INFO: task hung in kvm_swap_active_memslots

Status: premoderation: reported C repro on 2026/10/23 10:17
Reported-by: syzbot+d04bab03e3541d721caf@syzkaller.appspotmail.com
First crash: 13d, last: 13d
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in kvm_swap_active_memslots kvm 1 3 581d 639d 0/29 auto-obsoleted due to no activity on 2025/07/02 12:01
upstream INFO: task hung in kvm_swap_active_memslots (2) prio:low kvm 1 syz, C 28 40d 353d 0/29 upstream: reported C repro on 2025/11/17 10:44

Sample crash report:
INFO: task syz-executor399:313 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor399 state:D stack:0     pid:313   tgid:313   ppid:312    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6068 [inline]
 __schedule+0x16fe/0x23d0 kernel/sched/core.c:7888
 __schedule_loop kernel/sched/core.c:7965 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7980
 kvm_swap_active_memslots+0x235/0x450 virt/kvm/kvm_main.c:1622
 kvm_activate_memslot virt/kvm/kvm_main.c:1766 [inline]
 kvm_create_memslot virt/kvm/kvm_main.c:1832 [inline]
 kvm_set_memslot+0x6b9/0x13a0 virt/kvm/kvm_main.c:1944
 __kvm_set_memory_region+0x7f7/0xb40 virt/kvm/kvm_main.c:2098
 kvm_set_memory_region+0x2f/0x50 virt/kvm/kvm_main.c:2119
 kvm_vm_ioctl_set_memory_region virt/kvm/kvm_main.c:2131 [inline]
 kvm_vm_ioctl+0xb01/0xc40 virt/kvm/kvm_main.c:5248
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fb261b8169b
RSP: 002b:00007ffd8e66dff0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb261b8169b
RDX: 00007ffd8e66e0b0 RSI: 000000004020ae46 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000200000c01000 R09: 0000000000005000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb261bf1b40
R13: 0000200000c06000 R14: 0000000000000000 R15: 00000000003fa000
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 ae7936ebab52aae609823c9494ba9ebab2c98923
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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:114
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:63
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 cpumask_backtrace+0x1f/0x30 lib/nmi_backtrace.c:127
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c7/0x360 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 ae7936ebab52aae609823c9494ba9ebab2c98923
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:116
Code: cc cc cc cc cc cc cc b8 c6 85 f2 d3 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 83 d9 3e 00 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90
RSP: 0018:ffffffff87c07da0 EFLAGS: 000002c2
RAX: ffff8881f6c00000 RBX: ffffffff87c156c0 RCX: ffffffff85a8853d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000002d11c
RBP: ffffffff87c07da0 R08: ffff8881f6c396fb R09: 1ffff1103ed872df
R10: dffffc0000000000 R11: ffffed103ed872e0 R12: 0000000000000000
R13: 1ffffffff0f82ad8 R14: dffffc0000000000 R15: ffffffff886da7e8
FS:  0000000000000000(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557991a398 CR3: 000000010c79c000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:-1 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3e/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:193 [inline]
 do_idle+0x1df/0x570 kernel/sched/idle.c:346
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:445
 rest_init+0x10b/0x130 init/main.c:760
 start_kernel+0x462/0x4bb init/main.c:1242
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x6a/0x7b arch/x86/kernel/head64.c:488
 common_startup_64+0x13b/0x157
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/23 16:10 android16-6.12 d3205ab6c8c7 d566bfda .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_swap_active_memslots
2026/10/23 10:16 android16-6.12 d3205ab6c8c7 d566bfda .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in kvm_swap_active_memslots
* Struck through repros no longer work on HEAD.