Message-ID: <6c9b0aa2-820c-4153-ad64-cd2a45f7cf32@lucifer.local>
Date: Wed, 19 Nov 2025 16:30:27 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Eugen Hristev <eugen.hristev@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, tglx@...utronix.de, andersson@...nel.org,
        pmladek@...e.com, rdunlap@...radead.org, corbet@....net,
        david@...hat.com, mhocko@...e.com, tudor.ambarus@...aro.org,
        mukesh.ojha@....qualcomm.com, linux-arm-kernel@...ts.infradead.org,
        linux-hardening@...r.kernel.org, jonechou@...gle.com,
        rostedt@...dmis.org, linux-doc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-arch@...r.kernel.org, tony.luck@...el.com, kees@...nel.org
Subject: Re: [PATCH 00/26] Introduce meminspect

Hi Eugen,

You've not run scripts/get_maintainer.pl so this is missing a ton of maintainers
that you're required to send this to. This is not a great start for a huge 26
patch series that seems to want to make very significant changes.

Please try to follow proper kernel procedure.

Here's the list:

Jonathan Corbet <corbet@....net> (maintainer:DOCUMENTATION PROCESS)
Bjorn Andersson <andersson@...nel.org> (maintainer:REMOTE PROCESSOR (REMOTEPROC) SUBSYSTEM)
Mathieu Poirier <mathieu.poirier@...aro.org> (maintainer:REMOTE PROCESSOR (REMOTEPROC) SUBSYSTEM)
Konrad Dybcio <konradybcio@...nel.org> (maintainer:ARM/QUALCOMM SUPPORT)
Arnd Bergmann <arnd@...db.de> (maintainer:GENERIC INCLUDE/ASM HEADER FILES)
Mike Rapoport <rppt@...nel.org> (maintainer:MEMBLOCK AND MEMORY MANAGEMENT INITIALIZATION)
Thomas Gleixner <tglx@...utronix.de> (maintainer:CPU HOTPLUG)
Peter Zijlstra <peterz@...radead.org> (maintainer:CPU HOTPLUG,commit_signer:8/46=17%,removed_lines:4/63=6%)
Kees Cook <kees@...nel.org> (maintainer:EXEC & BINFMT API, ELF,commit_signer:7/46=15%)
Ingo Molnar <mingo@...hat.com> (maintainer:SCHEDULER,commit_signer:1/2=50%)
Juri Lelli <juri.lelli@...hat.com> (maintainer:SCHEDULER)
Vincent Guittot <vincent.guittot@...aro.org> (maintainer:SCHEDULER)
Dietmar Eggemann <dietmar.eggemann@....com> (reviewer:SCHEDULER)
Steven Rostedt <rostedt@...dmis.org> (reviewer:SCHEDULER)
Ben Segall <bsegall@...gle.com> (reviewer:SCHEDULER)
Mel Gorman <mgorman@...e.de> (reviewer:SCHEDULER)
Valentin Schneider <vschneid@...hat.com> (reviewer:SCHEDULER)
Andrew Morton <akpm@...ux-foundation.org> (maintainer:MEMORY MANAGEMENT - CORE,commit_signer:5/46=11%,commit_signer:14/22=64%)
David Hildenbrand <david@...nel.org> (maintainer:MEMORY MANAGEMENT - CORE)
Lorenzo Stoakes <lorenzo.stoakes@...cle.com> (reviewer:MEMORY MANAGEMENT - CORE)
"Liam R. Howlett" <Liam.Howlett@...cle.com> (reviewer:MEMORY MANAGEMENT - CORE)
Vlastimil Babka <vbabka@...e.cz> (reviewer:MEMORY MANAGEMENT - CORE)
Suren Baghdasaryan <surenb@...gle.com> (reviewer:MEMORY MANAGEMENT - CORE)
Michal Hocko <mhocko@...e.com> (reviewer:MEMORY MANAGEMENT - CORE)
Petr Mladek <pmladek@...e.com> (maintainer:PRINTK,commit_signer:5/22=23%)
John Ogness <john.ogness@...utronix.de> (reviewer:PRINTK)
Sergey Senozhatsky <senozhatsky@...omium.org> (reviewer:PRINTK,added_lines:21/262=8%,removed_lines:9/89=10%)
Anna-Maria Behnsen <anna-maria@...utronix.de> (maintainer:HIGH-RESOLUTION TIMERS, TIMER WHEEL, CLOCKEVENTS)
Frederic Weisbecker <frederic@...nel.org> (maintainer:HIGH-RESOLUTION TIMERS, TIMER WHEEL, CLOCKEVENTS)
Brendan Jackman <jackmanb@...gle.com> (reviewer:MEMORY MANAGEMENT - PAGE ALLOCATOR)
Johannes Weiner <hannes@...xchg.org> (reviewer:MEMORY MANAGEMENT - PAGE ALLOCATOR)
Zi Yan <ziy@...dia.com> (reviewer:MEMORY MANAGEMENT - PAGE ALLOCATOR)
Dennis Zhou <dennis@...nel.org> (maintainer:PER-CPU MEMORY ALLOCATOR)
Tejun Heo <tj@...nel.org> (maintainer:PER-CPU MEMORY ALLOCATOR)
Christoph Lameter <cl@...two.org> (maintainer:PER-CPU MEMORY ALLOCATOR)
Chris Li <chrisl@...nel.org> (maintainer:MEMORY MANAGEMENT - SWAP)
Kairui Song <kasong@...cent.com> (maintainer:MEMORY MANAGEMENT - SWAP)
Kemeng Shi <shikemeng@...weicloud.com> (reviewer:MEMORY MANAGEMENT - SWAP)
Nhat Pham <nphamcs@...il.com> (reviewer:MEMORY MANAGEMENT - SWAP)
Baoquan He <bhe@...hat.com> (reviewer:MEMORY MANAGEMENT - SWAP)
Barry Song <baohua@...nel.org> (reviewer:MEMORY MANAGEMENT - SWAP)
"Thomas Weißschuh" <thomas.weissschuh@...utronix.de> (added_lines:13/207=6%)
workflows@...r.kernel.org (open list:DOCUMENTATION PROCESS)
linux-doc@...r.kernel.org (open list:DOCUMENTATION)
linux-kernel@...r.kernel.org (open list)
linux-arm-msm@...r.kernel.org (open list:ARM/QUALCOMM MAILING LIST)
linux-remoteproc@...r.kernel.org (open list:REMOTE PROCESSOR (REMOTEPROC) SUBSYSTEM)
linux-arch@...r.kernel.org (open list:GENERIC INCLUDE/ASM HEADER FILES)
linux-mm@...ck.org (open list:MEMBLOCK AND MEMORY MANAGEMENT INITIALIZATION)

On Wed, Nov 19, 2025 at 05:44:01PM +0200, Eugen Hristev wrote:
> meminspect is a mechanism which allows the kernel to mark specific memory
> areas for memory dumping or specific inspection, statistics, usage.
> Once regions are marked, meminspect keeps an internal list with the regions
> in a dedicated table.
> Further, these regions can be accessed using specific API by any interested driver.

Instincitivley not a great fan of exposing and manipulating memory resources to
drives in such a way but I haven't looked into this in detail here.

> Regions being marked beforehand, when the system is up and running, there
> is no need nor dependency on a panic handler, or a working kernel that can
> dump the debug information.
> meminspect can be primarily used for debugging. The approach is feasible to work
> when pstore, kdump, or another mechanism do not.
> Pstore relies on persistent storage, a dedicated RAM area or flash, which
> has the disadvantage of having the memory reserved all the time, or another
> specific non volatile memory. Some devices cannot keep the RAM contents on
> reboot so ramoops does not work. Some devices do not allow kexec to run
> another kernel to debug the crashed one.
> For such devices, that have another mechanism to help debugging, like
> firmware, kmemdump is a viable solution.
>
> meminspect can create a core image, similar with /proc/vmcore, with only
> the registered regions included. This can be loaded into crash tool/gdb and
> analyzed. This happens if CRASH_DUMP=y.
> To have this working, specific information from the kernel is registered,
> and this is done at meminspect init time, no need for the meminspect users to
> do anything.
>
> This version of the meminspect patch series includes two drivers that make use of it:
> one is the Qualcomm Minidump, and the other one is the Debug Kinfo
> backend for Android devices, reworked from this source here:
> https://android.googlesource.com/kernel/common/+/refs/heads/android-mainline/drivers/android/debug_kinfo.c
> written originally by Jone Chou <jonechou@...gle.com>
>
> *** History, motivation and available online resources ***
>
> The patch series is based on both minidump and kmemdump previous implementations.
>
> After the three RFC kmemdump versions, considering the ML discussions, I decided to
> move this into kernel/ directory and rework it into naming it meminspect, as Thomas Gleixner
> suggested.
> I will present this version at Plumbers conference in Tokyo on December 13th:
> https://lpc.events/event/19/contributions/2080/
> I am eager to discuss it there face to face.
>
> Initial version of kmemdump and discussion is available here:
> https://lore.kernel.org/lkml/20250422113156.575971-1-eugen.hristev@linaro.org/
>
> Kmemdump has been presented and discussed at Linaro Connect 2025,
> including motivation, scope, usability and feasability.
> Video of the recording is available here for anyone interested:
> https://www.youtube.com/watch?v=r4gII7MX9zQ&list=PLKZSArYQptsODycGiE0XZdVovzAwYNwtK&index=14
>
> Linaro blog on kmemdump can be found here:
> https://www.linaro.org/blog/introduction-to-kmemdump/
>
> Linaro blog on kmemdump step by stem using minidump backend is available here:
> https://www.linaro.org/blog/kmemdump-step-by-step-on-qualcomm-automotive-platform/
>
> The implementation is based on the initial Pstore/directly mapped zones
> published as an RFC here:
> https://lore.kernel.org/all/20250217101706.2104498-1-eugen.hristev@linaro.org/
>
> The back-end implementation for qcom_minidump is based on the minidump
> patch series and driver written by Mukesh Ojha, thanks:
> https://lore.kernel.org/lkml/20240131110837.14218-1-quic_mojha@quicinc.com/
>
> The RFC v2 version with .section creation and macro annotation kmemdump
> is available here:
> https://lore.kernel.org/all/20250724135512.518487-1-eugen.hristev@linaro.org/
>
> The RFC v3 version with making everything static, which was pretty much rejected due to
> all reasons discussed on the public ML:
> https://lore.kernel.org/all/20250912150855.2901211-1-eugen.hristev@linaro.org/

OK so you've sent several RFC's and not cc'd the right people in any of them :/

This isn't great kernel etiquette.

>
> *** How to use meminspect with minidump backend on Qualcomm platform guide ***
>
> Prerequisites:
> Crash tool compiled with target=ARM64 and minor changes required for usual crash
> mode (minimal mode works without the patch)
> **A patch can be applied from here https://p.calebs.dev/1687bc **
> This patch will be eventually sent in a reworked way to crash tool.
>
> Target kernel must be built with :
> CONFIG_DEBUG_INFO_REDUCED=n ; this will have vmlinux include all the debugging
> information needed for crash tool.
>
> Also, the kernel requires these as well:
> CONFIG_MEMINSPECT,  CONFIG_CRASH_DUMP and the driver CONFIG_QCOM_MINIDUMP
>
> Kernel arguments:
> Kernel firmware must be set to mode 'mini' by kernel module parameter
> like this : qcom_scm.download_mode=mini
>
> After the kernel boots, and minidump module is loaded, everything is ready for
> a possible crash.
>
> Once the crash happens, the firmware will kick in and you will see on
> the console the message saying Sahara init, etc, that the firmware is
> waiting in download mode. (this is subject to firmware supporting this
> mode, I am using sa8775p-ride board)
>
> Example of log on the console:
> "
> [...]
> B -   1096414 - usb: init start
> B -   1100287 - usb: qusb_dci_platform , 0x19
> B -   1105686 - usb: usb3phy: PRIM success: lane_A , 0x60
> B -   1107455 - usb: usb2phy: PRIM success , 0x4
> B -   1112670 - usb: dci, chgr_type_det_err
> B -   1117154 - usb: ID:0x260, value: 0x4
> B -   1121942 - usb: ID:0x108, value: 0x1d90
> B -   1124992 - usb: timer_start , 0x4c4b40
> B -   1129140 - usb: vbus_det_pm_unavail
> B -   1133136 - usb: ID:0x252, value: 0x4
> B -   1148874 - usb: SUPER , 0x900e
> B -   1275510 - usb: SUPER , 0x900e
> B -   1388970 - usb: ID:0x20d, value: 0x0
> B -   1411113 - usb: ENUM success
> B -   1411113 - Sahara Init
> B -   1414285 - Sahara Open
> "
>
> Once the board is in download mode, you can use the qdl tool (I
> personally use edl , have not tried qdl yet), to get all the regions as
> separate files.
> The tool from the host computer will list the regions in the order they
> were downloaded.
>
> Once you have all the files simply use `cat` to put them all together,
> in the order of the indexes.
> For my kernel config and setup, here is my cat command : (you can use a script
> or something, I haven't done that so far):
>
> `cat memory/md_KELF1.BIN memory/md_Kvmcorein2.BIN memory/md_Kconfig3.BIN \
> memory/md_Ktotalram4.BIN memory/md_Kcpu_poss5.BIN memory/md_Kcpu_pres6.BIN \
> memory/md_Kcpu_onli7.BIN memory/md_Kcpu_acti8.BIN memory/md_Kmem_sect9.BIN \
> memory/md_Kjiffies10.BIN memory/md_Klinux_ba11.BIN memory/md_Knr_threa12.BIN \
> memory/md_Knr_irqs13.BIN memory/md_Ktainted_14.BIN memory/md_Ktaint_fl15.BIN \
> memory/md_Knode_sta16.BIN memory/md_K__per_cp17.BIN memory/md_Knr_swapf18.BIN \
> memory/md_Kinit_uts19.BIN memory/md_Kprintk_r20.BIN memory/md_Kprintk_r21.BIN \
> memory/md_Kprb22.BIN memory/md_Kprb_desc23.BIN memory/md_Kprb_info24.BIN \
> memory/md_Kprb_data25.BIN  memory/md_Khigh_mem26.BIN memory/md_Kinit_mm27.BIN \
> memory/md_Kunknown29.BIN memory/md_Kunknown30.BIN memory/md_Kunknown31.BIN \
> memory/md_Kunknown32.BIN memory/md_Kunknown33.BIN memory/md_Kunknown34.BIN \
> memory/md_Kunknown35.BIN memory/md_Kunknown36.BIN memory/md_Kunknown37.BIN \
> memory/md_Kunknown38.BIN memory/md_Kunknown39.BIN memory/md_Kunknown40.BIN \
> memory/md_Kunknown41.BIN memory/md_Kunknown42.BIN memory/md_Kunknown43.BIN \
> memory/md_Kunknown44.BIN memory/md_Kunknown45.BIN  memory/md_Kunknown46.BIN \
> memory/md_Kunknown47.BIN memory/md_Kunknown48.BIN memory/md_Kunknown49.BIN \
> memory/md_Kunknown50.BIN memory/md_Kunknown51.BIN memory/md_Kunknown52.BIN \
> memory/md_Kunknown53.BIN memory/md_Kunknown54.BIN memory/md_Kunknown55.BIN \
> memory/md_Kunknown56.BIN memory/md_Kunknown57.BIN > ~/minidump_image`
>
> Once you have the resulted file, use `crash` tool to load it, like this:
> `./crash --no_modules --no_panic --no_kmem_cache --zero_excluded vmlinux minidump_image`
>
> There is also a --minimal mode for ./crash that would work without any patch applied
> to crash tool, but you can't inspect symbols, etc.
>
> Once you load crash you will see something like this :
>       KERNEL: /home/eugen/linux-minidump/vmlinux  [TAINTED]
>     DUMPFILE: /home/eugen/a
>         CPUS: 8 [OFFLINE: 6]
>         DATE: Thu Jan  1 02:00:00 EET 1970
>       UPTIME: 00:00:25
>        TASKS: 0
>     NODENAME: qemuarm64
>      RELEASE: 6.18.0-rc2-00030-g65df2b8a0dde
>      VERSION: #33 SMP PREEMPT Mon Nov 17 13:30:54 EET 2025
>      MACHINE: aarch64  (unknown Mhz)
>       MEMORY: 0
>        PANIC: ""
> crash> log
> [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd4b2]
> [    0.000000] Linux version 6.18.0-rc2-00030-g65df2b8a0dde
>
> *** Debug Kinfo backend driver ***
> I don't have any device to actually test this. So I have not.
> I hacked the driver to just use a kmalloc'ed area to save things instead
> of the shared memory, and dumped everything there and checked whether it is identical
> with what the downstream driver would have saved.
> So this synthetic test passed and memories are identical.
> Anyone who actually wants to test this, feel free to reply to the patch.
> I have also written a simple DT binding for the driver.
>
> Thanks for everyone reviewing and bringing ideas into the discussion.
>
> Eugen
>
> Changelog for meminspect v1:
> - rename to meminspect
> - start on top of v2 actually, with the section and all.
> - remove the backend thing, change the API to access the table
> - move everything to kernel/
> - add dependency to CRASH_DUMP instead of a separate knob
> - move the minidump driver to soc/qcom
> - integrate the meminspect better into memblock by using a new memblock flag
> - minor fixes : use dev_err_probe everywhere, rearrange variable declarations,
> remove some useless code, etc.
>
> Changelog for RFC v3:
> - V2 available here : https://lore.kernel.org/all/20250724135512.518487-1-eugen.hristev@linaro.org/
> - Removed the .section as requested by David Hildenbrand.
> - Moved all kmemdump registration(when possible) to vmcoreinfo.
> - Because of this, some of the variables that I was registering had to be non-static
> so I had to modify this as per David Hildenbrand suggestion.
> - Fixed minor things in the Kinfo driver: one field was broken, fixed some
> compiler warnings, fixed the copyright and remove some useless includes.
> - Moved the whole kmemdump from drivers/debug into mm/ and Kconfigs into mm/Kconfig.debug
> and it's now available in kernel hacking, as per Randy Dunlap review
> - Reworked some of the Documentation as per review from Jon Corbet
>
>
> Changelog for RFC v2:
> - V1 available here: https://lore.kernel.org/lkml/20250422113156.575971-1-eugen.hristev@linaro.org/
> - Reworked the whole minidump implementation based on suggestions from Thomas Gleixner.
> This means new API, macros, new way to store the regions inside kmemdump
> (ditched the IDR, moved to static allocation, have a static default backend, etc)
> - Reworked qcom_minidump driver based on review from Bjorn Andersson
> - Reworked printk log buffer registration based on review from Petr Mladek
>
> I appologize if I missed any review comments.
> Patches are sent on top on 6.18-rc2
>
> Eugen Hristev (26):
>   kernel: Introduce meminspect
>   init/version: Annotate static information into meminspect
>   mm/percpu: Annotate static information into meminspect
>   cpu: Annotate static information into meminspect
>   genirq/irqdesc: Annotate static information into meminspect
>   timers: Annotate static information into meminspect
>   kernel/fork: Annotate static information into meminspect
>   mm/page_alloc: Annotate static information into meminspect
>   mm/show_mem: Annotate static information into meminspect
>   mm/swapfile: Annotate static information into meminspect
>   kernel/vmcore_info: Register dynamic information into meminspect
>   kernel/configs: Register dynamic information into meminspect
>   mm/init-mm: Annotate static information into meminspect
>   panic: Annotate static information into meminspect
>   kallsyms: Annotate static information into meminspect
>   mm/mm_init: Annotate static information into meminspect
>   sched/core: Annotate runqueues into meminspect
>   mm/memblock: Add MEMBLOCK_INSPECT flag
>   mm/numa: Register information into meminspect
>   mm/sparse: Register information into meminspect
>   printk: Register information into meminspect
>   remoteproc: qcom: Extract minidump definitions into a header
>   soc: qcom: Add minidump driver
>   soc: qcom: smem: Add minidump device
>   dt-bindings: reserved-memory: Add Google Kinfo Pixel reserved memory
>   meminspect: Add Kinfo compatible driver
>
>  Documentation/dev-tools/index.rst             |   1 +
>  Documentation/dev-tools/meminspect.rst        | 139 ++++++
>  .../reserved-memory/google,kinfo.yaml         |  49 ++
>  MAINTAINERS                                   |  13 +
>  drivers/remoteproc/qcom_common.c              |  56 +--
>  drivers/soc/qcom/Kconfig                      |  13 +
>  drivers/soc/qcom/Makefile                     |   1 +
>  drivers/soc/qcom/minidump.c                   | 272 ++++++++++
>  drivers/soc/qcom/smem.c                       |  10 +
>  include/asm-generic/vmlinux.lds.h             |  13 +
>  include/linux/memblock.h                      |   7 +
>  include/linux/meminspect.h                    | 261 ++++++++++
>  include/linux/soc/qcom/minidump.h             |  72 +++
>  init/Kconfig                                  |   2 +
>  init/version-timestamp.c                      |   3 +
>  init/version.c                                |   3 +
>  kernel/Makefile                               |   1 +
>  kernel/configs.c                              |   6 +
>  kernel/cpu.c                                  |   5 +
>  kernel/fork.c                                 |   2 +
>  kernel/irq/irqdesc.c                          |   2 +
>  kernel/kallsyms.c                             |  10 +
>  kernel/meminspect/Kconfig                     |  30 ++
>  kernel/meminspect/Makefile                    |   4 +
>  kernel/meminspect/kinfo.c                     | 289 +++++++++++
>  kernel/meminspect/meminspect.c                | 470 ++++++++++++++++++
>  kernel/panic.c                                |   4 +
>  kernel/printk/printk.c                        |  12 +
>  kernel/sched/core.c                           |   2 +
>  kernel/time/timer.c                           |   2 +
>  kernel/vmcore_info.c                          |   4 +
>  mm/init-mm.c                                  |  11 +
>  mm/memblock.c                                 |  36 ++
>  mm/mm_init.c                                  |   2 +
>  mm/numa.c                                     |   2 +
>  mm/page_alloc.c                               |   2 +
>  mm/percpu.c                                   |   2 +
>  mm/show_mem.c                                 |   2 +
>  mm/sparse.c                                   |   4 +
>  mm/swapfile.c                                 |   2 +
>  40 files changed, 1766 insertions(+), 55 deletions(-)
>  create mode 100644 Documentation/dev-tools/meminspect.rst
>  create mode 100644 Documentation/devicetree/bindings/reserved-memory/google,kinfo.yaml
>  create mode 100644 drivers/soc/qcom/minidump.c
>  create mode 100644 include/linux/meminspect.h
>  create mode 100644 include/linux/soc/qcom/minidump.h
>  create mode 100644 kernel/meminspect/Kconfig
>  create mode 100644 kernel/meminspect/Makefile
>  create mode 100644 kernel/meminspect/kinfo.c
>  create mode 100644 kernel/meminspect/meminspect.c
>
> --
> 2.43.0
>
>
>

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