Deadlock Issue in Linux Kernel's Btrfs Filesystem by Vendor Linux

CVE-2026-74572

What is CVE-2026-74572?

A deadlock vulnerability occurs in the Linux kernel's Btrfs filesystem during metadata writeback in a zoned file system. The issue arises when the btree_writepages function retains the zoned_meta_io_lock while attempting to write metadata extent buffers. This lock contention leads to a situation where concurrent tasks, specifically a metadata writeback task and a transaction commit task, end up blocking each other. The transaction cannot proceed because it requires the same lock that the metadata writeback task currently holds, resulting in a deadlock. The solution involves modifying the check_bg_is_active function so that the lock is released before invoking the btrfs_zone_finish_one_bg function, thereby preventing the deadlock scenario. This vulnerability impacts the stability and performance of Btrfs filesystems under certain conditions.

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