Kernel: SB_RDONLY races, KVM teardown, and offload cleartext fixes

Kernel traffic on 2026-11-04 focused on filesystem error-path races, KVM teardown hardening, and several networking security fixes. Multiple large patch series also advanced THP swap handling and a Rust SPDM requester.

Filesystem SB_RDONLY handling after errors

Christian Brauner posted a v2 34-patch series that stops filesystems from setting SB_RDONLY on errors without holding s_umount. The work resolves freeze races and remount problems in ext4, xfs, gfs2, ntfs, exfat and others. Maintainers and operators of those filesystems gain consistent error paths that avoid stuck or inconsistent mount states.

KVM uaccess fixes for dying VMs

The KVM maintainer posted a v4 23-patch series that fixes uaccess corruption of unrelated processes during VM teardown in nested VMX, together with related hardening. Bad accesses from a dying virtual machine can no longer affect other processes. Hosts running nested virtualization benefit from the closed teardown race.

PMD-level swap entries for anonymous THPs

A v8 30-patch memory-management series adds PMD-level swap entries so swapped anonymous transparent huge pages keep huge mappings across swap-out and swap-in instead of splitting to PTEs. Large anonymous mappings under reclaim therefore retain THP benefits. Workloads that rely on THP performance under memory pressure are the primary audience.

PSP and kTLS cleartext offload leaks

A v4 seven-patch netdev series fixes bugs that could transmit PSP and kTLS offloaded packets unencrypted for IPv6 headers, fragments, and ICMP errors. Offloaded encrypted contents are no longer sent in cleartext under those conditions. Operators using hardware TLS or PSP offload should treat the series as a confidentiality fix.

Rust SPDM requester

A v4 22-patch series adds a Rust SPDM requester to the kernel for safer parsing of complex untrusted authentication data. Rust is used to harden handling of malformed inputs in the security protocol. The work extends Rust adoption into device-authentication paths that process untrusted data.

Maple tree and rhashtable library fixes

A four-patch series corrects a maple_tree RCU NULL dereference and an rhashtable vmalloc deadlock. Linus Torvalds called a related kvmalloc GFP_ATOMIC change buggy during the discussion. The fixes close crash and hang paths in widely used core data structures.

Genetlink multicast group join race

A v4 two-patch series closes a genetlink race that let unprivileged sockets join privileged multicast groups through unowned IDs or unregister timing. The change restores proper access control on generic netlink multicast. Systems exposing genetlink interfaces lose an unprivileged join path.

Overlayfs pull and VFS helper rewrite

Linus Torvalds pulled an overlayfs fixes series for 7.3 but rewrote the new try_take_dentry_name_snapshot VFS helper after criticizing its approach. Overlayfs changes land while the helper takes a different form. Overlayfs users and VFS developers should note the revised helper semantics.