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[PATCH V2] Documentation: Improve crash_kexec_post_notifiers description

Guilherme G. Piccoli posted 1 patch 1 year, 3 months ago
There is a newer version of this series
Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
[PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Guilherme G. Piccoli 1 year, 3 months ago 
Be more clear about the downsides, the upsides (yes, there are some!)
and about code that unconditionally sets that.

Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

---

V2: Some wording improvements from Stephen, thanks!
Also added his review tag.

V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/


 Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index efc52ddc6864..351730108c58 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -913,12 +913,16 @@
 			the parameter has no effect.
 
 	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.
+			Only jump to kdump kernel after running the panic
+			notifiers and dumping kmsg. This option increases the
+			risks of a kdump failure, since some panic notifiers
+			can make the crashed kernel more unstable. In the
+			configurations where kdump may not be reliable,
+			running the panic notifiers can allow collecting more
+			data on dmesg, like stack traces from other CPUS or
+			extra data dumped by panic_print. Notice that some
+			code enables this option unconditionally, like
+			Hyper-V, PowerPC (fadump) and AMD SEV.
 
 	crashkernel=size[KMG][@offset[KMG]]
 			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
-- 
2.46.0
Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Simon Horman 1 year, 3 months ago 
On Fri, Aug 30, 2024 at 03:21:00PM -0300, Guilherme G. Piccoli wrote:
> Be more clear about the downsides, the upsides (yes, there are some!)
> and about code that unconditionally sets that.
> 
> Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> 
> ---
> 
> V2: Some wording improvements from Stephen, thanks!
> Also added his review tag.
> 
> V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/
> 
> 
>  Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 

Hi Guilherme,

Some subjective grammar nits.

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index efc52ddc6864..351730108c58 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -913,12 +913,16 @@
>  			the parameter has no effect.
>  
>  	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.
> +			Only jump to kdump kernel after running the panic
> +			notifiers and dumping kmsg. This option increases the
> +			risks of a kdump failure, since some panic notifiers
> +			can make the crashed kernel more unstable. In the

nit: In the configurations -> In configurations

> +			configurations where kdump may not be reliable,
> +			running the panic notifiers can allow collecting more
> +			data on dmesg, like stack traces from other CPUS or
> +			extra data dumped by panic_print. Notice that some

nit: Notice that -> Note that

> +			code enables this option unconditionally, like

Maybe: some code enables -> some configurations enable

> +			Hyper-V, PowerPC (fadump) and AMD SEV.
>  
>  	crashkernel=size[KMG][@offset[KMG]]
>  			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
> -- 
> 2.46.0
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
>
Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Guilherme G. Piccoli 1 year, 3 months ago 
On 02/09/2024 10:23, Simon Horman wrote:
> 
> Hi Guilherme,
> 
> Some subjective grammar nits.
> 
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index efc52ddc6864..351730108c58 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -913,12 +913,16 @@
>>  			the parameter has no effect.
>>  
>>  	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.
>> +			Only jump to kdump kernel after running the panic
>> +			notifiers and dumping kmsg. This option increases the
>> +			risks of a kdump failure, since some panic notifiers
>> +			can make the crashed kernel more unstable. In the
> 
> nit: In the configurations -> In configurations
> 
>> +			configurations where kdump may not be reliable,
>> +			running the panic notifiers can allow collecting more
>> +			data on dmesg, like stack traces from other CPUS or
>> +			extra data dumped by panic_print. Notice that some
> 
> nit: Notice that -> Note that
> 
>> +			code enables this option unconditionally, like
> 
> Maybe: some code enables -> some configurations enable
> 

Hey Simon, tnx for the suggestions, will change in the next version.
Cheers,


Guilherme
Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Baoquan He 1 year, 3 months ago 
On 08/30/24 at 03:21pm, Guilherme G. Piccoli wrote:
> Be more clear about the downsides, the upsides (yes, there are some!)
> and about code that unconditionally sets that.
> 
> Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> 
> ---
> 
> V2: Some wording improvements from Stephen, thanks!
> Also added his review tag.
> 
> V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/
> 
> 
>  Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index efc52ddc6864..351730108c58 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -913,12 +913,16 @@
>  			the parameter has no effect.
>  
>  	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.
> +			Only jump to kdump kernel after running the panic
> +			notifiers and dumping kmsg. This option increases the
> +			risks of a kdump failure, since some panic notifiers
> +			can make the crashed kernel more unstable. In the
> +			configurations where kdump may not be reliable,
> +			running the panic notifiers can allow collecting more
> +			data on dmesg, like stack traces from other CPUS or
> +			extra data dumped by panic_print. Notice that some
> +			code enables this option unconditionally, like
> +			Hyper-V, PowerPC (fadump) and AMD SEV.
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I know Hyper-V enable panic-notifiers by default, but don't remember how
PowerPC and AMD SEC behave in this aspect. While at it, can you add a
little more words to state them in log so that people can learn it?
Thanks.

>  
>  	crashkernel=size[KMG][@offset[KMG]]
>  			[KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
> -- 
> 2.46.0
>
Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Guilherme G. Piccoli 1 year, 3 months ago 
On 02/09/2024 05:05, Baoquan He wrote:
> On 08/30/24 at 03:21pm, Guilherme G. Piccoli wrote:
>> Be more clear about the downsides, the upsides (yes, there are some!)
>> and about code that unconditionally sets that.
>>
>> Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
>> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
>>
>> ---
>>
>> V2: Some wording improvements from Stephen, thanks!
>> Also added his review tag.
>>
>> V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/
>>
>>
>>  Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
>>  1 file changed, 10 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index efc52ddc6864..351730108c58 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -913,12 +913,16 @@
>>  			the parameter has no effect.
>>  
>>  	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.
>> +			Only jump to kdump kernel after running the panic
>> +			notifiers and dumping kmsg. This option increases the
>> +			risks of a kdump failure, since some panic notifiers
>> +			can make the crashed kernel more unstable. In the
>> +			configurations where kdump may not be reliable,
>> +			running the panic notifiers can allow collecting more
>> +			data on dmesg, like stack traces from other CPUS or
>> +			extra data dumped by panic_print. Notice that some
>> +			code enables this option unconditionally, like
>> +			Hyper-V, PowerPC (fadump) and AMD SEV.
>                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> I know Hyper-V enable panic-notifiers by default, but don't remember how
> PowerPC and AMD SEC behave in this aspect. While at it, can you add a
> little more words to state them in log so that people can learn it?
> Thanks.
> 
Hi Baoquan, tnx for the suggestion! You mean mention that in the commit
message? If so, I can certainly do - will sent a new version soon(tm)
and include it =)

Cheers,


Guilherme
Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers description
Posted by Baoquan He 1 year, 3 months ago 
On 09/11/24 at 05:09pm, Guilherme G. Piccoli wrote:
> On 02/09/2024 05:05, Baoquan He wrote:
> > On 08/30/24 at 03:21pm, Guilherme G. Piccoli wrote:
> >> Be more clear about the downsides, the upsides (yes, there are some!)
> >> and about code that unconditionally sets that.
> >>
> >> Reviewed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> >> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> >>
> >> ---
> >>
> >> V2: Some wording improvements from Stephen, thanks!
> >> Also added his review tag.
> >>
> >> V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/
> >>
> >>
> >>  Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
> >>  1 file changed, 10 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> >> index efc52ddc6864..351730108c58 100644
> >> --- a/Documentation/admin-guide/kernel-parameters.txt
> >> +++ b/Documentation/admin-guide/kernel-parameters.txt
> >> @@ -913,12 +913,16 @@
> >>  			the parameter has no effect.
> >>  
> >>  	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.
> >> +			Only jump to kdump kernel after running the panic
> >> +			notifiers and dumping kmsg. This option increases the
> >> +			risks of a kdump failure, since some panic notifiers
> >> +			can make the crashed kernel more unstable. In the
> >> +			configurations where kdump may not be reliable,
> >> +			running the panic notifiers can allow collecting more
> >> +			data on dmesg, like stack traces from other CPUS or
> >> +			extra data dumped by panic_print. Notice that some
> >> +			code enables this option unconditionally, like
> >> +			Hyper-V, PowerPC (fadump) and AMD SEV.
> >                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > I know Hyper-V enable panic-notifiers by default, but don't remember how
> > PowerPC and AMD SEC behave in this aspect. While at it, can you add a
> > little more words to state them in log so that people can learn it?
> > Thanks.
> > 
> Hi Baoquan, tnx for the suggestion! You mean mention that in the commit
> message? If so, I can certainly do - will sent a new version soon(tm)
> and include it =)

You are right, thanks for the effort.

Patchew 2.1-devel-b67e4c2

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