syzbot


INFO: task hung in kvm_swap_active_memslots

Status: auto-obsoleted due to no activity on 2025/07/02 12:01
Subsystems: kvm
[Documentation on labels]
First crash: 180d, last: 122d

Sample crash report:
INFO: task syz.3.71:6254 blocked for more than 143 seconds.
      Not tainted 6.14.0-syzkaller-12886-ga1b5bd45d4ee #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.71        state:D stack:26120 pid:6254  tgid:6237  ppid:5836   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 kvm_swap_active_memslots+0x2ea/0x7d0 virt/kvm/kvm_main.c:1576
 kvm_activate_memslot virt/kvm/kvm_main.c:1720 [inline]
 kvm_create_memslot virt/kvm/kvm_main.c:1786 [inline]
 kvm_set_memslot+0xd3b/0x1380 virt/kvm/kvm_main.c:1898
 kvm_set_memory_region+0xeaf/0x1690 virt/kvm/kvm_main.c:2054
 kvm_set_internal_memslot+0x9f/0xe0 virt/kvm/kvm_main.c:2077
 __x86_set_memory_region+0x2f6/0x740 arch/x86/kvm/x86.c:12846
 kvm_alloc_apic_access_page+0x9e/0x110 arch/x86/kvm/lapic.c:2691
 vmx_vcpu_create+0x5e4/0xd00 arch/x86/kvm/vmx/vmx.c:7649
 kvm_arch_vcpu_create+0x655/0xac0 arch/x86/kvm/x86.c:12332
 kvm_vm_ioctl_create_vcpu virt/kvm/kvm_main.c:4124 [inline]
 kvm_vm_ioctl+0xf25/0x3d40 virt/kvm/kvm_main.c:5070
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x190/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe55058d169
RSP: 002b:00007fe55136d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe5507a6160 RCX: 00007fe55058d169
RDX: 0000000000000038 RSI: 000000000000ae41 RDI: 0000000000000003
RBP: 00007fe55060e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe5507a6160 R15: 00007ffd56eeb728
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c1580 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c1580 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e3c1580 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6764
2 locks held by syz.3.71/6254:
 #0: ffffc9000bf510a8 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_alloc_apic_access_page+0x27/0x110 arch/x86/kvm/lapic.c:2686
 #1: ffffc9000bf51138 (&kvm->slots_arch_lock){+.+.}-{4:4}, at: kvm_set_memslot+0x34/0x1380 virt/kvm/kvm_main.c:1849
1 lock held by syz-executor/6491:
2 locks held by syz-executor/6731:
 #0: ffff8880b8439f18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:605
 #1: ffff8880b8423c48 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2c1/0x8e0 kernel/sched/psi.c:987
1 lock held by syz-executor/6754:
 #0: ffffffff9012bd68 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff9012bd68 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x230 drivers/net/tun.c:3390
4 locks held by kworker/u8:21/7474:
 #0: ffff88801c2f6148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc9000433fd18 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffffffff90115ed0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xc9/0xb30 net/core/net_namespace.c:608
 #3: ffffffff9012bd68 (rtnl_mutex){+.+.}-{4:4}, at: netdev_wait_allrefs_any net/core/dev.c:11178 [inline]
 #3: ffffffff9012bd68 (rtnl_mutex){+.+.}-{4:4}, at: netdev_run_todo+0xe33/0x1320 net/core/dev.c:11298
2 locks held by getty/8131:
 #0: ffff8880324cc0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000e8c32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by syz.0.475/8378:
1 lock held by syz.4.500/8596:
2 locks held by syz.2.502/8581:
 #0: ffffffff90115ed0 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x286/0x5f0 net/core/net_namespace.c:514
 #1: ffffffff9012bd68 (rtnl_mutex){+.+.}-{4:4}, at: setup_net+0x3f9/0x850 net/core/net_namespace.c:386
1 lock held by dhcpcd/8615:
 #0: ffff8880355b2258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1615 [inline]
 #0: ffff8880355b2258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf60 net/packet/af_packet.c:3252
1 lock held by dhcpcd/8616:
 #0: ffff888079a74258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1615 [inline]
 #0: ffff888079a74258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf60 net/packet/af_packet.c:3252
1 lock held by dhcpcd/8617:
 #0: ffff888063012258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1615 [inline]
 #0: ffff888063012258 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf60 net/packet/af_packet.c:3252

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-syzkaller-12886-ga1b5bd45d4ee #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xf70/0x12c0 kernel/hung_task.c:437
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/03 11:55 upstream a1b5bd45d4ee 996a9618 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in kvm_swap_active_memslots
2025/02/06 06:39 upstream 92514ef226f5 577d049b .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in kvm_swap_active_memslots
2025/02/04 09:34 upstream 0de63bb7d919 8f267cef .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: task hung in kvm_swap_active_memslots
* Struck through repros no longer work on HEAD.