CVE-2026-98538

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

writeback: bound cleanup_offline_cgwb() rescans by rotating scanned inodes

cleanup_offline_cgwb() prepares at most WB_MAX_INODES_PER_ISW inodes

per call and is called again until the dying wb is drained, but every

call walks wb->b_attached and then wb->b_dirty_time from the same end.

Inodes already prepared (they stay on the list with I_WB_SWITCH set

until the switch worker runs) and inodes that cannot be switched

(I_FREEING, I_WILL_FREE, !SB_ACTIVE, DAX, already on the target wb)

stay where they are, so each pass rescans a growing run of them under

wb->list_lock and a full drain is quadratic in the number of inodes on

the list. With ~17M inodes attached to one dying cgwb we saw this end

in soft lockups, with CPUs reported stuck for 21-48s.

Walk both lists from the oldest end and move every scanned inode to

the newest end, so the next pass starts where the previous one stopped

and the drain becomes linear. b_attache

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References