syzbot


INFO: task hung in kvm_mmu_uninit_tdp_mmu (2)

Status: premoderation: reported on 2026/01/24 19:57
Reported-by: syzbot+aebf766ff4e64a1b32c9@syzkaller.appspotmail.com
First crash: 16d, last: 2d05h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in kvm_mmu_uninit_tdp_mmu 1 115 90d 234d 0/1 auto-obsoleted due to no activity on 2026/01/01 13:24

Sample crash report:
INFO: task syz.2.589:2026 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.589       state:D stack:0     pid:2026  tgid:2026  ppid:291    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5996 [inline]
 __schedule+0x134f/0x1ea0 kernel/sched/core.c:7843
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 schedule_timeout+0xc7/0x3b0 kernel/time/timer.c:2596
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x369/0x650 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 rcu_barrier+0x415/0x540 kernel/rcu/tree.c:4657
 kvm_mmu_uninit_tdp_mmu+0x1df/0x210 arch/x86/kvm/mmu/tdp_mmu.c:51
 kvm_mmu_uninit_vm+0x27/0x60 arch/x86/kvm/mmu/mmu.c:6572
 kvm_arch_destroy_vm+0x398/0x420 arch/x86/kvm/x86.c:12961
 kvm_destroy_vm virt/kvm/kvm_main.c:1355 [inline]
 kvm_put_kvm+0xb04/0x12c0 virt/kvm/kvm_main.c:1392
 kvm_vm_release+0x47/0x70 virt/kvm/kvm_main.c:1415
 __fput+0x1fb/0xa00 fs/file_table.c:429
 ____fput+0x20/0x30 fs/file_table.c:457
 task_work_run+0x1e5/0x260 kernel/task_work.c:246
 resume_user_mode_work+0x35/0x50 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x63/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fc800b9aeb9
RSP: 002b:00007ffd722be718 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fc800e17da0 RCX: 00007fc800b9aeb9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fc800e17da0 R08: 00007fc800e16128 R09: 0000000000000000
R10: 00000000003ffcc4 R11: 0000000000000246 R12: 000000000001895b
R13: 00007fc800e15fac R14: 0000000000018723 R15: 00007fc800e15fa0
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 e538f3f6a543b135812147031d083fd1f2699041
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xdad/0xf00 kernel/hung_task.c:423
 kthread+0x2c9/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 33 Comm: rcuop/1 Not tainted syzkaller #0 e538f3f6a543b135812147031d083fd1f2699041
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:unwind_next_frame+0x2fa/0x750 arch/x86/kernel/unwind_frame.c:305
Code: 00 00 00 48 83 c3 48 48 89 d8 48 c1 e8 03 80 3c 10 00 74 08 48 89 df e8 94 a3 9a 00 48 c7 03 00 00 00 00 b0 01 e9 a2 02 00 00 <4c> 8d 6b 50 4d 89 ee 49 c1 ee 03 41 80 3c 16 00 74 12 4c 89 ef e8
RSP: 0018:ffffc90000230188 EFLAGS: 00000202
RAX: ffffc90000227f30 RBX: ffffc90000230208 RCX: 0000000000230200
RDX: dffffc0000000000 RSI: ffffffff8150bf6a RDI: ffffc90000227f48
RBP: ffffc900002301f8 R08: ffffc900002302d0 R09: ffffc900002302c8
R10: 000000000000000c R11: ffffffff8175cb90 R12: 0000000000000000
R13: ffff88810367a620 R14: ffffc90000228000 R15: ffffc90000230f40
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8e9fc64c0 CR3: 000000010c33a000 CR4: 00000000003526b0
Call Trace:
 <IRQ>
 arch_stack_walk+0x138/0x170 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:565
 unpoison_slab_object mm/kasan/common.c:321 [inline]
 __kasan_slab_alloc+0x73/0x90 mm/kasan/common.c:347
 kasan_slab_alloc include/linux/kasan.h:251 [inline]
 slab_post_alloc_hook mm/slub.c:4202 [inline]
 slab_alloc_node mm/slub.c:4251 [inline]
 kmem_cache_alloc_noprof+0x1bf/0x410 mm/slub.c:4260
 skb_clone+0x229/0x460 net/core/skbuff.c:2082
 deliver_clone net/bridge/br_forward.c:125 [inline]
 maybe_deliver net/bridge/br_forward.c:191 [inline]
 br_flood+0x4ed/0x730 net/bridge/br_forward.c:237
 br_handle_frame_finish+0x12f9/0x1760 net/bridge/br_input.c:215
 nf_hook_bridge_pre net/bridge/br_input.c:301 [inline]
 br_handle_frame+0x5a6/0xba0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xfae/0x3ab0 net/core/dev.c:5657
 __netif_receive_skb_one_core net/core/dev.c:5761 [inline]
 __netif_receive_skb net/core/dev.c:5876 [inline]
 process_backlog+0x3e5/0xad0 net/core/dev.c:6212
 __napi_poll+0xd3/0x610 net/core/dev.c:6863
 napi_poll net/core/dev.c:6932 [inline]
 net_rx_action+0x5ea/0xd80 net/core/dev.c:7054
 handle_softirqs+0x1aa/0x630 kernel/softirq.c:621
 __do_softirq+0xf/0x16 kernel/softirq.c:659
 do_softirq+0xb8/0x110 kernel/softirq.c:503
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 nocb_cb_wait kernel/rcu/tree_nocb.h:924 [inline]
 rcu_nocb_cb_kthread+0x531/0xb30 kernel/rcu/tree_nocb.h:957
 kthread+0x2c9/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
net_ratelimit: 106161 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:3e:f3:b1:e2:bb:eb, vlan:0)
net_ratelimit: 114827 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:3e:f3:b1:e2:bb:eb, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:3e:f3:b1:e2:bb:eb, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:3e:f3:b1:e2:bb:eb, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/08 09:43 android16-6.12 6aeca23b5dee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/08 00:24 android16-6.12 6aeca23b5dee 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/07 15:57 android16-6.12 6aeca23b5dee f20fc9f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/06 19:06 android16-6.12 356523087425 97745f52 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/04 13:14 android16-6.12 e92d2e0f2328 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/04 09:17 android16-6.12 a456898cc65b 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/04 01:30 android16-6.12 a456898cc65b 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/02 22:50 android16-6.12 12691bc9c3f1 d78927dd .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/02/02 15:33 android16-6.12 c13babfee861 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/30 14:01 android16-6.12 d60ccb82b419 ae7dc18c .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/29 15:27 android16-6.12 6acc5550e55c aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/28 17:16 android16-6.12 58f0d92c7966 004c195c .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/25 10:37 android16-6.12 83c6be0e1efe 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/24 21:22 android16-6.12 2f0f4b0a9a68 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
2026/01/24 19:56 android16-6.12 2f0f4b0a9a68 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_mmu_uninit_tdp_mmu
* Struck through repros no longer work on HEAD.