{"id":"CVE-2026-98538","summary":"writeback: bound cleanup_offline_cgwb() rescans by rotating scanned inodes","details":"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-\u003eb_attached and then wb-\u003eb_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-\u003elist_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.","modified":"2026-10-19T02:46:31.451814276Z","published":"2026-10-18T15:18:05.901Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98538.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2d1da58c79b66646721a644c6eb4dd1f9c5c9327"},{"type":"WEB","url":"https://git.kernel.org/stable/c/624dd0931162523d70f9db8c120b5ec6429a9b97"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9dac137bf77e0683778fb34c86e730c6129e8cb6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c96b4d1628868e1195da1a896f79e06f350a3187"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dd4b92067238771b604b59fdda8efed6d70ee823"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f6988c90671e83db79df1b7b9d6fdb0e5947fd84"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98538.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98538"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c22d70a162d3cc177282c4487be4d54876ca55c8"},{"fixed":"2d1da58c79b66646721a644c6eb4dd1f9c5c9327"},{"fixed":"c96b4d1628868e1195da1a896f79e06f350a3187"},{"fixed":"624dd0931162523d70f9db8c120b5ec6429a9b97"},{"fixed":"dd4b92067238771b604b59fdda8efed6d70ee823"},{"fixed":"9dac137bf77e0683778fb34c86e730c6129e8cb6"},{"fixed":"f6988c90671e83db79df1b7b9d6fdb0e5947fd84"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98538.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.14.0"},{"fixed":"6.1.189"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.55"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98538.json"}}],"schema_version":"1.9.0"}