{"id":"CVE-2026-89759","state":"PUBLISHED","title":"mm/kmemleak: avoid soft lockup when scanning task stacks","description":"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.","publishedAt":"2026-09-11T19:47:01.313Z","updatedAt":"2026-10-30T12:32:57.075Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"2567818c2776d0a820506c3612261d9e24af7164","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"f1cd6c4c35243377882c47236281d03ee3be6eeb","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"9a1b12c06c192290b8479de48f66f1e75d89c4b7","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"3fc8044251de21555fb02c365fa681bab8b0db55","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"1838c704bcb4fd3556cf67513c6f97a39099e35c","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"5d10d4e19e6daa487f0cd0ea6cba472325de92f9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/kmemleak.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/kmemleak.c"]}],"references":["https://git.kernel.org/stable/c/2567818c2776d0a820506c3612261d9e24af7164","https://git.kernel.org/stable/c/f1cd6c4c35243377882c47236281d03ee3be6eeb","https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7","https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55","https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c","https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89759.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89759","state":"PUBLISHED","datePublished":"2026-09-11T19:47:01.313Z","dateUpdated":"2026-10-30T12:32:57.075Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.763Z"},"containers":{"cna":{"title":"mm/kmemleak: avoid soft lockup when scanning task stacks","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"2567818c2776d0a820506c3612261d9e24af7164","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"f1cd6c4c35243377882c47236281d03ee3be6eeb","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"9a1b12c06c192290b8479de48f66f1e75d89c4b7","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"3fc8044251de21555fb02c365fa681bab8b0db55","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"1838c704bcb4fd3556cf67513c6f97a39099e35c","versionType":"git"},{"version":"c4b28963fd79457315783b3b0f21c01eb88cfdc1","status":"affected","lessThan":"5d10d4e19e6daa487f0cd0ea6cba472325de92f9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/kmemleak.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.10","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/kmemleak.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/2567818c2776d0a820506c3612261d9e24af7164"},{"url":"https://git.kernel.org/stable/c/f1cd6c4c35243377882c47236281d03ee3be6eeb"},{"url":"https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7"},{"url":"https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55"},{"url":"https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c"},{"url":"https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:32:57.075Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}