Re: [PATCH v3 00/11] kdump: reduce vmcore size and capture time

[Baoquan He <baoquan.he@linux.dev>]

On 06/11/26 at 11:09am, Wandun wrote:
> 
> 
> On 6/11/26 10:09, Wandun wrote:
> > 
> > 
> > On 5/27/26 11:29, 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.
> >>
> >> The series is organized as follows:
> >> Patches 1-3: Pre-existing fixes and a small prep change.
> >> Patches 4-5: Restructure to allow appending /memreserve/ entries.
> >> Patches 6-7: Add a dumpable flag and append /memreserve/ entries.
> >> Patch 8: Add generic kdump helpers.
> >> Patches 9-11: Wire the helpers into arm64, riscv and loongarch kdump
> >>                elfcorehdr preparation.
> > Hi,
> > 
> > Gentle ping on this series.
> > 
> > Status summary:
> > -patch 03: respun separately per Rob's suggestion, picked up for 7.2
> > -patch 06: Acked-by: Marek Szyprowski -patch 09: Acked-by: Will Deacon
> > The remaining patches (01, 02, 04, 05, 07, 08, 10, 11) are still
> > awaiting review. your feedback would be greately appreciated. I know we
> > are at the end of 7.1 -rc cycle, I don't want to rush this series, just
> > collecting more feedback, and will send next version based on 7.2-rc1.
> > If spliting the series into smaller logical group would make review
> > easier, please let me know. Best regards, Wandun
> 
> Apologies for the formatting issue in my previous email.
> Here is the properly formatted version.
> 
> Gentle ping on this series.

Thanks for the effort, the overral looks good to me at 1st glance. I will
check if there's concern on generic part. And meanwhile, I am wondering
if there's any chance x86 or other ARCH-es w/o OF/FDT can also choose to
not dump some areas, e.g GPU stolen memory. Surely, that's another story.

> 
> Status summary:
> - patch 03: respun separately per Rob's suggestion, picked up for 7.2
> - patch 06: Acked-by: Marek Szyprowski
> - patch 09: Acked-by: Will Deacon
> 
> The remaining patches (01, 02, 04, 05, 07, 08, 10, 11) are still
> awaiting review. Your feedback would be greatly appreciated.
> 
> I know we are at the end of 7.1-rc cycle, I don't want to rush this
> series, just collecting more feedback, and will send next version based
> on 7.2-rc1.
> 
> If splitting the series into smaller logical groups would make review
> easier, please let me know.
> 
> Best regards,
> Wandun
> 
> 
> >>
> >> 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 (11):
> >>    of: reserved_mem: handle NULL name in of_reserved_mem_lookup()
> >>    kexec/crash: provide crash_exclude_mem_range() stub when
> >>      CONFIG_CRASH_DUMP=n
> >>    of: reserved_mem: avoid post-init UAF when alloc_reserved_mem_array()
> >>      fails
> >>    of: reserved_mem: zero total_reserved_mem_cnt if no valid
> >>      /reserved-memory entry
> >>    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               | 117 +++++++++++++++++++--
> >>   include/linux/crash_core.h                 |   6 ++
> >>   include/linux/of_reserved_mem.h            |  15 +++
> >>   kernel/dma/contiguous.c                    |   1 +
> >>   9 files changed, 157 insertions(+), 12 deletions(-)
> >>
> > 
>