Linux Kernel 6.18 RC4 is Released: Linus Torvalds Calls it ‘Very Normal’

Linus Torvalds announced the fourth release candidate (RC4) for the upcoming Linux Kernel version 6.18. He tagged and released this version on 2 November 2025.

The Linux 6.18-rc4 release candidate was cut slightly early by Torvalds due to travel, but he noted that things look calm and normal, suggesting the release is on schedule.

In the Kernel 6.18-rc4 announcement mail, he noted that the overall statistics for 6.18-rc4 look "very normal", in terms of both the number of changes and the distribution of those changes across different areas of the kernel.

What's New Linux Kernel 6.18 RC4

Here is a summary of what 6.18-rc4 brought to the table:

1. Core Focus Areas

The bulk of the changes in 6.18-rc4 consist of driver fixes. The top three areas leading the charge for these driver fixes are:

1. GPU drivers
2. Networking drivers
3. Sound drivers

The non-driver changes are widely distributed, addressing various parts of the kernel, including core networking, filesystems, core kernel components, and architecture-specific fixes.

Linus characterized many of these fixes as trivial one- and few-liners, with nothing looking "particularly scary".

Key Fixes and Updates

1. Driver Fixes (GPU, Networking, Sound)

• GPU Drivers: There were various fixes across AMDGPU, MSM, and XE drivers. These included fixes for SPDX headers, an HDR workaround for a specific eDP display, and addressing issues like a race condition in drm_sched_entity_select_rq(). The drm/msm updates fixed issues like GEM free for imported dma-bufs, page table preallocation errors, and several DPU display issues.
• Networking and Bluetooth: Core networking fixes were included, along with specific fixes for memory leaks in sfc and nfp. Updates were made to mptcp (e.g., fixing subflow rcvbuf adjustment, dropping a bogus optimization, and window probe issues). Bluetooth saw fixes for a corruption issue in h4_recv_buf(), race conditions in hci_cmd_sync_dequeue_once, and handling of ISO connection destination types.
• Wi-Fi/Wireless: mac80211 received updates, including a fix to reset FILS discovery and unsol probe response intervals and a fix for key tailroom accounting leakage. Fixes were also applied to ath12k and brcmfmac.
• Sound Drivers: Fixes were applied to ASoC (e.g., Intel AVS stream management, fsl_sai bit order fix for DSD format) and ALSA (e.g., various HDA Realtek quirks for HP and Lenovo laptops, and fixes to USB-audio control pipe direction).

2. Filesystem Updates

The filesystems that saw specific fixes include SMB, XFS, and NFSD.

• SMB/KSMBD: Client-side fixes were included, such as addressing the lack of IPC in DFS cache refreshes and adding logic to wait for SMBDIRECT_SOCKET_DISCONNECTED during transport cleanup (client and server).
• XFS: Changes were made to prevent garbage collection (gc) from selecting the same zone twice and documenting another racy garbage collection case.
• NFSD: Fixes included defining actions for the new time_deleg FATTR4 attributes and addressing a crash in nfsd4_read_release().

3. Architecture and Core Kernel

• Architecture Fixes (x86, s390): X86 received microcode updates limiting Entrysign signature checking to known generations and extending the Zen6 model range. S390 saw fixes to restore IRQ unconditionally for zPCI devices and avoid deadlocks during error recovery. X86 FPU state is now ensured upon signal delivery.
• VFIO and Selftests: New selftests were added, primarily related to issues found in VFIO. This included sanitization fixes for overflow in vfio/type1 and updates to DMA map/unmap helpers to support more test kinds.
• sched_ext: Fixes addressed scx_kick_pseqs corruption on concurrent scheduler loads, fixed flag checks for deferred callbacks, and ensured lazy allocation of certain structures using kvzalloc().
• Kbuild: An update was made to align the modinfo section for Secureboot Authenticode EDK2 compatibility.

Test Linux 6.18-rc4

As usual, users and enthusiasts are asked to thoroughly test the latest Kernel 6.18-rc4. The Linux Kernel 6.18 RC4 version can be downloaded from the Kernel.org website or the Linus Torvalds's git tree.

Future Release Scheduling Note

Linus noted that while 6.18 is proceeding normally, the schedule for the next release (6.19) might be affected by upcoming events: the yearly kernel maintainer summit (and associated travel) during the merge window, and the whole holiday season later in the release cycle.

He suspects he will likely "drag out the 6.19 release by a week to make up for time lost to holidays", depending on how the 6.18 cycle concludes.