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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date: Sun, 24 Mar 2024 05:06:57 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Baoquan He <bhe@redhat.com>
Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, x86@kernel.org,
	akpm@linux-foundation.org, chenhuacai@loongson.cn,
	dyoung@redhat.com, jbohac@suse.cz, lihuafei1@huawei.com,
	chenhaixiang3@huawei.com
Subject: Re: [PATCH] crash: use macro to add crashk_res into iomem early for
 specific arch
Message-ID: <Zf+m4YtKtmdrjw4Q@gmail.com>
References: <20240324033513.1027427-1-bhe@redhat.com>
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* Baoquan He <bhe@redhat.com> wrote:

> There are regression reports[1][2] that crashkernel region on x86_64 can't
> be added into iomem tree sometime. This causes the later failure of kdump
> loading.
> 
> This happened after commit 4a693ce65b18 ("kdump: defer the insertion of
> crashkernel resources") was merged.
> 
> Even though, these reported issues are proved to be related to other
> component, they are just exposed after above commmit applied, I still
> would like to keep crashk_res and crashk_low_res being added into iomem
> early as before because the early adding has been always there on x86_64
> and working very well. For safety of kdump, Let's change it back.
> 
> Here, add a macro HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY to limit that
> only ARCH defining the macro can have the early adding
> crashk_res/_low_res into iomem. Then define
> HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY on x86 to enable it.
> 
> Note: In reserve_crashkernel_low(), there's a remnant of crashk_low_res
> hanlding which was mistakenly added back in commit 85fcde402db1 ("kexec:
> split crashkernel reservation code out from crash_core.c").
> 
> [1]
> [PATCH V2] x86/kexec: do not update E820 kexec table for setup_data
> https://lore.kernel.org/all/Zfv8iCL6CT2JqLIC@darkstar.users.ipa.redhat.com/T/#u
> 
> [2]
> Question about Address Range Validation in Crash Kernel Allocation
> https://lore.kernel.org/all/4eeac1f733584855965a2ea62fa4da58@huawei.com/T/#u
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/x86/include/asm/crash_reserve.h | 2 ++
>  kernel/crash_reserve.c               | 7 +++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/arch/x86/include/asm/crash_reserve.h b/arch/x86/include/asm/crash_reserve.h
> index 152239f95541..4681a543eba3 100644
> --- a/arch/x86/include/asm/crash_reserve.h
> +++ b/arch/x86/include/asm/crash_reserve.h
> @@ -39,4 +39,6 @@ static inline unsigned long crash_low_size_default(void)
>  #endif
>  }
>  
> +# define HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
> +

Any reason for that stray space?

Thanks,

	Ingo