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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZrJWarQnhFiM-e17@arm.com>
Date: Tue, 6 Aug 2024 17:59:22 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: will@...nel.org, corbet@....net, paul.walmsley@...ive.com,
	palmer@...belt.com, aou@...s.berkeley.edu,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH -next] arm64/kdump: Update the high memory reserve doc

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