Memory Management Hotfixes and Driver Updates
Linus Torvalds merged several critical hotfix branches addressing memory management issues, DMA mapping improvements, PWM driver fixes, and device tree corrections. Key fixes include hugetlb PMD sharing performance regression and memory profiling restoration for non-NUMA configurations.
Duration: PT2M
Transcript
Good morning, this is Linux Kernel Daily for Tuesday, January 21st, 2026.
Today we're covering 13 commits with no merged pull requests, but several important hotfix merges from Linus Torvalds.
The most significant merge brings memory management hotfixes from Andrew Morton's tree. David Hildenbrand from Red Hat delivered a critical fix for excessive IPI broadcasts when unsharing hugetlb PMD tables. This addresses a severe performance regression affecting fork and munmap operations that was introduced in earlier huge page fixes. The solution optimizes the process by batching IPI broadcasts and skipping unnecessary broadcasts when multiple sharers exist.
Additional memory fixes include Yosry Ahmed restoring per-memcg proactive reclaim for non-NUMA configurations, and Lorenzo Stoakes correcting page table copying logic for userfaultfd write protection. Breno Leitao resolved a potential deadlock in KFENCE's reboot notifier.
The DMA mapping fixes from Marek Szyprowski include Robin Murphy's improvements to SWIOTLB pool management, avoiding redundant pool allocations and enhancing pool lookup efficiency.
PWM subsystem updates from Uwe Kleine-König address ioctl error handling and add missing structure member initialization in the max7360 driver. The maintainer file now includes Michal Wilczynski as reviewer for Rust PWM drivers.
Rob Herring's device tree fixes tackle a reference count leak in alias scanning and improve firmware node population by supporting child node traversal.
What's next: These hotfixes target critical stability and performance issues, particularly around memory management during process lifecycle operations. The hugetlb optimization should significantly improve workloads involving frequent fork-exit cycles.
That's your Linux kernel update for today. Stay tuned for tomorrow's briefing.