{"id":"CVE-2026-98538","title":"writeback: bound cleanup_offline_cgwb() rescans by rotating scanned inodes","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: bound cleanup_offline_cgwb() rescans by rotating scanned inodes\n\ncleanup_offline_cgwb() prepares at most WB_MAX_INODES_PER_ISW inodes\nper call and is called …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 2d1da58c79b66646721a644c6eb4dd1f9c5c9327","Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < c96b4d1628868e1195da1a896f79e06f350a3187","Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 624dd0931162523d70f9db8c120b5ec6429a9b97","Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < dd4b92067238771b604b59fdda8efed6d70ee823","Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 9dac137bf77e0683778fb34c86e730c6129e8cb6","Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < f6988c90671e83db79df1b7b9d6fdb0e5947fd84","Linux 5.14"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:18:05.901Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98538","references":[{"url":"https://git.kernel.org/stable/c/2d1da58c79b66646721a644c6eb4dd1f9c5c9327"},{"url":"https://git.kernel.org/stable/c/c96b4d1628868e1195da1a896f79e06f350a3187"},{"url":"https://git.kernel.org/stable/c/624dd0931162523d70f9db8c120b5ec6429a9b97"},{"url":"https://git.kernel.org/stable/c/dd4b92067238771b604b59fdda8efed6d70ee823"},{"url":"https://git.kernel.org/stable/c/9dac137bf77e0683778fb34c86e730c6129e8cb6"},{"url":"https://git.kernel.org/stable/c/f6988c90671e83db79df1b7b9d6fdb0e5947fd84"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.276Z","slug":"CVE-2026-98538","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: bound cleanup_offline_cgwb() rescans by rotating scanned inodes\n\ncleanup_offline_cgwb() prepares at most WB_MAX_INODES_PER_ISW inodes\nper call and is called again until the dying wb is drained, but every\ncall walks wb->b_attached and then wb->b_dirty_time from the same end.\nInodes already prepared (they stay on the list with I_WB_SWITCH set\nuntil the switch worker runs) and inodes that cannot be switched\n(I_FREEING, I_WILL_FREE, !SB_ACTIVE, DAX, already on the target wb)\nstay where they are, so each pass rescans a growing run of them under\nwb->list_lock and a full drain is quadratic in the number of inodes on\nthe list. With ~17M inodes attached to one dying cgwb we saw this end\nin soft lockups, with CPUs reported stuck for 21-48s.\n\nWalk both lists from the oldest end and move every scanned inode to\nthe newest end, so the next pass starts where the previous one stopped\nand the drain becomes linear. b_attached is unordered, so nobody sees\nthe reorder there. b_dirty_time is ordered by dirtied_when, but the\noldest unscanned inode stays at the end move_expired_inodes() picks\nfrom, sync takes the whole list regardless of order, and prepared\ninodes leave the list as soon as the switch work runs and get a new\ndirtied_time_when on the new wb anyway, so the only inodes left out of\norder are the ones that can never switch (DAX), and only on the dying\nwb.\n\n## Affected\n\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 2d1da58c79b66646721a644c6eb4dd1f9c5c9327`\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < c96b4d1628868e1195da1a896f79e06f350a3187`\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 624dd0931162523d70f9db8c120b5ec6429a9b97`\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < dd4b92067238771b604b59fdda8efed6d70ee823`\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < 9dac137bf77e0683778fb34c86e730c6129e8cb6`\n- `Linux >= c22d70a162d3cc177282c4487be4d54876ca55c8 < f6988c90671e83db79df1b7b9d6fdb0e5947fd84`\n- `Linux 5.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}