{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "c22d70a162d3cc177282c4487be4d54876ca55c8"
            },
            {
              "fixed": "863049b4018237d1590cd13b16e9fe9c0faad2c6"
            },
            {
              "fixed": "42462b5bb0dec57db7f85d0f77655c737d45754d"
            },
            {
              "fixed": "ebf1555ad2821be06f87a88ffd9a2cab8d2200e1"
            },
            {
              "fixed": "4eb889649eaf65f4a5727b04ba1c017b7d05bb16"
            },
            {
              "fixed": "fd3bf32279df98751364b3609eb100a3e42f253b"
            },
            {
              "fixed": "260f586a80e7f624dd7f069898a75a904f34d373"
            },
            {
              "fixed": "407a5d205179a4ab186571b0e16ec42725dc77bc"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.14.0"
            },
            {
              "fixed": "5.15.222"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "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"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98536.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: report a Tasks-RCU quiescent state per cgwb drain pass\n\ncleanup_offline_cgwbs_workfn() drains a dying cgwb by calling\ncleanup_offline_cgwb() until it returns false, with a cond_resched()\nbetween passes.  On a CONFIG_PREEMPTION kernel that cond_resched() does\nnothing: _cond_resched() is a plain \"return 0\", and under PREEMPT_DYNAMIC\nthe full and lazy modes disable it.  Since commit 7dadeaa6e851 (\"sched:\nFurther restrict the preemption modes\") those are the only two models on\nthe architectures with PREEMPT_LAZY support, arm64 and x86 among them, so\nthe drain loop never reports a Tasks-RCU quiescent state.\n\nA worker draining a cgwb with millions of attached inodes runs for\nminutes.  On a 6.18 arm64 host in lazy mode the cgwb worker drained one\ndying cgroup's writeback domain for over 11 minutes.  A BPF program unlink\n(bpf_trampoline_unlink_prog -\u003e bpf_trampoline_update -\u003e\nunregister_ftrace_direct -\u003e ftrace_shutdown -\u003e synchronize_rcu_tasks())\nwaited on that grace period while holding the trampoline mutex, 42 tasks\nqueued behind it in D state, and the hung task detector fired at 614 s and\npanicked the host.  Any BPF or ftrace detach during a long drain inherits\nthe drain's length.\n\nFix this by calling cond_resched_tasks_rcu_qs() so we do not stall out\nanybody who calls sycnrhonize_rcu_tasks().  We put this in a do { } while\nloop because if we have many small cgroups cleanup_offline_cgwb() will\nreturn false and we will never call cond_resched_tasks_rcu_qs(), creating\nthe same problem.",
  "id": "CVE-2026-98536",
  "modified": "2026-10-20T02:30:46.490887432Z",
  "published": "2026-10-18T15:18:04.013Z",
  "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/260f586a80e7f624dd7f069898a75a904f34d373"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/407a5d205179a4ab186571b0e16ec42725dc77bc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/42462b5bb0dec57db7f85d0f77655c737d45754d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4eb889649eaf65f4a5727b04ba1c017b7d05bb16"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/863049b4018237d1590cd13b16e9fe9c0faad2c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ebf1555ad2821be06f87a88ffd9a2cab8d2200e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fd3bf32279df98751364b3609eb100a3e42f253b"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98536.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98536"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "writeback: report a Tasks-RCU quiescent state per cgwb drain pass"
}