linux-kernel - Re: [RFC][PATCH v2 22/29] mm/numa: Register information into Kmemdump

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Message-ID: <dd27cf00-b9b8-4231-a6d1-9ad6562d0074@redhat.com>
Date: Mon, 4 Aug 2025 14:16:41 +0200
From: David Hildenbrand <david@...hat.com>
To: Michal Hocko <mhocko@...e.com>
Cc: Eugen Hristev <eugen.hristev@...aro.org>, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, linux-arch@...r.kernel.org,
 linux-mm@...ck.org, tglx@...utronix.de, andersson@...nel.org,
 pmladek@...e.com, linux-arm-kernel@...ts.infradead.org,
 linux-hardening@...r.kernel.org, corbet@....net, mojha@....qualcomm.com,
 rostedt@...dmis.org, jonechou@...gle.com, tudor.ambarus@...aro.org
Subject: Re: [RFC][PATCH v2 22/29] mm/numa: Register information into Kmemdump

On 04.08.25 12:54, Michal Hocko wrote:
> On Wed 30-07-25 16:04:28, David Hildenbrand wrote:
>> On 30.07.25 15:57, Eugen Hristev wrote:
> [...]
>>> Yes, registering after is also an option. Initially this is how I
>>> designed the kmemdump API, I also had in mind to add a flag, but, after
>>> discussing with Thomas Gleixner, he came up with the macro wrapper idea
>>> here:
>>> https://lore.kernel.org/lkml/87ikkzpcup.ffs@tglx/
>>> Do you think we can continue that discussion , or maybe start it here ?
>>
>> Yeah, I don't like that, but I can see how we ended up here.
>>
>> I also don't quite like the idea that we must encode here what to include in
>> a dump and what not ...
>>
>> For the vmcore we construct it at runtime in crash_save_vmcoreinfo_init(),
>> where we e.g., have
>>
>> VMCOREINFO_STRUCT_SIZE(pglist_data);
>>
>> Could we similar have some place where we construct what to dump similarly,
>> just not using the current values, but the memory ranges?
> 
> All those symbols are part of kallsyms, right? Can we just use kallsyms
> infrastructure and a list of symbols to get what we need from there?
> 
> In other words the list of symbols to be completely external to the code
> that is defining them?

That was the idea. All we should need is the start+size of the ranges. 
No need to have these kmemdump specifics all over the kernel.

-- 
Cheers,

David / dhildenb