INFO: task hung in blk_freeze_queue (2)

Status: premoderation: reported on 2026/08/15 07:37
Reported-by: syzbot+066626c9d06f50bbdd76@syzkaller.appspotmail.com
First crash: 9d09h, last: 2d08h
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in blk_freeze_queue (4) block 1 2 1213d 1215d 0/29 auto-obsoleted due to no activity on 2023/07/28 15:48
upstream INFO: task hung in blk_freeze_queue block 1 syz, C 188 2969d 3120d 8/29 fixed on 2018/07/09 18:05
upstream INFO: task hung in blk_freeze_queue (3) arm 1 syz, C 8 1374d 1454d 22/29 fixed on 2023/02/24 13:50
upstream INFO: task hung in blk_freeze_queue (5) block 1 1 878d 878d 0/29 auto-obsoleted due to no activity on 2024/06/27 12:04
upstream INFO: task hung in blk_freeze_queue (2) block 1 1 2871d 2871d 0/29 auto-closed as invalid on 2019/04/12 00:55
linux-6.1 INFO: task hung in blk_freeze_queue origin:upstream 1 syz, C error 1 713d 1173d 0/3 upstream: reported C repro on 2023/06/08 14:42
android-6-12 INFO: task hung in blk_freeze_queue 1 1 401d 401d 0/1 auto-obsoleted due to no activity on 2025/10/17 10:06

Sample crash report:
INFO: task syz.0.201:934 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.201       state:D stack:0     pid:934   tgid:931   ppid:299    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6060 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7880
 __schedule_loop kernel/sched/core.c:7957 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7972
 blk_mq_freeze_queue_wait+0xf3/0x180 block/blk-mq.c:210
 blk_freeze_queue+0xc7/0x100 block/blk-mq.c:237
 blk_mq_freeze_queue+0x19/0x30 block/blk-mq.c:246
 loop_change_fd drivers/block/loop.c:581 [inline]
 lo_ioctl+0x1ac1/0x2010 drivers/block/loop.c:1523
 blkdev_ioctl+0x548/0x690 block/ioctl.c:699
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x135/0x1b0 fs/ioctl.c:893
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:893
 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: 0033:0x7fb8f439e0d9
RSP: 002b:00007fb8f518f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb8f4626090 RCX: 00007fb8f439e0d9
RDX: 0000000000000002 RSI: 0000000000004c06 RDI: 0000000000000000
RBP: 00007fb8f4435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb8f4626128 R14: 00007fb8f4626090 R15: 00007ffddb59bfc8
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 9a2c17613351c9eac8e18d74829f474689ac6bc1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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+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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 9a2c17613351c9eac8e18d74829f474689ac6bc1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:116
Code: cc cc cc cc cc cc cc b8 4a 0d 8a 82 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 23 b9 42 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:ffffc900001a7e00 EFLAGS: 000002c2
RAX: ffff8881f6f00000 RBX: ffff888103669300 RCX: ffffffff85a4a4fd
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000002da834
RBP: ffffc900001a7e00 R08: ffff8881f6f395eb R09: 1ffff1103ede72bd
R10: dffffc0000000000 R11: ffffed103ede72be R12: 0000000000000000
R13: 1ffff110206cd260 R14: dffffc0000000000 R15: ffffffff87ecc9a8
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2650e3 CR3: 000000010272c000 CR4: 00000000003526b0
DR0: 0000000000007b35 DR1: 0000000000008001 DR2: 7fffffffffffffff
DR3: 0000000000000003 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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+0x2fc/0x570 kernel/sched/idle.c:346
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:445
 start_secondary+0x12e/0x140 arch/x86/kernel/smpboot.c:314
 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
2026/08/22 09:07 android16-6.12 e8c85685a629 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in blk_freeze_queue
2026/08/15 07:36 android16-6.12 26014f6c6077 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in blk_freeze_queue
* Struck through repros no longer work on HEAD.