Re: [PATCH v14 00/17] arm64/riscv: Add support for crashkernel CMA reservation

[Jinjie Ruan <ruanjinjie@huawei.com>]

On 5/25/2026 6:14 PM, Huacai Chen wrote:
> Hi, Jinjie,
> 
> On Mon, May 25, 2026 at 4:50 PM Jinjie Ruan <ruanjinjie@huawei.com> 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.
>>
>> Also add support for arm64 crash hotplug.
>>
>> This patch set is rebased on v7.1-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=4G crashkernel=64M,cma"
>>
>> For first kernel, there will be such log:
>>
>>         # dmesg | grep crash
>>         [    0.000000] crashkernel low memory reserved: 0xe8000000 - 0xf0000000 (128 MB)
>>         [    0.000000] crashkernel reserved: 0x000000023e600000 - 0x000000033e600000 (4096 MB)
>>         [    0.000000] crashkernel CMA reserved: 64 MB in 1 ranges
>>
>>         # dmesg | grep cma
>>         [    0.000000] cma: Reserved 256 MiB at 0x00000000f0000000
>>         [    0.000000] cma: Reserved 64 MiB at 0x0000000100000000
>>
>> For second kernel, there will be such log:
>>
>>         [    0.000000] OF: fdt: Looking for usable-memory-range property...
>>         [    0.000000] OF: fdt: cap_mem_regions[0]: base=0x000000023e600000, size=0x0000000100000000
>>         [    0.000000] OF: fdt: cap_mem_regions[1]: base=0x00000000e8000000, size=0x0000000008000000
>>         [    0.000000] OF: fdt: cap_mem_regions[2]: base=0x0000000100000000, size=0x0000000004000000
>>
>> Changes in v14:
>> - Fix image->elf_headers memory leak during retry loop for arm64 as Sashiko
>>   AI code review pointed out.
>> - Solve the hotplug notifier arch_crash_handle_hotplug_event() AA
>>   self-deadlock problem as Sashiko AI code review pointed out.
>> - Fix the TOCTOU issue in prepare_elf_headers() by get_online_mems().
>> - -ENOMEM -> -EAGAIN as Breno suggested.
>> - Add support for arm64 crash hotplug.
>> - Link to v13: https://lore.kernel.org/all/20260511030454.1730881-1-ruanjinjie@huawei.com/
>>
>> Changes in v13:
>> - Rebased on v7.1-rc1.
>> - Update the commit message.
>> - Add Reviewed-by.
>> - Link to v12: https://lore.kernel.org/all/20260402072701.628293-1-ruanjinjie@huawei.com/
>>
>> 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.
>> - 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 (16):
>>   riscv: kexec_file: Fix crashk_low_res not exclude bug
>>   powerpc/crash: Fix possible memory leak in update_crash_elfcorehdr()
>>   arm64: kexec: Fix image->elf_headers memory leak during retry loop
>>   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
>>   arm64/crash: Add crash hotplug support
> I have some bikesheedings about the subjects. Can we unify the prefix formats?
> x86/kexec, arm64: kexec_file, riscv: kexec_file, LoongArch: kexec .....
> 
> Huacai

Sure, will update it in next version.

> 
>>
>> Sourabh Jain (1):
>>   powerpc/crash: sort crash memory ranges before preparing elfcorehdr
>>
>>  .../admin-guide/kernel-parameters.txt         |  16 +--
>>  arch/arm64/Kconfig                            |   3 +
>>  arch/arm64/include/asm/kexec.h                |  14 +-
>>  arch/arm64/kernel/Makefile                    |   1 +
>>  arch/arm64/kernel/crash.c                     | 125 ++++++++++++++++++
>>  arch/arm64/kernel/kexec_image.c               |  22 ++-
>>  arch/arm64/kernel/machine_kexec_file.c        |  78 ++++++-----
>>  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                    |  11 ++
>>  include/linux/crash_reserve.h                 |   4 +-
>>  kernel/crash_core.c                           | 102 +++++++++++++-
>>  20 files changed, 392 insertions(+), 298 deletions(-)
>>  create mode 100644 arch/arm64/kernel/crash.c
>>
>> --
>> 2.34.1
>>
>