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INFO: task hung in bdev_open (2)

Status: premoderation: reported on 2026/05/22 08:47
Reported-by: syzbot+2133e9cef891e1395b06@syzkaller.appspotmail.com
First crash: 3d12h, last: 3d12h
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in bdev_open 1 28 95d 334d 0/1 auto-obsoleted due to no activity on 2026/05/20 08:04
upstream INFO: task hung in bdev_open prio:low block 1 C error 5313 34m 727d 0/29 upstream: reported C repro on 2024/05/28 04:10

Sample crash report:
INFO: task udevd:340 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:0     pid:340   tgid:340   ppid:110    flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6026 [inline]
 __schedule+0x14ce/0x2100 kernel/sched/core.c:7893
 __schedule_loop kernel/sched/core.c:7974 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7989
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8046
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x960/0x1bc0 kernel/locking/mutex.c:805
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 bdev_open+0xd5/0xd60 block/bdev.c:926
 blkdev_open+0x3d1/0x560 block/fops.c:627
 do_dentry_open+0x978/0x1510 fs/open.c:960
 vfs_open+0x86/0x240 fs/open.c:1092
 do_open fs/namei.c:3782 [inline]
 path_openat+0x2bb1/0x34f0 fs/namei.c:3941
 do_filp_open+0x1f5/0x440 fs/namei.c:3968
 do_sys_openat2+0x134/0x1d0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0x13a/0x170 fs/open.c:1466
 x64_sys_call+0xe69/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:258
 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: 0033:0x7f1c600a7407
RSP: 002b:00007fff5661ec30 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f1c607f0880 RCX: 00007f1c600a7407
RDX: 00000000000a0800 RSI: 00005611bf857c70 RDI: ffffffffffffff9c
RBP: 00005611bf6192c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00005611bf869b90
R13: 00005611bf85a0f0 R14: 0000000000000000 R15: 00005611bf869b90
 </TASK>
INFO: task syz.0.353:1544 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.353       state:D stack:0     pid:1544  tgid:1543  ppid:295    flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6026 [inline]
 __schedule+0x14ce/0x2100 kernel/sched/core.c:7893
 __schedule_loop kernel/sched/core.c:7974 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7989
 io_schedule+0x88/0xe0 kernel/sched/core.c:8803
 folio_wait_bit_common+0x6d8/0x950 mm/filemap.c:1356
 folio_put_wait_locked mm/filemap.c:1520 [inline]
 do_read_cache_folio+0x14d/0x4c0 mm/filemap.c:4051
 read_cache_folio+0x54/0x90 mm/filemap.c:4101
 read_mapping_folio include/linux/pagemap.h:1021 [inline]
 read_part_sector+0xcc/0x250 block/partitions/core.c:716
 msdos_partition+0x116/0x2fd0 block/partitions/msdos.c:592
 check_partition block/partitions/core.c:138 [inline]
 blk_add_partitions block/partitions/core.c:583 [inline]
 bdev_disk_changed+0x822/0x1610 block/partitions/core.c:687
 loop_reread_partitions+0x64/0x110 drivers/block/loop.c:467
 loop_configure+0x1068/0x13a0 drivers/block/loop.c:1078
 lo_ioctl+0xa8b/0x2070 drivers/block/loop.c:1520
 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+0x132/0x1b0 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: 0033:0x7f1e5b39ce59
RSP: 002b:00007f1e5c337028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1e5b615fa0 RCX: 00007f1e5b39ce59
RDX: 0000200000000140 RSI: 0000000000004c0a RDI: 0000000000000007
RBP: 00007f1e5b432d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1e5b616038 R14: 00007f1e5b615fa0 R15: 00007ffd235214e8
 </TASK>
INFO: task poweroff:1546 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:poweroff        state:D stack:0     pid:1546  tgid:1546  ppid:95     flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6026 [inline]
 __schedule+0x14ce/0x2100 kernel/sched/core.c:7893
 __schedule_loop kernel/sched/core.c:7974 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7989
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8046
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x960/0x1bc0 kernel/locking/mutex.c:805
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 sync_bdevs+0x1af/0x350 block/bdev.c:1269
 ksys_sync+0xc6/0x170 fs/sync.c:106
 __ia32_sys_sync+0x12/0x20 fs/sync.c:114
 x64_sys_call+0x2a58/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:163
 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: 0033:0x7f93e0cb2f37
RSP: 002b:00007ffcb0f2e9b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f93e0cb2f37
RDX: ffffffffffffff88 RSI: 00007f93e0e4be51 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcb0f2eb18 R14: 00007f93e0ea1000 R15: 00005605befbcd98
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 8a9cd2cbe126bd9938f6e7ac5eb01541012e42ba
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 8a9cd2cbe126bd9938f6e7ac5eb01541012e42ba
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:update_sd_lb_stats kernel/sched/fair.c:-1 [inline]
RIP: 0010:sched_balance_find_src_group kernel/sched/fair.c:11632 [inline]
RIP: 0010:sched_balance_rq+0x21da/0x4ce0 kernel/sched/fair.c:12079
Code: 40 74 0b c7 84 24 20 04 00 00 02 00 00 00 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 6c ec 7f 00 48 83 3b 00 75 5e <48> 8b 9c 24 e8 03 00 00 b8 b8 0c 00 00 48 01 c3 48 89 d8 48 c1 e8
RSP: 0018:ffffc90000007820 EFLAGS: 00000246
RAX: 1ffff1102034d900 RBX: ffff888101a6c800 RCX: ffffffff8160596e
RDX: 0000000000000018 RSI: ffffc90000007a60 RDI: ffffc90000007b10
RBP: ffffc90000007cd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000420
R13: dffffc0000000000 R14: ffff888101a6c83c R15: ffff888103a74480
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555564eb07d0 CR3: 0000000107ecc000 CR4: 00000000003526b0
DR0: 000a000000000000 DR1: ffffffffff7fff00 DR2: 0000000080000001
DR3: fffffffffffffff6 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 sched_balance_domains+0x477/0x9c0 kernel/sched/fair.c:12549
 _nohz_idle_balance+0x3fb/0x5c0 kernel/sched/fair.c:13000
 nohz_idle_balance kernel/sched/fair.c:13043 [inline]
 sched_balance_softirq+0x8a/0x170 kernel/sched/fair.c:13273
 handle_softirqs+0x1aa/0x630 kernel/softirq.c:621
 __do_softirq kernel/softirq.c:659 [inline]
 invoke_softirq kernel/softirq.c:476 [inline]
 __irq_exit_rcu+0x47/0xb0 kernel/softirq.c:708
 irq_exit_rcu+0xd/0x30 kernel/softirq.c:720
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
 sysvec_call_function_single+0x7f/0x90 arch/x86/kernel/smp.c:266
 </IRQ>
 <TASK>
 asm_sysvec_call_function_single+0x1f/0x30 arch/x86/include/asm/idtentry.h:709
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc cc cc cc cc b8 5a da d4 19 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 33 3f 3f 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:ffffffff87407da0 EFLAGS: 000002c6
RAX: ffff8881f6e00000 RBX: ffffffff874156c0 RCX: ffffffff85a81bcd
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000004e4f84
RBP: ffffffff87407da0 R08: ffff8881f6e395eb R09: 1ffff1103edc72bd
R10: dffffc0000000000 R11: ffffed103edc72be R12: 1ffffffff0e82ad8
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87ed30e8
 arch_safe_halt arch/x86/include/asm/paravirt.h:112 [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:185 [inline]
 do_idle+0x1a1/0x560 kernel/sched/idle.c:335
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:433
 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 (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/22 08:46 android16-6.12 9d40b257ba08 70ae9b03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in bdev_open
* Struck through repros no longer work on HEAD.