Linux Kernel 6.15 Officially Released, This Is What’s New

posted by Marius Nestor on May 25, 2025,
updated May 30, 2025

Highlights of Linux 6.15 include Rust support for hrtimer and ARMv7, a new setcpuid= boot parameter for x86 CPUs, support for sched_ext to count and report internal events, x86 Intel and AMD PMU enhancements, nested virtualization support for VGICv3 on ARM, and support for emulating FEAT_PMUv3 on Apple Silicon.

Also new in Linux kernel 6.15 is a new API to receive information about mount and unmount events of filesystems, support for hardware-wrapped encryption keys in the block layer, support for 48-bit block addressing in the EROFS file system, and a new security hook for the io_uring subsystem giving security modules more control over what’s allowed.

Read on

Update (by Roy)

LWN and the original message from Torvalds:

• Linux 6.15 [LWN.net]

  So this was delayed by a couple of hours because of a last-minute bug
  report resulting in one new feature being disabled at the eleventh
  hour, but 6.15 is out there now.
  
  
  Apart from that final scramble, things looked pretty normal last week.
  Various random small fixes all over, with drivers as usual accounting
  for most of it.  But we've got some bcachefs fixes, some core
  networking, and some mm fixes in there too. Nothing looks particularly
  scary.
  
  
  And this obviously means that the merge window opens tomorrow as
  usual, and I see the usual people being proactive and having sent me
  their pull requests. It's memorial day tomorrow here in the US, but
  like the USPS, "neither snow nor rain nor heat nor gloom of night" -
  nor memorial day - stops the merge window.
  
  
  [ Actually, thinking back on the ice storm of last winter, sometimes
  snow *does* stop the merge window. But only temporarily ]
  
  
  Anyway, please keep testing,
  
  
              Linus
  

• The 6.15 kernel has been released [LWN.net]

  Significant changes in 6.15 include smarter timer-ID assignment to make checkpoint/restore operations more reliable, the ability to read status information from a pidfd after the process in question has been reaped, the PIDFD_SELF special pidfd value, nested ID-mapped mounts, zero-copy network-data reception via io_uring, The ability to read epoll events via io_uring, resilient queued spinlocks for BPF programs, guard-page enhancements allowing them to be placed in file-backed memory areas and for user space to detect their presence, the once-controversial fwctl subsystem, the optional sealing of some system mappings, and much more.

OMG Ubuntu:

• Linux 6.15 Kernel Released, This is What's New - OMG! Ubuntu

  Linus Torvalds announced the stable release of Linux 6.15 to stable on the Linux Kernel Mailing List (LKML) in his trademark laissez-faire style, noting that “nothing looks particularly scary” in the final push, so he’s happy to sign off.

  “Various random small fixes all over, with drivers as usual accounting for most of it. But we’ve got some bcachefs fixes, some core networking, and some mm fixes in there too,” he notes.

  For a whip through some of the highlights this new Linux kernel brings, read on!

Neowin:

• Linux 6.15 now available, last week brings improvements to HP ZBooks and Bcachefs

  Linus Torvalds has publicly released GNU/Linux 6.15 for public use. Here are some of the changes included for hardware and software from the past week.

CNX Software:

• Linux 6.15 Release - Main changes, Arm, RISC-V and MIPS architectures - CNX Software

  Linux 6.14 was released about two months ago with improved Wine performance with NT synchronization (NTSYNC) primitive driver, FUSE support for io_uring-based communication, amdxdna driver for AMD NPUs, uncached buffered I/Os, and many more changes. Let’s now see what the freshly-released Linux 6.15 has to offer, with a list of some notable changes, and a more in-depth look at Arm, RISC-V, and MIPS architectures often used in embedded devices.

Later coverage:

• Linux kernel 6.15 officially released

  Linus Torvalds announces the release and general availability of Linux 6.15. It is the latest stable kernel version with several new features and improvements, better hardware support, and more.

  Important new features in Linux 6.15 include Rust support for hrtimer and ARMv7 and a new setcpuid=-boot parameter for x86 processors. This is in addition to supporting sched_ext in counting and reporting internal events. Also new are improvements to Intel and AMD PMUs on x86, support for nested virtualization of VGICv3 on ARM, and emulation support for FEAT_PMUv3 on Apple Silicon.

  The same applies to an API for receiving information about the mounting and unmounting of file systems, in addition to support for hardware-encrypted keys in the block layer and 48-bit block addressing in the EROFS file system. A new security hook in the io_uring subsystem, which gives security modules more control over allowed operations, is also worth mentioning.

Bobby Borisov (Linuxiac):

• Linux Kernel 6.15 Released, Here’s What’s New

  In this new release, support for hardware-wrapped inline encryption keys in the block layer stands out, enabling transparent disk encryption without software overhead. Likewise, the new “dmem” memory accounting cgroup enhances container and cgroup memory management by tracking device memory usage.

  Under the hood, Linux kernel 6.15 refactors key locking and allocation primitives. For example, the per-VMA lock has been reimplemented as a reference count, reducing contention and simplifying code paths.

  In the memory allocator, a new defrag_mode sysctl helps to avoid fragmentation, which is especially beneficial for workloads relying on huge pages. Additionally, the buddy allocator has seen hygiene improvements and faster fallback paths, boosting allocation efficiency.

Detailed walkthrough:

• Linux 6.15, DRM scheduler, wedged events, sched_ext and more

  In 3D graphics APIs such Vulkan and OpenGL, there are some mechanisms that applications can rely to check if the GPU had reset (you can read more about this in the kernel documentation). However, there was no generic mechanism to inform userspace that a GPU reset has happened. This is useful because in some cases the reset affected not only the app involved in the reset, but the whole graphic stack and thus needs some action to recover, like doing a module rebind or even bus reset to recovery the hardware. For this release, we helped to add an userspace event for this, so a daemon or the compositor can listen to it and trigger some recovery measure after the GPU has reset. Read more in the kernel docs.

Ji M:

• Linux Kernel 6.15 Released! Mainline PPA updated for 24.04 & Higher

  Linux Kernel released new 6.15 version yesterday. Linus Torvalds announced: So this was delayed by a couple of hours because of a last-minute bug report resulting in one new feature being disabled at the eleventh hour, but 6.15 is out there now. Apart from that final scramble, things looked pretty normal last week.

Linux Magazine:

• Linux Kernel 6.15 Now Available

  The latest GNU/Linux kernel is now available with several new features/improvements and the usual bug fixes.

Collabora:

• Kernel 6.15: Divide and conquer

  The latest GNU/Linux kernel brings expanded hardware support for MediaTek and Rockchip, enhanced graphics drivers, and more. Collabora played a key role in this release, with no less than 20 authored contributors!

It's FOSS:

• Linux Kernel 6.15 Lands with Rust-based NVIDIA Driver, File System Upgrades, and More

  A new Linux release signifies progress in making the kernel faster, more reliable, and compatible with newer hardware.

  As expected, a new release has arrived two months after the earlier kernel release, marking a notable milestone in Linux's development.

The Register:

• Arrival of Linux 6.15 arrives hails end of 486-class CPUs

  As we said back at the start of this month, the change that arguably sounds like the biggest news probably isn't: this release drops support for x86 CPUs before the Intel Pentium. There are a handful of companies still making 486-class CPUs for embedded computers, but those tend not to run the latest Linux kernel, or indeed, Linux at all.

  Effectively, the kernel now only supports i586 and above. It also won't allow more than eight x86-32 CPUs in one machine, and removes 32-bit PAE support – so even on high-end x86-32 boxes, Linux 6.15 and above can't access more than 4GB of RAM.

  The few Linux distros that still offer x86-32 support often supply i686-optimized code, meaning it's aimed at the Pentium Pro (codenamed P6) or above. We suspect the kernel may follow suit before all that long. We do wonder how soon the kernel itself will drop 32-bit support completely. Ubuntu dropped x86-32 support in version 19.10 "Eoan Ermine", and Debian is set to do so next release.

Bootlin:

• Linux 6.15 released, Bootlin contributions inside

  Linux 6.15 has been released last Sunday, and we as usual encourage our readers to look at the LWN summaries of the merge window (part 1, part 2) for a good summary. CNX-Software also has a summary more oriented towards hardware support for ARM and RISC-V platforms.

TNS:

• Linux Kernel 6.15 Boosts Virtualization, GPU, and CPU Performance

  A new kernel graces the Linux community! Linux kernel 6.15 is now available, and it delivers the usual plethora of drivers, performance updates, and security mitigations. Sysadmins managing Linux servers with large quantities of RAM, lots of virtual machines, or are concerned about Spectre v2 vulnerabilities will be particularly happy with this release.

  Use the details in this article to determine whether you need to update your systems upon kernel 6.15’s release. Start by ensuring you’re familiar with the Linux release candidate system.

ZDNet:

• The Linux 6.15 kernel arrives - and it's big a victory for Rust fans

  Linus Torvalds officially announced the stable release of the Linux kernel 6.15 on May 25, 2025. Its arrival was delayed for a few hours, Torvalds said, "because of a last-minute bug report resulting in one new feature being disabled at the eleventh hour," but Linux 6.15 is here and ready for you to download and tinker with.

  The newest feature that caught my eye was that, for the first time, we have a Rust-based driver in the mainline kernel. Linux Rust fans have been waiting for this development for a long time.

  Oh, and by the way, this is not just "another driver". The Direct Rendering Manager (DRM) driver, named NOVA, empowers Nvidia's next-generation open-source graphics hardware. The driver targets Nvidia's RTX 2000 "Turing" series and newer GPUs. NOVA aims to replace the existing third-party open-source Nouveau Nvidia drivers.