linux-kernel - Re: [PATCH v5] crash: export crashkernel CMA reservation to userspace

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: <20251117094211.f8b4426ddda3bc0db5a62624@linux-foundation.org>
Date: Mon, 17 Nov 2025 09:42:11 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Sourabh Jain <sourabhjain@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, Aditya Gupta <adityag@...ux.ibm.com>,
 Baoquan he <bhe@...hat.com>, Dave Young <dyoung@...hat.com>, Hari Bathini
 <hbathini@...ux.ibm.com>, Jiri Bohac <jbohac@...e.cz>, Madhavan Srinivasan
 <maddy@...ux.ibm.com>, Mahesh J Salgaonkar <mahesh@...ux.ibm.com>, Pingfan
 Liu <piliu@...hat.com>, "Ritesh Harjani (IBM)" <ritesh.list@...il.com>,
 Shivang Upadhyay <shivangu@...ux.ibm.com>, Vivek Goyal <vgoyal@...hat.com>,
 linuxppc-dev@...ts.ozlabs.org, kexec@...ts.infradead.org
Subject: Re: [PATCH v5] crash: export crashkernel CMA reservation to
 userspace

On Mon, 17 Nov 2025 09:49:05 +0530 Sourabh Jain <sourabhjain@...ux.ibm.com> wrote:

> Add a sysfs entry /sys/kernel/kexec/crash_cma_ranges to expose all
> CMA crashkernel ranges.
> 
> This allows userspace tools configuring kdump to determine how much
> memory is reserved for crashkernel. If CMA is used, tools can warn
> users when attempting to capture user pages with CMA reservation.
> 
> The new sysfs hold the CMA ranges in below format:
> 
> cat /sys/kernel/kexec/crash_cma_ranges
> 100000000-10c7fffff
> 
> There are already four kexec and kdump sysfs entries under /sys/kernel.
> Adding more entries there would clutter the directory. To avoid this,
> the new crash_cma_ranges sysfs entry is placed in a new kexec node under
> /sys/kernel/.

I suggest not creating /sys/kernel/kexec in this patch.

Moving everything into a new /sys/kernel/kexec is a separate patchset
and a separate concept and it might never be merged - it changes ABI!

So let's put crash_cma_ranges in /sys/kernel and move it to
/sys/kernel/kexec within the other patchset.