{"id":"CVE-2026-90183","summary":"blk-iolatency: clear delay state when freeing policy data","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-iolatency: clear delay state when freeing policy data\n\nio.latency can throttle a group which has no latency target of its own.\nWhen a sibling misses its target, check_scale_change() scales down its\npeers, and a peer that reaches queue depth one gets blkcg_use_delay()\ncalled on it on every further scale-down, even with min_lat_nsec == 0.\n\niolatency_pd_offline() resets the target through\niolatency_set_min_lat_nsec(), which clears the delay only on a nonzero\nto zero transition, so it never clears such a peer.  Freeing the policy\ndata then leaves blkg-\u003euse_delay set and blkcg-\u003econgestion_count\nelevated with nothing left that can drop it.\n\nblk_cgroup_congested() then returns true for every task in that cgroup\nand its descendants for as long as the cgroup lives: page_cache_sync_ra()\ncuts readahead to a single page, page_cache_async_ra() skips it\naltogether, and __folio_throttle_swaprate() takes swap_avail_lock and\nschedules a throttle on anonymous folio allocation.\n\nClear the delay in iolatency_pd_free().  By then bio-held blkg\nreferences have drained, or the queue is frozen for policy\ndeactivation, so check_scale_change() cannot re-arm it.  The free\ncallback can also see policy data which was never attached to a blkg,\nhence the pd-\u003eblkg check.","modified":"2026-09-19T03:47:24.908134829Z","published":"2026-09-17T16:07:07.045Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90183.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/02f1b90ab33ef99c89dd96a385b432ff57abc64d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8935bf22c0a0db517a7f72f7097300e05dd852f5"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90183.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90183"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d70675121546c35feaceebf7ed9caed8716640f3"},{"fixed":"02f1b90ab33ef99c89dd96a385b432ff57abc64d"},{"fixed":"8935bf22c0a0db517a7f72f7097300e05dd852f5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90183.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90183.json"}}],"schema_version":"1.9.0"}