Hi Kazu, On Mon, Jun 22, 2026 at 5:57 PM HAGIO KAZUHITO(萩尾 一仁) <[email protected]> wrote: > > Hi Tao, > > I've tested some, no issue was detected. > > [without the patchset] > 8.09user 1.01system 0:10.04elapsed 90%CPU (0avgtext+0avgdata 4480maxresident)k > 18672inputs+763736outputs (0major+268minor)pagefaults 0swaps > > [with the patchset without --extension] > 8.08user 0.99system 0:09.94elapsed 91%CPU (0avgtext+0avgdata > 4608maxresident)k # +128k > 19640inputs+763720outputs (4major+277minor)pagefaults 0swaps > > [with the patchset with --extension] > 6.38user 0.74system 0:07.92elapsed 89%CPU (0avgtext+0avgdata > 16984maxresident)k # +12M > 17048inputs+725240outputs (0major+3121minor)pagefaults 0swaps > > There is also no noticeable rise in max rss without --extension. > > Maybe support for compound pages can be debatable in the future, but > I think the current patchset is good enough for extension v1. > So merged 01/10 - 09/10 patches, thank you for the great work!
Thanks for your testing, also many thanks for your code review and suggestions! Thanks, Tao Liu > > Thanks, > Kazu > > > > On 2026/06/17 14:18, Tao Liu wrote: > > A) This patchset will introduce the following features to makedumpfile: > > > > 1) Add .so extension support to makedumpfile > > 2) Enable btf and kallsyms for symbol type and address resolving. > > > > B) The purpose of the features are: > > > > 1) Currently makedumpfile filters mm pages based on page flags, because > > flags > > can help to determine one page's usage. But this page-flag-checking > > method > > lacks of flexibility in certain cases, e.g. if we want to filter > > those mm > > pages occupied by GPU during vmcore dumping due to: > > > > a) GPU may be taking a large memory and contains sensitive data; > > b) GPU mm pages have no relations to kernel crash and useless for > > vmcore > > analysis. > > > > But there is no GPU mm page specific flags, and apparently we don't > > need > > to create one just for kdump use. A programmable filtering tool is > > more > > suitable for such cases. In addition, different GPU vendors may use > > different ways for mm pages allocating, programmable filtering is > > better > > than hard coding these GPU specific logics into makedumpfile in this > > case. > > > > 2) Currently makedumpfile already contains a programmable filtering > > tool, aka > > eppic script, which allows user to write customized code for data > > erasing. > > However it has the following drawbacks: > > > > a) cannot do mm page filtering. > > b) need to access to debuginfo of both kernel and modules, which is > > not > > applicable in the 2nd kernel. > > c) eppic library has memory leaks which are not all resolved [1]. This > > is not acceptable in 2nd kernel. > > > > makedumpfile need to resolve the dwarf data from debuginfo, to get > > symbols > > types and addresses. In recent kernel there are dwarf alternatives > > such > > as btf/kallsyms which can be used for this purpose. And btf/kallsyms > > info > > are already packed within vmcore, so we can use it directly. > > > > With these, this patchset introduces makedumpfile extensions, which is > > based > > on btf/kallsyms symbol resolving, and is programmable for mm page > > filtering. > > The following section shows its usage and performance, please note the > > tests > > are performed in 1st kernel. > > > > 3) Compile and run makedumpfile extensions: > > > > $ make LINKTYPE=dynamic USELZO=on USESNAPPY=on USEZSTD=on EXTENSION=on > > $ make extensions > > > > $ /usr/bin/time -v ./makedumpfile -d 31 -l > > /var/crash/127.0.0.1-2025-06-10-18\:03\:12/vmcore > > /tmp/extension.out --extension amdgpu_filter.so > > Loaded extension: ./extensions/amdgpu_filter.so > > makedumpfile Completed. > > User time (seconds): 5.08 > > System time (seconds): 0.84 > > Percent of CPU this job got: 99% > > Elapsed (wall clock) time (h:mm:ss or m:ss): 0:05.95 > > Maximum resident set size (kbytes): 17360 > > ... > > > > To contrast with eppic script of v2 [2]: > > > > $ /usr/bin/time -v ./makedumpfile -d 31 -l > > /var/crash/127.0.0.1-2025-06-10-18\:03\:12/vmcore > > /tmp/eppic.out --eppic eppic_scripts/filter_amdgpu_mm_pages.c > > makedumpfile Completed. > > User time (seconds): 8.23 > > System time (seconds): 0.88 > > Elapsed (wall clock) time (h:mm:ss or m:ss): 0:09.16 > > Maximum resident set size (kbytes): 57128 > > ... > > > > -rw------- 1 root root 367475074 Jan 19 19:01 /tmp/extension.out > > -rw------- 1 root root 367475074 Jan 19 19:48 /tmp/eppic.out > > -rw------- 1 root root 387181418 Jun 10 18:03 > > /var/crash/127.0.0.1-2025-06-10-18:03:12/vmcore > > > > C) Discussion: > > > > 1) GPU types: Currently only tested with amdgpu's mm page filtering, > > others > > are not tested. > > 2) OS: The code can work on rhel-10+/rhel9.5+ on x86_64/arm64/s390/ppc64. > > rhel8.x is not supported, others are not tested. > > > > D) Testing: > > > > If you don't want to create your vmcore, you can find a vmcore which I > > created with amdgpu mm pages unfiltered [3], the amdgpu mm pages are > > allocated by program [4]. You can use the vmcore in 1st kernel to > > filter > > the amdgpu mm pages by the previous performance testing cmdline. To > > verify the pages are filtered in crash: > > > > Unfiltered: > > crash> search -c "!QAZXSW@#EDC" > > ffff96b7fa800000: > > !QAZXSW@#EDCXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > ffff96b87c800000: > > !QAZXSW@#EDCXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX > > crash> rd ffff96b7fa800000 > > ffff96b7fa800000: 405753585a415121 !QAZXSW@ > > crash> rd ffff96b87c800000 > > ffff96b87c800000: 405753585a415121 !QAZXSW@ > > > > Filtered: > > crash> search -c "!QAZXSW@#EDC" > > crash> rd ffff96b7fa800000 > > rd: page excluded: kernel virtual address: ffff96b7fa800000 type: > > "64-bit KVADDR" > > crash> rd ffff96b87c800000 > > rd: page excluded: kernel virtual address: ffff96b87c800000 type: > > "64-bit KVADDR" > > > > [1]: https://github.com/lucchouina/eppic/pull/32 > > [2]: https://lore.kernel.org/kexec/[email protected]/ > > [3]: https://people.redhat.com/~ltao/core/vmcore > > [4]: https://gist.github.com/liutgnu/a8cbce1c666452f1530e1410d1f352df > > > > v6 -> v5: > > > > 1) Add erase_sample extension for data erasure sample. > > 2) Replace fprintf() to MSG()/ERRMSG() in kallsyms.h. > > 3) Use handle_cbs_len in extension_has_callback() for callback check. > > 4) Fix bug[5]. > > 5) Add handle_cbs[i]->cb = NULL in init_extensions() to reset the > > callback if one extension's init() is skipped. > > 6) The patches are organized as follows: > > > > ---- <customization specific> --- > > 10. Add amdgpu mm pages filtering extension > > > > --- <code should be merged> --- > > 9. Doc: Add --extension option to makedumpfile manual > > 8. Add erase_sample extension as an data erase reference > > 7. Add sample extension as an example reference > > 6. Add makedumpfile extensions support > > 5. Implement kernel module's btf resolving > > 4. Implement kernel module's kallsyms resolving > > 3. Implement kernel btf resolving > > 2. Implement kernel kallsyms resolving > > 1. Reserve sections for makedumpfile and extenions > > > > Patch 10 is customization specific, merging depends on the strategy of > > maintenance. > > Patch 1 ~ 9 are common code which should be merged with makedumpfile. > > > > [5]: > > https://lore.kernel.org/kexec/[email protected]/ > > > > Link to v5: > > https://lore.kernel.org/kexec/[email protected]/ > > Link to v4: > > https://lore.kernel.org/kexec/[email protected]/ > > Link to v3: > > https://lore.kernel.org/kexec/[email protected]/ > > Link to v2: > > https://lore.kernel.org/kexec/[email protected]/ > > Link to v1: > > https://lore.kernel.org/kexec/[email protected]/ > > > > Tao Liu (10): > > Reserve sections for makedumpfile and extenions > > Implement kernel kallsyms resolving > > Implement kernel btf resolving > > Implement kernel module's kallsyms resolving > > Implement kernel module's btf resolving > > Add makedumpfile extensions support > > Add sample extension as an example reference > > Add erase_sample extension as an data erase reference > > Doc: Add --extension option to makedumpfile manual > > Add amdgpu mm pages filtering extension > > > > Makefile | 15 +- > > README | 6 + > > btf_info.c | 371 +++++++++++++++++++++++++ > > btf_info.h | 77 ++++++ > > extension.c | 355 ++++++++++++++++++++++++ > > extension.h | 16 ++ > > extensions/Makefile | 13 + > > extensions/amdgpu_filter.c | 221 +++++++++++++++ > > extensions/erase_sample.c | 78 ++++++ > > extensions/maple_tree.c | 328 ++++++++++++++++++++++ > > extensions/maple_tree.h | 7 + > > extensions/sample.c | 69 +++++ > > kallsyms.c | 550 +++++++++++++++++++++++++++++++++++++ > > kallsyms.h | 86 ++++++ > > makedumpfile.8.in | 11 +- > > makedumpfile.c | 44 ++- > > makedumpfile.h | 12 + > > makedumpfile.ld | 16 ++ > > 18 files changed, 2266 insertions(+), 9 deletions(-) > > create mode 100644 btf_info.c > > create mode 100644 btf_info.h > > create mode 100644 extension.c > > create mode 100644 extension.h > > create mode 100644 extensions/Makefile > > create mode 100644 extensions/amdgpu_filter.c > > create mode 100644 extensions/erase_sample.c > > create mode 100644 extensions/maple_tree.c > > create mode 100644 extensions/maple_tree.h > > create mode 100644 extensions/sample.c > > create mode 100644 kallsyms.c > > create mode 100644 kallsyms.h > > create mode 100644 makedumpfile.ld > >
