{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98536","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.355Z","datePublished":"2026-10-18T15:18:04.013Z","dateUpdated":"2026-10-19T09:21:19.730Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-19T09:21:19.730Z"},"descriptions":[{"lang":"en","value":"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 -> bpf_trampoline_update ->\nunregister_ftrace_direct -> ftrace_shutdown -> 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."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/backing-dev.c"],"versions":[{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"863049b4018237d1590cd13b16e9fe9c0faad2c6","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"42462b5bb0dec57db7f85d0f77655c737d45754d","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"ebf1555ad2821be06f87a88ffd9a2cab8d2200e1","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"4eb889649eaf65f4a5727b04ba1c017b7d05bb16","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"fd3bf32279df98751364b3609eb100a3e42f253b","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"260f586a80e7f624dd7f069898a75a904f34d373","status":"affected","versionType":"git"},{"version":"c22d70a162d3cc177282c4487be4d54876ca55c8","lessThan":"407a5d205179a4ab186571b0e16ec42725dc77bc","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/backing-dev.c"],"versions":[{"version":"5.14","status":"affected"},{"version":"0","lessThan":"5.14","status":"unaffected","versionType":"semver"},{"version":"5.15.222","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.112","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.55","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.9","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.3"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/863049b4018237d1590cd13b16e9fe9c0faad2c6"},{"url":"https://git.kernel.org/stable/c/42462b5bb0dec57db7f85d0f77655c737d45754d"},{"url":"https://git.kernel.org/stable/c/ebf1555ad2821be06f87a88ffd9a2cab8d2200e1"},{"url":"https://git.kernel.org/stable/c/4eb889649eaf65f4a5727b04ba1c017b7d05bb16"},{"url":"https://git.kernel.org/stable/c/fd3bf32279df98751364b3609eb100a3e42f253b"},{"url":"https://git.kernel.org/stable/c/260f586a80e7f624dd7f069898a75a904f34d373"},{"url":"https://git.kernel.org/stable/c/407a5d205179a4ab186571b0e16ec42725dc77bc"}],"title":"writeback: report a Tasks-RCU quiescent state per cgwb drain pass","x_generator":{"engine":"bippy-1.2.0"}}}}