Executive Summary

I just read the Linux Kernel 7.3 release notes, and the main focus is clear: performance. What's most interesting to me is the new mechanism for handling GPUs that run out of VRAM while gaming, along with two lock fixes in the memory subsystem whose impact is immediately felt in system responsiveness.

Problems Solved

Previously, when VRAM ran out while playing a demanding game, it would usually freeze or performance would collapse because the system had no elegant way to offload non-critical data to RAM. Natalie Vock from Valve has been working on this incrementally, and the first piece has landed in 7.3: the kernel can now move less important data from VRAM to system RAM once graphics memory is full. A concrete example mentioned in the article - Indiana Jones and the Great Circle requests 9GB on an 8GB card and still runs well.

There are also two lock contention issues that have been fixed. A ZTE engineer found a lookup in KSM (the feature that merges identical memory pages) that could hold a lock for hundreds of milliseconds and freeze applications when memory was under pressure. A similar issue existed in zsmalloc, which is used by zRAM and Zswap to store compressed memory, and was fixed by Wenchao Hao from Xiaomi.

Key Features and Code Examples

A few things I think are worth noting:

  • VRAM overflow handling (Valve) - still in an early stage upstream; the full version already exists in SteamOS but hasn't fully landed in this kernel yet.
  • KSM lock fix - worst case dropped from 705ms to under 2ms in stress tests.
  • zsmalloc lock fix - speedup of up to 1.83x on Raspberry Pi 4B and 1.4x on a 20-core Intel system.
  • amd-pstate Dynamic EPP per-core - previously could only be enabled system-wide, now it can be set per-core via the powersave governor (opt-in).
  • Radeon GPU hang recovery - Timur Kristóf (Valve) made the reset only touch the GFX block, so VRAM doesn't get reset along with it.
  • AMD HSMP protocol v7 + new ioctl in the PMF driver - groundwork for Zen 6 Family 1Ah Model 80H, which is planned to release in January 2027.
  • A new amd_halo_led driver for controlling LEDs on Ryzen AI Halo mini PCs (previously only possible via AMD's own Debian-based distro, the Ryzen AI Developer Platform).

I can imagine this per-core Dynamic EPP feature being useful for people who like tuning CPU power behavior. Here's roughly what using it looks like (illustrated from the article's description, not from direct testing):

# Ilustrasi: mengaktifkan preferensi EPP "dynamic" per-core
# di bawah governor powersave (fitur baru amd-pstate, Linux 7.3)
echo powersave | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo dynamic | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference

Beyond that, there are a few brief but notable hardware updates: RISC-V adds 11 new ISA extensions and now uses UEFI runtime services for restart/poweroff, Apple M3 Pro/Max/Ultra gets initial boot support, the space-grade Intel Starfire chip (based on Panther Lake) starts getting its first kernel changes, the logitech-hidpp driver can remap mouse/keyboard buttons for enthusiasts via HID++ 2.0, hid-steam now supports the Steam Controller 2026, and ThinkPads with USB-C Restricted Mode Security finally get support in Linux.

Impact and Upgrade Notes

Linux 7.3 was released about two months after 7.2, and the merge window for 7.4 opened as soon as the 7.3 final came out. Linus Torvalds himself said the last week was quiet enough that 7.3 released as planned, even though he was on a family vacation and took time to go diving before continuing merging in the afternoon.

For those who want to try it quickly, the easiest route is apparently via Ubuntu 26.10 (this year's interim release), or waiting for the update to land in Fedora Workstation and Arch Linux and its derivatives. Another option is installing the mainline kernel directly on Ubuntu, but the risk is higher - it's recommended to back up first because of the possibility of data loss.

What I'm actually most looking forward to isn't in this release, but the continuation of Valve's work on VRAM overflow. If the full patch set eventually lands completely upstream (currently still exclusive to SteamOS), it could be a game changer for Linux gaming setups with small VRAM GPUs.

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First announced on It's FOSS News. Read the original source for full details.