syzbot


INFO: task hung in blkdev_get_by_dev (2)

Status: upstream: reported on 2025/07/08 23:59
Reported-by: syzbot+db3344a4206d7ddec894@syzkaller.appspotmail.com
First crash: 53d, last: 2d09h
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in blkdev_get_by_dev origin:lts-only 1 C done 25 292d 580d 3/3 fixed on 2025/01/02 10:34
linux-5.15 INFO: task hung in blkdev_get_by_dev (2) 1 1 721d 721d 0/3 auto-obsoleted due to no activity on 2023/12/18 22:46
upstream INFO: task hung in blkdev_get_by_dev (3) block 1 1 1270d 1270d 0/29 auto-closed as invalid on 2022/05/08 09:47
linux-5.15 INFO: task hung in blkdev_get_by_dev 1 1 852d 852d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:06
linux-5.15 INFO: task hung in blkdev_get_by_dev (4) 1 3 95d 95d 0/3 upstream: reported on 2025/05/27 06:24
linux-5.15 INFO: task hung in blkdev_get_by_dev (3) 1 17 356d 577d 0/3 auto-obsoleted due to no activity on 2024/12/17 17:06
upstream INFO: task hung in blkdev_get_by_dev fs 1 1 1650d 1650d 0/29 auto-closed as invalid on 2021/05/23 22:12
upstream INFO: task hung in blkdev_get_by_dev (4) block 1 1 1099d 1099d 0/29 auto-obsoleted due to no activity on 2022/11/25 11:03
linux-6.6 INFO: task hung in blkdev_get_by_dev origin:upstream 1 C 7 10d 70d 0/2 upstream: reported C repro on 2025/06/21 06:39
upstream INFO: task hung in blkdev_get_by_dev (2) block 1 1727 1302d 1382d 0/29 closed as dup on 2021/11/21 14:02
upstream INFO: task hung in blkdev_get_by_dev (5) block 1 C error error 32 140d 912d 0/29 upstream: reported C repro on 2023/03/02 18:11

Sample crash report:
INFO: task syz.0.518:5891 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.518       state:D stack:27776 pid:5891  ppid:4267   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
 blkdev_get_by_dev+0x13d/0xa60 block/bdev.c:815
 blkdev_open+0x11e/0x2e0 block/fops.c:500
 do_dentry_open+0x7e9/0x10d0 fs/open.c:882
 do_open fs/namei.c:3626 [inline]
 path_openat+0x25c6/0x2e70 fs/namei.c:3783
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
 do_sys_openat2+0x142/0x490 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1345
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7a9458d550
RSP: 002b:00007f7a9531eb70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080000 RCX: 00007f7a9458d550
RDX: 0000000000080000 RSI: 00007f7a9531ec10 RDI: 00000000ffffff9c
RBP: 00007f7a9531ec10 R08: 0000000000000000 R09: 002364626e2f7665
R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
R13: 00007f7a947b6038 R14: 00007f7a947b5fa0 R15: 00007ffda319f9f8
 </TASK>
INFO: task syz.0.518:5894 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.518       state:D stack:28960 pid:5894  ppid:4267   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
 blkdev_get_by_dev+0x13d/0xa60 block/bdev.c:815
 blkdev_get_by_path+0x1d6/0x3f0 block/bdev.c:889
 mount_bdev+0x4a/0x3c0 fs/super.c:1399
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:632
 vfs_get_tree+0x88/0x270 fs/super.c:1573
 do_new_mount+0x24a/0xa40 fs/namespace.c:3069
 do_mount fs/namespace.c:3412 [inline]
 __do_sys_mount fs/namespace.c:3620 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3597
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7a9458ebe9
RSP: 002b:00007f7a927f6038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f7a947b6090 RCX: 00007f7a9458ebe9
RDX: 0000200000000080 RSI: 0000200000004a00 RDI: 0000200000000000
RBP: 00007f7a94611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002008087 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7a947b6128 R14: 00007f7a947b6090 R15: 00007ffda319f9f8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2b370 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2bb90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2a9e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by getty/4030:
 #0: ffff88802fd43098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
1 lock held by udevd/4494:
 #0: ffff8880248ef4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x13d/0xa60 block/bdev.c:815
1 lock held by syz.0.518/5891:
 #0: ffff8880248ef4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x13d/0xa60 block/bdev.c:815
1 lock held by syz.0.518/5894:
 #0: ffff8880248ef4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x13d/0xa60 block/bdev.c:815
5 locks held by kworker/1:17/7015:
 #0: ffff88801d6fb538 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000d94fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
 #2: ffff888027bdb190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #2: ffff888027bdb190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1a7/0x54e0 drivers/usb/core/hub.c:5845
 #3: ffff88807511d190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #3: ffff88807511d190 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x460 drivers/base/dd.c:990
 #4: ffff88805ec6f118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #4: ffff88805ec6f118 (&dev->mutex){....}-{3:3}, at: __device_attach+0x85/0x460 drivers/base/dd.c:990

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4350 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: phy13 ieee80211_iface_work
RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:360 [inline]
RIP: 0010:unwind_next_frame+0xb21/0x20b0 arch/x86/kernel/unwind_orc.c:539
Code: c0 20 c8 3c 01 0f 85 9f 0d 00 00 48 89 ef e8 16 1f 00 00 49 89 c7 49 bd 00 00 00 00 00 fc ff df 48 8b 44 24 28 42 80 3c 28 00 <4c> 8b 74 24 08 74 08 4c 89 f7 e8 50 7d 98 00 4d 89 3e 48 8b 44 24
RSP: 0018:ffffc900049a75f0 EFLAGS: 00000246
RAX: 1ffff92000934ee2 RBX: ffffc900049a76c8 RCX: 1ffff92000934e01
RDX: ffffc900049a7bc8 RSI: ffffffff8e7f35b0 RDI: ffffc900049a7bc0
RBP: ffffc900049a7bc0 R08: 000000000000000f R09: 0000000000000006
R10: fffff52000934ee5 R11: 1ffff92000934ee3 R12: 1ffff92000934eda
R13: dffffc0000000000 R14: ffffc900049a0000 R15: ffffffff89937c03
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32d23ffc CR3: 000000000c88e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3674
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5db/0x7c0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 kfree_skb_reason+0x163/0x370 net/core/skbuff.c:893
 kfree_skb include/linux/skbuff.h:1220 [inline]
 ieee80211_iface_work+0x7b3/0xc80 net/mac80211/iface.c:1727
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/28 18:02 linux-6.1.y f89b6e15694c e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in blkdev_get_by_dev
2025/08/19 15:34 linux-6.1.y 0bc96de781b4 254a27c1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in blkdev_get_by_dev
2025/07/08 23:58 linux-6.1.y 04d1ccaa9c28 4d9fdfa4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in blkdev_get_by_dev
* Struck through repros no longer work on HEAD.