Bypass Kernel Barriers: Fuzzing Linux Kernel in Userspace With LKL

Xuan Xing & Eugene Rodionov gave a talk about fuzzing the Linux kernel interfaces fully in user space using LKL (Linux Kernel Library).

Video: https://www.youtube.com/watch?v=Wxmi-2ROYNk
Slides: https://static.sched.com/hosted_files/lssna2025/01/Bypass%20Kernel%20Barriers_%20Fuzzing%20Linux%20Kernel%20in%20Userspace%20with%20LKL.pdf

Bijan's DAMON patch series[1] for dynamic NUMA memory weighted interleaving that shows ~25% performance improvements on a test is now merged into mm-new, and looks good to me. I'm more than exciting to see this is on the track and grateful to have a chance to participate!

[1] https://lore.kernel.org/20250709005952.17776-1-bijan311@gmail.com

#linux #kernel #damon #interleaving

And OSSummit NA 2025 DAMON talk video is now available: https://youtu.be/Ou4BQQ0Ved8?si=ZrhjCGI4gRyJmODn

#linux #kernel #damon #ossummit #ossummitna #ossummitna25

RE: https://social.kernel.org/objects/f03afaa9-5786-49eb-8c1d-2b6b6261685e

Access pattern heatmap is powerful visualization, but exploring the time/space is not that easy[1]. To help that, we added an interactive zoom and scroll mode of the heatmap. You can try that with `damo report heatmap --interacrive_edit`. Attaching a demo gif.

[1] https://damonitor.github.io/posts/why_the_heatmap_is_not_showing_the_expected_access_patterns/

#linux #kernel #dmon #damo

OSSummit NA was great. I met old and new great people. DAMON talk was also done very well, thanks to great audiences. The video would be available soon. Meanwhile, you could get the slides for the talk at the conference web site[1] and GitHub[2].

[1] https://sched.co/1zfmE
[2] https://github.com/damonitor/talks/tree/master/2025/ossna

#linux #kernel #damon #ossna

Bcachefs may be headed out of the kernel

https://lwn.net/Articles/1027289/ #LWN

This graph is the one I'm most excited about: the lifetime of security flaws in Linux is finally starting to get shorter (and the number of fixed flaws continues to rise).

https://hachyderm.io/@LinuxSecSummit@social.kernel.org/114750428620118674

LSFMM+BPF 2025 reporting complete

https://lwn.net/Articles/1026338/ #LWN

It took a long time and over 60 articles but, at @lwn, we have finally managed to complete our reporting from the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit. If you want to know what is going on in those core parts of the kernel, this is the place to look.

We've put together an EPUB version of the whole set as well — good bedtime reading!

https://lwn.net/Articles/1026338/

An interesting ISCA'25 paper for better memory tiering is published. The paper uses DAMON and masim for showing access patterns of artificial and realistic workloads.

https://dl.acm.org/doi/10.1145/3695053.3731001

#linux #kernel #damon #masim #memory_tiering

I'll travel Denver next week for DAMON talk at Open Source Summit North America. If you have any topic for in-person DAMON beer/coffee/tea chat, please reach out to me! https://lore.kernel.org/20250620204743.98321-1-sj@kernel.org

#linux #kernel #damon #ossna

RE: https://social.kernel.org/objects/c5a2bd49-eb02-4dbe-a1f1-00dd85f4b512

A new DAMON user-space tool feature of today is drawing heatmap after sorting regions on the space by their access temperature.

The feature can be used with 'damo report heatmap --sort_temperature'. The access temperature calculation can be customized using '--temperature_weights'.

Attaching heatmps of a DAMON-snapshot and a DAMON-record, for unsorted and sorted heatmaps.

#linux #kernel #damon #damo

Intel has published another excellent ArXiv paper[1] for memory tiering. The research used DAMON for a validation of the behavior of their approach (GPAC).

[1] https://arxiv.org/pdf/2506.06067

#linux #kernel #damon

I use 'masim' for testing DAMON against artificial access patterns. I recently started thinking it might be useful for not only DAMON but also other memory management systems that I have interest, such as memory tiering and compressions. So I finally got a time to document its configuration format[1], about 7 years after its first release.

[1] https://github.com/sjp38/masim/blob/master/README.md

#linux #kernel #damon #masim

Linus Torvalds Rejects The Idea Of Enabling DAMON By Default In The Linux Kernel

DAMON is a nifty data access monitoring solution for the Linux kernel developed by Amazon and other parties for system monitoring and performance/efficiency optimizations and more. But it's not so ground-breaking that it's worth enabling by default in all Linux kernel builds, Linus Torvalds has decided...
https://www.phoronix.com/news/Linux-DAMON-By-Default-No

Ticket sales for Kernel Recipes 2025 are now open! The conference will take place from September 22 to 24, 2025, in Paris. The agenda is still in the works, but you can already check out the list of speakers and a few of the topics online.

https://kernel-recipes.org/en/2025/

If you're a student, we’re offering a 50% discount—just get in touch with us!

See you in september!

Like everybody else, LWN is affected by the current turbulence in the political and economic spheres; we expect to get through this period, but there will be some challenges.

To put it bluntly: starting around the beginning of March, we have observed a distinct drop in both new subscriptions and renewals. [...] #OpenSource #Linux #LWN

https://lwn.net/Articles/1019217/

DAMON user-space tool's heatmap visualization has recently advanced. I wrote more details on the blog: https://damonitor.github.io/posts/damo_heatmap_modernization_2025_06/

#linux #kernel #damon #damo

Changes for enabling CONFIG_DAMON by default[1] have just merged[2] into the mainline, by the second MM subsystem pull request for Linux 6.16-rc1. This will help DAMON be better tested and easier to be used.

[1] https://lore.kernel.org/all/20250521042755.39653-1-sj@kernel.org/
[2] https://lore.kernel.org/all/174891081008.961800.5493448222601669134.pr-tracker-bot@kernel.org/

#linux #kernel #damon

Andrew Morton posted an MM pull request[1] for Linux 6.16-rc1, and it is now merged into the mainline. It includes many interesting changes including DAMON patches[2] for more self-driven memory tiering.

[1] https://lore.kernel.org/all/20250531145342.383090aa5ed5bcefee0740d5@linux-foundation.org/
[2] https://lore.kernel.org/all/20250420194030.75838-1-sj@kernel.org/

#linux #kernel #damon #mm #pullrequest