linux-kernel - Re: [PATCH-RESEND] arm64/kexec: Fix missing extra range for crashkres

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Message-ID: <Yw2+H9MNpf3Ve0eJ@MiWiFi-R3L-srv>
Date:   Tue, 30 Aug 2022 15:37:03 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Yun Levi <ppbuk5246@...il.com>
Cc:     will@...nel.org, chenzhou10@...wei.com, nramas@...ux.microsoft.com,
        thunder.leizhen@...wei.com, linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kexec@...ts.infradead.org
Subject: Re: [PATCH-RESEND] arm64/kexec: Fix missing extra range for
 crashkres_low.

On 08/30/22 at 01:28pm, Yun Levi wrote:
> Like crashk_res, Calling crash_exclude_mem_range function with
> crashk_low_res area would need extra crash_mem range too.
> Add one extra crash_mem range when crashk_low_res is used.
> 
> Signed-off-by: Levi Yun <ppbuk5246@...il.com>
> ---
>  arch/arm64/kernel/machine_kexec_file.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/kernel/machine_kexec_file.c
> b/arch/arm64/kernel/machine_kexec_file.c
> index 889951291cc0..378aee04e7d4 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -51,6 +51,9 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>         for_each_mem_range(i, &start, &end)
>                 nr_ranges++;
> 
> +       if (crashk_low_res.end)
> +               nr_ranges++; /**< for exclusion of
> crashkernel=size,low region */
> +

Right, excluding crashkernel region may cause memory region splitting,
so we need extra slot for that.

Meanwhile, can you fix above code comment mess? Otherwise, this looks
good to me. 

Or we can add extra 2 slots like we do in x86, it just add another 16
bytes temporarily.


>         cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
>         if (!cmem)
>                 return -ENOMEM;
> --
> 2.35.1
>