Date:   Tue, 14 Dec 2021 20:07:58 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Zhen Lei <thunder.leizhen@huawei.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org,
        Dave Young <dyoung@redhat.com>, Baoquan He <bhe@redhat.com>,
        Vivek Goyal <vgoyal@redhat.com>,
        Eric Biederman <ebiederm@xmission.com>,
        kexec@lists.infradead.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        devicetree@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        linux-doc@vger.kernel.org, Randy Dunlap <rdunlap@infradead.org>,
        Feng Zhou <zhoufeng.zf@bytedance.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Chen Zhou <dingguo.cz@antgroup.com>
Subject: Re: [PATCH v17 02/10] x86: kdump: make the lower bound of crash
 kernel reservation consistent
Message-ID: <YbjrjpehprvoRXbV@zn.tnic>
References: <20211210065533.2023-1-thunder.leizhen@huawei.com>
 <20211210065533.2023-3-thunder.leizhen@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20211210065533.2023-3-thunder.leizhen@huawei.com>
Precedence: bulk

On Fri, Dec 10, 2021 at 02:55:25PM +0800, Zhen Lei wrote:
> From: Chen Zhou <chenzhou10@huawei.com>
> 
> The lower bounds of crash kernel reservation and crash kernel low
> reservation are different, use the consistent value CRASH_ALIGN.

A big WHY is missing here to explain why the lower bound of the
allocation range needs to be 16M and why was 0 wrong?

> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 5cc60996eac56d6..6424ee4f23da2cf 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -441,7 +441,8 @@ static int __init reserve_crashkernel_low(void)
>  			return 0;
>  	}
>  
> -	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> +	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, CRASH_ALIGN,
> +			CRASH_ADDR_LOW_MAX);

You don't have to break this line.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette