{"id":"CVE-2026-89759","summary":"mm/kmemleak: avoid soft lockup when scanning task stacks","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/kmemleak: avoid soft lockup when scanning task stacks\n\nPatch series \"mm/kmemleak: avoid soft lockup when scanning task\", v3.\n\nkmemleak_scan() scans every task stack under one rcu_read_lock() with no\nreschedule point, which can trip the soft lockup watchdog on hosts with\nvery many threads.\n\nThat prints the following message, depending on the workload+host\nconfiguration:\n\n      watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\n       scan_block\n       kmemleak_scan\n       kmemleak_scan_thread\n       kthread\n\nPatch 1 walks the tasks with find_ge_pid() so the scan reschedules between\ntasks\n\nPatches 2-3 let the scan loops stop early once a scan is interrupted.\n\n\nThis patch (of 3):\n\nkmemleak_scan() walks every thread and scans its kernel stack under a\nsingle rcu_read_lock() with no reschedule point.  On a host with very many\nthreads -- amplified by KASAN/lockdep in debug builds -- this loop can hog\na CPU long enough to trip the soft lockup watchdog:\n\n  watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\n   scan_block\n   kmemleak_scan\n   kmemleak_scan_thread\n   kthread\n\nA cond_resched() cannot be added directly: the loop runs inside an RCU\nread-side critical section.\n\nWalk the tasks one PID at a time with find_ge_pid(), taking the RCU read\nlock only to look up and pin each task.  The stack is then scanned with no\nlock held, so cond_resched() runs between tasks and the scan stops early\non scan_should_stop().  This follows the next_tgid()/task_seq_get_next()\niteration pattern and keeps each RCU critical section short.","modified":"2026-09-13T03:47:20.881406384Z","published":"2026-09-11T19:47:01.313Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89759.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89759.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89759"},{"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":"c4b28963fd79457315783b3b0f21c01eb88cfdc1"},{"fixed":"9a1b12c06c192290b8479de48f66f1e75d89c4b7"},{"fixed":"3fc8044251de21555fb02c365fa681bab8b0db55"},{"fixed":"1838c704bcb4fd3556cf67513c6f97a39099e35c"},{"fixed":"5d10d4e19e6daa487f0cd0ea6cba472325de92f9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89759.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.10.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89759.json"}}],"schema_version":"1.9.0"}