Re: [PATCH v4 00/10] kdump: reduce vmcore size and capture time

[Wandun <chenwandun1@gmail.com>]

On 6/30/26 15:47, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@lixiang.com>
> 
> On SoCs that carve out large firmware-owned reserved memory (GPU
> firmware, DSP, modem, camera ISP, NPU, ...), kdump currently dumps
> those carveouts as part of system RAM even though their contents are
> firmware state that is not useful for kernel crash analysis.
> 
> This series introduces an opt-in 'dumpable' flag [1] on struct
> reserved_mem and uses it to filter the elfcorehdr PT_LOAD ranges on
> DT-based architectures (arm64, riscv, loongarch). By default reserved
> regions are treated as non-dumpable; CMA regions are explicitly opted
> in because their pages are returned to the buddy allocator and may
> carry key crash-analysis data.
> 
> Since the reserved memory regions are filtered out, the vmcore is
> smaller in size and faster to produce. The reserved memory
> has already been filtered out in x86; the optimizations in this series
> apply to systems that use DTS such as arm64/riscv/loongarch.
> 
> The series is organized as follows:
> Patches 1-4: Small prepare changes and cleanups.
> Patches 5: Add dumpable flag to opt-in vmcore.
> Patches 6: Append /memreserve/ entries into reserved_mem[].
> Patch 7: Add generic kdump helpers.
> Patches 8-10: Wire the helpers into arm64, riscv and loongarch kdump
>               elfcorehdr preparation.

Hi Rob,

Gentle ping on this series. Patches 01, 05 and 07-10 have been
acked (thanks Pratyush, Will and Marek), and the comments there
have been addressed in my local tree.

Patch 02/03/04/06 are the core of: reserved_mem changes, they are still
pending review on the devicetree side.

Could you take a look when you have a chance? Happy to respin and
address any feedback.

Best regards,
Wandun


> 
> v3 --> v4:
> 1. Rebase this series on v7.2-rc1.
> 2. Add two cleanup patches (patch 02/03).
> 3. Simplify patch 03 to avoid checking whether initial_boot_params is
>    NULL multiple times, suggested by Rob.
> 
> v2 --> v3:
> 1. Fix out-of-bounds issue if device tree lacks /reserved-memory node.[2]
> 2. Fix UAF issue when alloc_reserved_mem_array() fails.
> 3. Add some prepare patches.
> 
> v1 --> v2:
> 1. v1 added an opt-out DT property ('linux,no-dump'). Per Rob's
>    feedback [1], v2 drop that property and exclude reserve memory
>    by default.
> 2. Split some prepared patches from the original patches.
> 3. Address coding-style comments on patch 5 from Rob.
> 
> [1] https://lore.kernel.org/lkml/20260506144542.GA2072596-robh@kernel.org/
> [2] https://sashiko.dev/#/patchset/20260520091844.592753-1-chenwandun%40lixiang.com?part=4
> 
> 
> Wandun Chen (10):
>   kexec/crash: provide crash_exclude_mem_range() stub when
>     CONFIG_CRASH_DUMP=n
>   of: reserved_mem: dedup and relocate reserved-memory messages
>   of: reserved_mem: skip late scan when no regions are reserved
>   of: reserved_mem: split alloc_reserved_mem_array() from
>     fdt_scan_reserved_mem_late()
>   of: reserved_mem: add dumpable flag to opt-in vmcore
>   of: reserved_mem: save /memreserve/ entries into the reserved_mem
>     array
>   of: reserved_mem: add kdump helpers to exclude non-dumpable regions
>   arm64: kdump: exclude non-dumpable reserved memory regions from vmcore
>   riscv: kdump: exclude non-dumpable reserved memory regions from vmcore
>   loongarch: kdump: exclude non-dumpable reserved memory regions from
>     vmcore
> 
>  arch/arm64/kernel/machine_kexec_file.c     |   6 ++
>  arch/loongarch/kernel/machine_kexec_file.c |   6 ++
>  arch/riscv/kernel/machine_kexec_file.c     |   4 +
>  drivers/of/fdt.c                           |  11 ++-
>  drivers/of/of_private.h                    |   3 +
>  drivers/of/of_reserved_mem.c               | 108 ++++++++++++++++++---
>  include/linux/crash_core.h                 |   6 ++
>  include/linux/of_reserved_mem.h            |  15 +++
>  kernel/dma/contiguous.c                    |   1 +
>  9 files changed, 142 insertions(+), 18 deletions(-)
>