This is also posted to the mailing list.
Hello community,
This newsletter covers DAMON features that landed on or queued for the mainline, development statistics and misc events that were noteworthy in my opinion, that were happened from v7.3-rc1 (2026-08-30) to v7.4-rc1 (2026-11-01) time period.
The newsletter covering the previous release cycle (v7.2-rc1..v7.3-rc1) is also available [1].
TL;DR
23 authors made 159 commits with 3,260 lines of changes for DAMON on the Linux mainline. 7 new features are landed with important optimizations and fixes. It was another busiest cycle in DAMON history, in terms of the number of authors, the number of merge window commits and mail traffic. Nonetheless, the speed of the growth of the number in recent cycles started reducing.
Changes Landed on 7.3
All 146 commits that were landed on v7.3-rc1 have successfully landed on v7.3. In addition to those, 7 additional hotfixes have merged into 7.3.
Those from 7.3-rc1 include a few user-visible and impactful features and optimizations. To pick only two among those, data attributes-only monitoring feature (commit 37aae41c1056) and pseudo moving probe_hits sum optimization (commit aa497a270f68) are introduced. Those make DAMON extending to work from only data access to general data attributes more complete. Read the previous newsletter [1] for more details.
Changes Landed for 7.4
During the 7.3-rc1 merge window, 152 DAMON patches have landed via the MM pull requests [2,3]. Introducing a few of changes that could introduce non-trivial impacts.
New Features
In this merge window, below seven new features are added.
- Commit f465dc71aba0: Patch series “mm/damon: Introduce a huge page collapsing mechanism using auto tuning”, v4.
- Commit f138b7b98ec5: Patch series “mm/damon: introduce data access-as-a-data attribute”, v1.1.
- Commit df8060e66580: Patch series “mm/damon/vaddr: support {prep,apply}_probes”.
- Commit f8facff65cb3: Patch series “mm/damon: introduce pgidle_set probe filter type”.
- Commit 724468135d75: Patch series “mm/damon: introduce probe_hits_wsum DAMOS core filter”, v2.
- Commit 222636c8c139: Patch series “mm/damon: introduce hugepage_size probe filter”.
- Commit de6632aa7851: Patch series “mm/damon: introduce damos quota goal target metric complement flag”.
The first feature is contributed by Asier Gutierrez from Huawei. It allows DAMOS automatically collapsing huge pages to make no more, no less but a specific portion of system memory be backed by huge pages, to get huge page benefit while controlling the amount of internal fragmentation.
The next five features are all for data attributes extension. Second feature makes data access monitoring can be replaced by data attributes monitoring. Third feature adds virtual address support for the attributes monitoring. Fourth feature makes attributes monitoring more useful for cold and actionable memory detection. Fifth feature allows data attributes based DAMOS. Sixth feature extends attributes monitoring for another attribute, hugepage-ness.
The seventh feature makes DAMOS quota goal to be easily customizable for more flexible use cases.
Optimizations
Below important optimization is added in this merge window.
- Commit 3453f37fed8e: Patch series “mm/damon: support access monitoring of hugetlb-backed memory”, v3.
DAMON was not supporting monitoring of accesses on hugetlb-backed memory. Krishna Iyer from Crusoe found this is making their access pattern monitoring on their setup difficult. Krishna further developed and contributed this huge optimization that allows DAMON monitoring hugetlb memory.
Refactoring and Bug Fixes
Quite a number of changes in the 7.4-rc1 merge window were for fixing DAMON bugs and refactoring code to be more tolerant to future bugs. Because the changes are quite spread around, not listing most of the commits here.
While most fixed bugs were minor ones, below fix was for a nasty and impactful bug that is noteworthy.
- Commit f166586f74dd: “mm/damon/ops-common: use a page-aligned address in damon_ptep_mkold()”
The bug causes difficult-to-debug memory corruption on arm64. It was found and fixed by Nathan Gao from AWS. Nathan found it from their Amazon Linux 2027 preview works.
Changes Cooking for >7.4
A number of patches are queued and being developed for future mainline landing. Three hotfixes are queued in mm.git. My personal tree for those (damon/next) contains 142 downstream patches as of this writing. Not all the patches are ready to, or intended to be merged in near future. Some will be squashed or broken down. Anyway, the number was 214 for the last release cycle. This cycle is likely to be less busier than the last cycle.
Statistics
Putting simple statistics for the last release period. Tools other than git that are used here for getting the numbers are available [4,5] at GitHub.
In short, while the amount of hotfixes in the non-merge window decreased, the number of changes for the merge window broke the record. In terms of total number of commits, though, the continued trend of the increase has stopped.
Number of Hotfixes and Non-hotfixes
7 DAMON hotfixes have landed on 7.3.
git -C ./ log v7.3-rc1..v7.3 --oneline --no-merges -- \
Documentation/ABI/testing/sysfs-kernel-mm-damon \
Documentation/admin-guide/mm/damon/ Documentation/mm/damon/ \
Documentation/vm/damon/ include/linux/damon.h \
include/trace/events/damon.h mm/damon/ samples/damon/ \
tools/testing/selftests/damon | wc -l
7
152 DAMON changes have landed on 7.4-rc1 during the merge window.
git -C ./ log v7.3..v7.4-rc1 --oneline --no-merges -- \
Documentation/ABI/testing/sysfs-kernel-mm-damon \
Documentation/admin-guide/mm/damon/ Documentation/mm/damon/ \
Documentation/vm/damon/ include/linux/damon.h \
include/trace/events/damon.h mm/damon/ samples/damon/ \
tools/testing/selftests/damon | wc -l
152
The numbers for the last ten release cycles are like below:
7.3 fixes: 7 7.4 changes:0 total:159
7.2 fixes: 15 7.3 changes:0 total:161
7.1 fixes: 11 7.2 changes:0 total:106
7.0 fixes: 9 7.1 changes:0 total:73
6.19 fixes: 7 7.0 changes:0 total:75
6.18 fixes: 7 6.19 changes:0 total:85
6.17 fixes: 15 6.18 changes:0 total:56
6.16 fixes: 8 6.17 changes:0 total:101
6.15 fixes: 0 6.16 changes:0 total:22
6.14 fixes: 6 6.15 changes:0 total:68
Since 7.1 development cycle, DAMON development was only getting busier for every cycle in terms of the total number of commits. 7.4 development cycle stopped the trend. It was mainly due to the decreased number of hotfixes that merged after the merge window. In terms of the merge window only changes, it broke the record again. But, obviously the speed of the growth of the number is reduced.
Authors, Commits and Changed Lines
In this cycle, 23 people made grateful 159 commits with 3260 lines of changes for DAMON on the Linux mainline.
$ # stat for number of commits
$ ./lazybox/version_control/authors.py ./linux/ \
--since v7.3-rc1 --until v7.4-rc1 \
--skip_merge_commits --linux_subsystems DAMON
1. SJ Park <sj@kernel.org>: 111 commits
2. Liew Rui Yan <aethernet65535@gmail.com>: 9 commits
3. Zenghui Yu (Huawei) <zenghui.yu@linux.dev>: 5 commits
4. Karl Mehltretter <kmehltretter@gmail.com>: 4 commits
5. Donggeun Yoo <donggeunyoo.kernel@gmail.com>: 4 commits
6. Krishna Iyer <kiyer@crusoe.ai>: 3 commits
7. Asier Gutierrez <gutierrez.asier@huawei-partners.com>: 3 commits
8. Jaeyeon Lee <jaeyeon.lee.dev@gmail.com>: 2 commits
9. Enze Li <lienze@kylinos.cn>: 2 commits
10. Cheng-Han Wu <hank20010209@gmail.com>: 2 commits
11. Jason Angelov <jasonangelov@ucla.edu>: 2 commits
12. Gregory Price <gourry@gourry.net>: 1 commits
13. Arnd Bergmann <arnd@arndb.de>: 1 commits
14. Karthikeyan KS <karthiproffesional@gmail.com>: 1 commits
15. Adrian Huang (Lenovo) <adrianhuang0701@gmail.com>: 1 commits
16. Xuewen Wang <wangxuewen@kylinos.cn>: 1 commits
17. Kunwu Chan <kunwu.chan@gmail.com>: 1 commits
18. Eva Kurchatova <eva.kurchatova@virtuozzo.com>: 1 commits
19. zhaozhengzhuo <zhaozhengzhuo@uniontech.com>: 1 commits
20. Hari Mishal <harimishal1@gmail.com>: 1 commits
21. Li Youhong <liyouhong@kylinos.cn>: 1 commits
22. Nathan Gao <zcgao@amazon.com>: 1 commits
23. Kees Cook <kees+treewide@kernel.org>: 1 commits
# 23 authors, 159 commits in total
$ # stat for number of lines
$ ./lazybox/version_control/authors.py ./worktree.linux/ \
--since v7.3-rc1 --until v7.4-rc1 --skip_merge_commits \
--linux_subsystems DAMON --sortby lines
1. SJ Park <sj@kernel.org>: 2056 lines
2. Donggeun Yoo <donggeunyoo.kernel@gmail.com>: 367 lines
3. Karl Mehltretter <kmehltretter@gmail.com>: 186 lines
4. Krishna Iyer <kiyer@crusoe.ai>: 171 lines
5. Liew Rui Yan <aethernet65535@gmail.com>: 98 lines
6. Jason Angelov <jasonangelov@ucla.edu>: 64 lines
7. Zenghui Yu (Huawei) <zenghui.yu@linux.dev>: 50 lines
8. zhaozhengzhuo <zhaozhengzhuo@uniontech.com>: 38 lines
9. Enze Li <lienze@kylinos.cn>: 34 lines
10. Li Youhong <liyouhong@kylinos.cn>: 30 lines
11. Asier Gutierrez <gutierrez.asier@huawei-partners.com>: 27 lines
12. Jaeyeon Lee <jaeyeon.lee.dev@gmail.com>: 26 lines
13. Eva Kurchatova <eva.kurchatova@virtuozzo.com>: 21 lines
14. Cheng-Han Wu <hank20010209@gmail.com>: 21 lines
15. Kunwu Chan <kunwu.chan@gmail.com>: 19 lines
16. Gregory Price <gourry@gourry.net>: 16 lines
17. Arnd Bergmann <arnd@arndb.de>: 9 lines
18. Adrian Huang (Lenovo) <adrianhuang0701@gmail.com>: 8 lines
19. Nathan Gao <zcgao@amazon.com>: 7 lines
20. Hari Mishal <harimishal1@gmail.com>: 4 lines
21. Karthikeyan KS <karthiproffesional@gmail.com>: 3 lines
22. Xuewen Wang <wangxuewen@kylinos.cn>: 3 lines
23. Kees Cook <kees+treewide@kernel.org>: 2 lines
# 23 authors, 3260 lines in total
Snapshots of the number of authors, commits and changed lines for the last ten cycles are below. The snapshots for the entire DAMON history is also available [6] at the DAMON project blog.
<version> <nr_authors> <nr_commits> <nr_lines>
v7.3-rc1 23 159 3260
v7.3-rc1 21 162 2283
v7.2-rc1 14 109 3311
v7.1-rc1 9 77 1070
v7.0-rc1 12 75 1279
v6.19-rc1 10 85 1640
v6.18-rc1 13 59 864
v6.17-rc1 8 104 3785
v6.16-rc1 5 22 564
v6.15-rc1 7 68 1479
In terms of number of contributors, this was the busiest cycle in DAMON’s development history. The speed of the growth of the number has obviously reduced, though.
DAMON user-space tool (damo) also got an amount of changes.
../lazybox/version_control/authors.py ../damo \
--since 2026-08-30T13:34:40-07:00 --until 2026-11-01T13:26:31-08:00 \
--skip_merge_commits
1. SJ Park <sj@kernel.org>: 105 commits
# 1 authors, 105 commits in total
The last line for the last cycle [1] was “5 authors, 261 commits in total”. So interestingly the amount of changes for the DAMON user-space tool was reduced compared to the last cycle.
Mailing List Traffic
The DAMON mailing list was quite busy.
hkml list damon --since v7.3-rc1 --until v7.4-rc1 --collapse \
--stat_only --stdout --ignore_cache
# stat for total mails
# 2132 mails, 255 threads, 245 new threads
# 749 patches, 180 series
[...]
The traffic for the last ten cycles were like below. The numbers for the entire DAMON development history is also available [6] at DAMON project blog.
<version> <nr_mails> <nr_threads> <nr_new_threads> <nr_patches> <nr_series>
v7.4-rc1 2132 255 245 749 180
v7.3-rc1 2019 183 180 871 148
v7.2-rc1 1486 164 142 671 126
v7.1-rc1 1098 152 147 450 129
v7.0-rc1 426 111 58 223 43
v6.19-rc1 414 48 43 222 38
v6.18-rc1 563 82 62 211 53
v6.17-rc1 499 78 72 256 64
v6.16-rc1 147 40 31 63 22
v6.15-rc1 263 56 41 176 34
v6.14-rc1 260 55 34 154 23
So the traffic is continuously increasing, in terms of the number of mails and threads. But the speed of the growth of the number is getting slower than the last few cycles, in terms of the total number of mails. Nonetheless, this was yet another busiest cycle in DAMON’s history.
Events
Krishna Iyer from Crusoe continued work [7] for hugetlb pages monitoring support. As a result, the support landed on the mainline for 7.4.
Nathan Gao from AWS found and fixed [8] a nasty memory corruption bug in DAMON, as a part of their Amazon Linux 2027 preview work.
Beyond page table access-bit DAMON extension milestone 2 is [9] officially started.
Ravi shared [10] new versions of RFC patches for AMB IBS/Intel PEBS based damon
Enze Li posted [11] a patch series for adding DAMON’s rust support. Because of the lack of my Rust understanding and Rust sysfs support, we postponed the patch series. But the day for DAMON’s Rust support is apparently not very far.
DeepSeek revealed [12] their DAMON usage. They are saving 21.2% memory for agent systems using DAMON as one of the components.
First DAMON (nano) Conference [13] is held at LPC in Prague.
RFC v0 [14] for beyond-page table a-bit milestone 2 design is posted. The design is rapidly being evolved with more changes [15], though.
Newsletter Subscription
This newsletter series is posted to DAMON mailing list [16] and archived on the project blog [17], for each release. If you want a reliable delivery of this newsletter series to your inbox, subscribing to the mailing list [18] could be an option. If the mailing list traffic is too much, feel free to ask me (send mail to sj@kernel.org) to [b]cc you for each newsletter posting.
References
[1] 7.3-rc1 news: https://lore.kernel.org/20260830235014.64406-1-sj@kernel.org/ [2] First MM PR for 7.4-rc1: https://lore.kernel.org/all/20261019220030.056b79bf972b9d6a9c1aa931@linux-foundation.org/ [3] Second MM PR for 7.4-rc1: https://lore.kernel.org/20261026152120.c6ed2222b64943914563232f@linux-foundation.org/ [4] authors.py: https://github.com/sjp38/lazybox/blob/master/version_control/authors.py [5] hkml: https://github.com/hackermail [6] DAMON development stat history: https://damonitor.github.io/posts/dev_stat/ [7] DAMON hugetlb monitoring support: https://lore.kernel.org/20260908135156.97481-1-sj@kernel.org [8] DAMON memory corruption fix: https://lore.kernel.org/20260904002829.116381-1-sj@kernel.org [9] Beyong page table a-bit DAMON extension milestone 2 start: https://lore.kernel.org/20260905171537.84217-1-sj@kernel.org [10] hardware-sample based DAMON prototype: https://lore.kernel.org/20261005-damon-perf-rfc-v3-send-2026-10-03-v4-0-b03452e137f3@gmail.com [11] DAMON Rust support: https://lore.kernel.org/20260927072812.2393456-1-lienze@kylinos.cn [12] DeepSeek’s DAMON use case: https://lore.kernel.org/20260925054408.10431-1-lance.yang@linux.dev [13] DAMON (nano) Conference: https://lpc.events/event/20/contributions/2453/ [14] Beyond page table a-bit milestone 2 design: https://lore.kernel.org/20261017195747.89961-1-sj@kernel.org [15] Beyond page table a-bit milestone 2 design update: https://lore.kernel.org/20261101183404.85322-1-sj@kernel.org/ [16] DAMON mailing list: https://lore.kernel.org/damon [17] News letter on project blog: https://damonitor.github.io/tags/release_news/ [18] Mailing list subscription guide: https://subspace.kernel.org/subscribing.html