Re: [PATCH -next] arm64/kdump: Update the high memory reserve doc

[Catalin Marinas <catalin.marinas@arm.com>]

On Tue, Aug 06, 2024 at 07:33:20PM +0800, Jinjie Ruan wrote:
> Since commit 282c3a66b724 ("crash: Fix riscv64 crash memory reserve dead
> loop"), if reservation from the high memory failed on ARM64, the kernel
> will not falls back to searching the low memory, so remove it in the doc.

This commit doesn't exist in -next. I found it with a different hash but
don't add it in the commit log here.

> diff --git a/Documentation/arch/arm64/kdump.rst b/Documentation/arch/arm64/kdump.rst
> index 56a89f45df28..11b9b84bf422 100644
> --- a/Documentation/arch/arm64/kdump.rst
> +++ b/Documentation/arch/arm64/kdump.rst
> @@ -79,10 +79,6 @@ To reserve memory for crashkernel=size,high, searching is first
>  attempted from the high memory region. If the reservation succeeds, the
>  low memory reservation will be done subsequently.
>  
> -If reservation from the high memory failed, the kernel falls back to
> -searching the low memory with the specified size in crashkernel=,high.
> -If it succeeds, no further reservation for low memory is needed.

I recall long discussions over a year ago where the conclusion was that
for sysadmins it's easier to have crashkernel=,high the default with
fallback to lowmem. No need to worry about how much low or high memory
there is on a SoC, just specify a preference for high memory.

Can we not have a different fix for the infinite loop problem while we
preserve the fallback behaviour?

-- 
Catalin