He wrote:> On 02/09/15 at 12:22pm, HATAYAMA Daisuke wrote:
>> From: Baoquan He <[email protected]>
>>> On 02/05/15 at 05:59pm, HATAYAMA Daisuke wrote:
>>>> 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 <[email protected]>
Thanks for the patch!
I tested it in following cases on x86_64 and it worked well;
my panic notifier was called, then 2nd kernel booted.
- Null pointer dereference in each context of
- hard IRQ
- pid == 0
- pid == 1
- others with panic_on_oops=1
- Zero-divide in the context of normal process
(panic_on_oops=1)
Tested-by: Hidehiro Kawai <[email protected]>
--
Hidehiro Kawai
Hitachi, Yokohama Research Laboratory
Hello Eric, Vivek,
Do you have any comment to this patch?
On 2015/02/05 17:59, 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 <[email protected]>
> ---
> 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;
> return 0;
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 4d8d6f9..6582546 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -32,7 +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;
> +bool crash_kexec_post_notifiers;
> int panic_on_warn __read_mostly;
>
> int panic_timeout = CONFIG_PANIC_TIMEOUT;
>
--
Thanks.
HATAYAMA, Daisuke