{"id":"CVE-2026-98538","published":"2026-10-18T16:17:05.613","lastModified":"2026-10-19T10:19:09.527","description":"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 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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/2d1da58c79b66646721a644c6eb4dd1f9c5c9327","tags":[]},{"url":"https://git.kernel.org/stable/c/624dd0931162523d70f9db8c120b5ec6429a9b97","tags":[]},{"url":"https://git.kernel.org/stable/c/9dac137bf77e0683778fb34c86e730c6129e8cb6","tags":[]},{"url":"https://git.kernel.org/stable/c/c96b4d1628868e1195da1a896f79e06f350a3187","tags":[]},{"url":"https://git.kernel.org/stable/c/dd4b92067238771b604b59fdda8efed6d70ee823","tags":[]},{"url":"https://git.kernel.org/stable/c/f6988c90671e83db79df1b7b9d6fdb0e5947fd84","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}