Re: [PATCH v12 00/15] arm64/riscv: Add support for crashkernel CMA reservation

[Jinjie Ruan <ruanjinjie@huawei.com>]

On 4/2/2026 3:26 PM, Jinjie Ruan wrote:
> The crash memory allocation, and the exclude of crashk_res, crashk_low_res
> and crashk_cma memory are almost identical across different architectures,
> This patch set handle them in crash core in a general way, which eliminate
> a lot of duplication code.
> 
> And add support for crashkernel CMA reservation for arm64 and riscv.
> 
> Rebased on v7.0-rc1.
> 
> Basic second kernel boot test were performed on QEMU platforms for x86,
> ARM64, and RISC-V architectures with the following parameters:
> 
> 	"cma=256M crashkernel=256M crashkernel=64M,cma"
> 
> Changes in v12:
> - Remove the unused "nr_mem_ranges" for x86.
> - Add "Fix crashk_low_res not exclude bug" test log.
> - Provide a separate patch for each architecture for using
>   crash_prepare_headers(), which will make the review more convenient.
> - Add Reviewed-by and Tested-by.
> - Link to v11: https://lore.kernel.org/all/20260328074013.3589544-1-ruanjinjie@huawei.com/
> 
> Changes in v11:
> - Avoid silently drop crash memory if the crash kernel is built without
>   CONFIG_CMA.
> - Remove unnecessary "cmem->nr_ranges = 0" for arch_crash_populate_cmem()
>   as we use kvzalloc().
> - Provide a separate patch for each architecture to fix the existing
>   buffer overflow issue.

Are there any further review comments? Especially regarding the patch
for fixing out-of-bounds access (suggested by the AI review), as well as
the changes for LoongArch, x86 and riscv architectures.

> - Add Acked-bys for arm64.
> 
> Changes in v10:
> - Fix crashk_low_res not excluded bug in the existing
>   RISC-V code.
> - Fix an existing memory leak issue in the existing PowerPC code.
> - Fix the ordering issue of adding CMA ranges to
>   "linux,usable-memory-range".
> - Fix an existing concurrency issue. A Concurrent memory hotplug may occur
>   between reading memblock and attempting to fill cmem during kexec_load()
>   for almost all existing architectures.
> - Link to v9: https://lore.kernel.org/all/20260323072745.2481719-1-ruanjinjie@huawei.com/
> 
> Changes in v9:
> - Collect Reviewed-by and Acked-by, and prepare for Sashiko AI review.
> - Link to v8: https://lore.kernel.org/all/20260302035315.3892241-1-ruanjinjie@huawei.com/
> 
> Changes in v8:
> - Fix the build issues reported by kernel test robot and Sourabh.
> - Link to v7: https://lore.kernel.org/all/20260226130437.1867658-1-ruanjinjie@huawei.com/
> 
> Changes in v7:
> - Correct the inclusion of CMA-reserved ranges for kdump kernel in of/kexec
>   for arm64 and riscv.
> - Add Acked-by.
> - Link to v6: https://lore.kernel.org/all/20260224085342.387996-1-ruanjinjie@huawei.com/
> 
> Changes in v6:
> - Update the crash core exclude code as Mike suggested.
> - Rebased on v7.0-rc1.
> - Add acked-by.
> - Link to v5: https://lore.kernel.org/all/20260212101001.343158-1-ruanjinjie@huawei.com/
> 
> Jinjie Ruan (14):
>   riscv: kexec_file: Fix crashk_low_res not exclude bug
>   powerpc/crash: Fix possible memory leak in update_crash_elfcorehdr()
>   x86/kexec: Fix potential buffer overflow in prepare_elf_headers()
>   arm64: kexec_file: Fix potential buffer overflow in
>     prepare_elf_headers()
>   riscv: kexec_file: Fix potential buffer overflow in
>     prepare_elf_headers()
>   LoongArch: kexec: Fix potential buffer overflow in
>     prepare_elf_headers()
>   crash: Add crash_prepare_headers() to exclude crash kernel memory
>   arm64: kexec_file: Use crash_prepare_headers() helper to simplify code
>   x86/kexec: Use crash_prepare_headers() helper to simplify code
>   riscv: kexec_file: Use crash_prepare_headers() helper to simplify code
>   LoongArch: kexec: Use crash_prepare_headers() helper to simplify code
>   crash: Use crash_exclude_core_ranges() on powerpc
>   arm64: kexec: Add support for crashkernel CMA reservation
>   riscv: kexec: Add support for crashkernel CMA reservation
> 
> Sourabh Jain (1):
>   powerpc/crash: sort crash memory ranges before preparing elfcorehdr
> 
>  .../admin-guide/kernel-parameters.txt         |  16 +--
>  arch/arm64/kernel/machine_kexec_file.c        |  43 +++-----
>  arch/arm64/mm/init.c                          |   5 +-
>  arch/loongarch/kernel/machine_kexec_file.c    |  43 +++-----
>  arch/powerpc/include/asm/kexec_ranges.h       |   1 -
>  arch/powerpc/kexec/crash.c                    |   7 +-
>  arch/powerpc/kexec/ranges.c                   | 101 +-----------------
>  arch/riscv/kernel/machine_kexec_file.c        |  42 +++-----
>  arch/riscv/mm/init.c                          |   5 +-
>  arch/x86/kernel/crash.c                       |  92 +++-------------
>  drivers/of/fdt.c                              |   9 +-
>  drivers/of/kexec.c                            |   9 ++
>  include/linux/crash_core.h                    |   9 ++
>  include/linux/crash_reserve.h                 |   4 +-
>  kernel/crash_core.c                           |  89 ++++++++++++++-
>  15 files changed, 193 insertions(+), 282 deletions(-)
>