Re: [merged mm-nonmm-stable] riscv-kexec-add-support-for-crashkernel-cma-reservation.patch removed from -mm tree

[Mike Rapoport <rppt@kernel.org>]

Hi Andrew,

On Sat, Jan 31, 2026 at 04:17:10PM -0800, Andrew Morton wrote:
> 
> The quilt patch titled
>      Subject: riscv: kexec: add support for crashkernel CMA reservation
> has been removed from the -mm tree.  Its filename was
>      riscv-kexec-add-support-for-crashkernel-cma-reservation.patch
> 
> This patch was dropped because it was merged into the mm-nonmm-stable branch
> of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> ------------------------------------------------------
> From: Jinjie Ruan <ruanjinjie@huawei.com>
> Subject: riscv: kexec: add support for crashkernel CMA reservation
> Date: Mon, 26 Jan 2026 16:07:38 +0800

I commented on almost identical patch for arm64 

https://lore.kernel.org/all/20260126081334.699147-1-ruanjinjie@huawei.com/

about moving the exclusion of CMA regions into the core crash code.
The same comment applies to this one as well. Sorry I didn't mention that
more explicitly.
 
> Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the crashkernel=
> command line option") and commit ab475510e042 ("kdump: implement
> reserve_crashkernel_cma") added CMA support for kdump crashkernel
> reservation.  This allows the kernel to dynamically allocate contiguous
> memory for crash dumping when needed, rather than permanently reserving a
> fixed region at boot time.
> 
> So extend crashkernel CMA reservation support to riscv.  The following
> changes are made to enable CMA reservation:
> 
> - Parse and obtain the CMA reservation size along with other crashkernel
>   parameters.
> - Call reserve_crashkernel_cma() to allocate the CMA region for kdump.
> - Include the CMA-reserved ranges for kdump kernel to use.
> - Exclude the CMA-reserved ranges from the crash kernel memory to
>   prevent them from being exported through /proc/vmcore.
> 
> Update kernel-parameters.txt to document CMA support for crashkernel on
> riscv architecture.
> 
> Link: https://lkml.kernel.org/r/20260126080738.696723-1-ruanjinjie@huawei.com
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> Cc: Albert Ou <aou@eecs.berkeley.edu>
> Cc: Alexandre Ghiti <alex@ghiti.fr>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Björn Töpel <bjorn@rivosinc.com>
> Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
> Cc: Breno Leitao <leitao@debian.org>
> Cc: Frank van der Linden <fvdl@google.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Kees Cook <kees@kernel.org>
> Cc: Kevin Brodsky <kevin.brodsky@arm.com>
> Cc: Li RongQing <lirongqing@baidu.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Mike Rapoport <rppt@kernel.org>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Samuel Holland <samuel.holland@sifive.com>
> Cc: Song Shuai <songshuaishuai@tinylab.org>
> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> Cc: Yunhui Cui <cuiyunhui@bytedance.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  Documentation/admin-guide/kernel-parameters.txt |    2 -
>  arch/riscv/kernel/machine_kexec_file.c          |   17 ++++++++++++--
>  arch/riscv/mm/init.c                            |    5 ++--
>  3 files changed, 19 insertions(+), 5 deletions(-)
> 
> --- a/arch/riscv/kernel/machine_kexec_file.c~riscv-kexec-add-support-for-crashkernel-cma-reservation
> +++ a/arch/riscv/kernel/machine_kexec_file.c
> @@ -59,9 +59,9 @@ static int prepare_elf_headers(void **ad
>  {
>  	struct crash_mem *cmem;
>  	unsigned int nr_ranges;
> -	int ret;
> +	int ret, i;
>  
> -	nr_ranges = 1; /* For exclusion of crashkernel region */
> +	nr_ranges = 1 + crashk_cma_cnt; /* For exclusion of crashkernel region */
>  	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
>  
>  	cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
> @@ -74,11 +74,24 @@ static int prepare_elf_headers(void **ad
>  	if (ret)
>  		goto out;
>  
> +	for (i = 0; i < crashk_cma_cnt; i++) {
> +		cmem->ranges[cmem->nr_ranges].start = crashk_cma_ranges[i].start;
> +		cmem->ranges[cmem->nr_ranges].end = crashk_cma_ranges[i].end;
> +		cmem->nr_ranges++;
> +	}
> +
>  	/* Exclude crashkernel region */
>  	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
>  	if (!ret)
>  		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
>  
> +	for (i = 0; i < crashk_cma_cnt; ++i) {
> +		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> +					      crashk_cma_ranges[i].end);
> +		if (ret)
> +			goto out;
> +	}
> +
>  out:
>  	kfree(cmem);
>  	return ret;
> --- a/arch/riscv/mm/init.c~riscv-kexec-add-support-for-crashkernel-cma-reservation
> +++ a/arch/riscv/mm/init.c
> @@ -1404,7 +1404,7 @@ static inline void setup_vm_final(void)
>   */
>  static void __init arch_reserve_crashkernel(void)
>  {
> -	unsigned long long low_size = 0;
> +	unsigned long long low_size = 0, cma_size = 0;
>  	unsigned long long crash_base, crash_size;
>  	bool high = false;
>  	int ret;
> @@ -1414,11 +1414,12 @@ static void __init arch_reserve_crashker
>  
>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
>  				&crash_size, &crash_base,
> -				&low_size, NULL, &high);
> +				&low_size, &cma_size, &high);
>  	if (ret)
>  		return;
>  
>  	reserve_crashkernel_generic(crash_size, crash_base, low_size, high);
> +	reserve_crashkernel_cma(cma_size);
>  }
>  
>  void __init paging_init(void)
> --- a/Documentation/admin-guide/kernel-parameters.txt~riscv-kexec-add-support-for-crashkernel-cma-reservation
> +++ a/Documentation/admin-guide/kernel-parameters.txt
> @@ -1119,7 +1119,7 @@ Kernel parameters
>  			It will be ignored when crashkernel=X,high is not used
>  			or memory reserved is below 4G.
>  	crashkernel=size[KMG],cma
> -			[KNL, X86, ppc] Reserve additional crash kernel memory from
> +			[KNL, X86, RISCV, ppc] Reserve additional crash kernel memory from
>  			CMA. This reservation is usable by the first system's
>  			userspace memory and kernel movable allocations (memory
>  			balloon, zswap). Pages allocated from this memory range
> _
> 
> Patches currently in -mm which might be from ruanjinjie@huawei.com are
> 
> 

-- 
Sincerely yours,
Mike.