linux-kernel - Re: [PATCH v5 11/16] kexec: add config option for KHO

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Message-ID: <CALu+AoQj+mHECTvbuK8CpUTmOYgx6n2oMFm5kQXtSigL+5Ks2w@mail.gmail.com>
Date: Tue, 25 Mar 2025 16:36:22 +0800
From: Dave Young <dyoung@...hat.com>
To: Baoquan He <bhe@...hat.com>
Cc: Changyuan Lyu <changyuanl@...gle.com>, linux-kernel@...r.kernel.org, graf@...zon.com, 
	akpm@...ux-foundation.org, luto@...nel.org, anthony.yznaga@...cle.com, 
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Subject: Re: [PATCH v5 11/16] kexec: add config option for KHO

> >
> > Have you tested kdump?  In my mind there are two issues,  one is with
> > CMA enabled, it could cause kdump crashkernel memory reservation
> > failures more often due to the fragmented low memory.  Secondly,  in
>
> kho scracth memorys are reserved much later than crashkernel, we may not
> need to worry about it.
> ====================
> start_kernel()
>   ......
>   -->setup_arch(&command_line);
>      -->arch_reserve_crashkernel();
>   ......
>   -->mm_core_init();
>      -->kho_memory_init();
>
> > kdump kernel dump the crazy scratch memory in vmcore is not very
> > meaningful.  Otherwise I suspect this is not tested under kdump.  If
> > so please disable this option for kdump.

Ok,  it is fine if this is the case, thanks Baoquan for clearing this worry.

But the other concerns are still need to address, eg. KHO use cases
are not good for kdump.
There could be more to think about.
eg. the issues talked in thread:
https://lore.kernel.org/lkml/Z7dc9Cd8KX3b_brB@dwarf.suse.cz/T/