syzbot


INFO: task hung in blkdev_put

Status: upstream: reported C repro on 2025/07/23 11:17
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+810a82ba4601be510bde@syzkaller.appspotmail.com
First crash: 10d, last: 7d04h
Bug presence (1)
Date Name Commit Repro Result
2025/07/26 upstream (ToT) 302f88ff3584 C [report] INFO: task hung in bdev_release
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in blkdev_put (3) fs 1 1 1924d 1924d 0/29 auto-closed as invalid on 2020/06/25 13:28
android-49 INFO: task hung in blkdev_put (2) 1 3 2087d 2106d 0/3 auto-closed as invalid on 2020/03/14 12:22
linux-4.19 INFO: task hung in blkdev_put 1 C error 31 1071d 1835d 0/1 upstream: reported C repro on 2020/07/23 21:33
upstream INFO: task hung in blkdev_put udf 1 320 2365d 2792d 0/29 closed as dup on 2018/11/11 08:29
linux-4.14 INFO: task hung in blkdev_put 1 2 2149d 2298d 0/1 auto-closed as invalid on 2020/01/12 01:56
linux-5.15 INFO: task hung in blkdev_put origin:upstream 1 C error 5 399d 771d 0/3 upstream: reported C repro on 2023/06/23 01:15
linux-4.14 INFO: task hung in blkdev_put (3) 1 C error 16 1019d 1797d 0/1 upstream: reported C repro on 2020/08/30 21:52
upstream INFO: task hung in blkdev_put (4) block 1 C done error 486 507d 1764d 0/29 upstream: reported C repro on 2020/10/03 13:09
android-49 INFO: task hung in blkdev_put 1 220 2285d 2302d 0/3 auto-closed as invalid on 2019/10/25 08:47
linux-4.14 INFO: task hung in blkdev_put (2) 1 2 1952d 1991d 0/1 auto-closed as invalid on 2020/07/26 14:38
android-414 INFO: task hung in blkdev_put 1 119 2071d 2303d 0/1 auto-closed as invalid on 2020/03/30 04:06
android-44 INFO: task hung in blkdev_put 1 26 2371d 2302d 0/2 auto-closed as invalid on 2019/08/03 02:42
android-44 INFO: task hung in blkdev_put (2) 1 3 2082d 2159d 0/2 auto-closed as invalid on 2020/03/18 19:27
linux-6.1 INFO: task hung in blkdev_put origin:upstream 1 C 227 21d 830d 0/3 upstream: reported C repro on 2023/04/25 09:01
upstream INFO: task hung in blkdev_put (2) fs 1 2 2078d 2124d 0/29 auto-closed as invalid on 2020/02/22 04:07

Sample crash report:
INFO: task syz.0.31:5974 blocked for more than 143 seconds.
      Not tainted 6.6.100-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.31        state:D stack:27912 pid:5974  ppid:5896   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6833
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 blkdev_put+0xff/0x760 block/bdev.c:927
 blkdev_release+0x84/0x90 block/fops.c:604
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 get_signal+0x1235/0x1400 kernel/signal.c:2678
 arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f131d98e9a9
RSP: 002b:00007f131e76a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007f131dbb5fa0 RCX: 00007f131d98e9a9
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007f131da10d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f131dbb5fa0 R15: 00007fffed10f7f8
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/1:1/27:
 #0: ffff8880b8f3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
 #1: ffff8880b8f288c8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x316/0x6d0 kernel/sched/psi.c:986
 #2: ffff8880b8f295a8 (krc.lock){..-.}-{2:2}, at: kvfree_rcu_bulk+0x214/0x470 kernel/rcu/tree.c:3044
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2fba0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
1 lock held by syslogd/5139:
 #0: ffff8880b8f3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
1 lock held by klogd/5146:
 #0: ffff8880b8f3c458 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
2 locks held by getty/5546:
 #0: ffff888031dea0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by udevd/5804:
 #0: ffff8881417254c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:788
1 lock held by udevd/5852:
 #0: ffff888021dbb4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:788
1 lock held by syz.0.31/5974:
 #0: ffff8881417254c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xff/0x760 block/bdev.c:927
1 lock held by syz.1.142/6235:
 #0: ffff888021dbb4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xff/0x760 block/bdev.c:927
1 lock held by udevd/6239:
 #0: ffff888021e004c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:788
1 lock held by syz.2.157/6292:
 #0: ffff888021e004c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xff/0x760 block/bdev.c:927

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.6.100-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 59 Comm: kworker/u4:4 Not tainted 6.6.100-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:unwind_next_frame+0x1c55/0x2970 arch/x86/kernel/unwind_orc.c:665
Code: 0f 85 a3 0a 00 00 41 8b 2c 24 89 ef 44 8b b4 24 8c 00 00 00 44 89 f6 e8 f9 d7 4a 00 44 39 f5 0f 85 a1 00 00 00 48 8b 44 24 68 <42> 80 3c 28 00 74 08 48 89 df e8 5c 1c a2 00 4d 8b 74 24 38 49 8d
RSP: 0018:ffffc900015a6d38 EFLAGS: 00000246
RAX: 1ffff920002b4dc8 RBX: ffffc900015a6e40 RCX: 0000000000000000
RDX: ffff88801f2a8000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000001 R08: ffff88801f2a8000 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc900015a6e08
R13: dffffc0000000000 R14: 0000000000000001 R15: ffffffff8f5fd78c
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0083c4000 CR3: 0000000030dba000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 kvfree_call_rcu+0xee/0x780 kernel/rcu/tree.c:3452
 cfg80211_update_known_bss+0x172/0x900 net/wireless/scan.c:-1
 __cfg80211_bss_update+0x144/0x21f0 net/wireless/scan.c:1871
 cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2981 [inline]
 cfg80211_inform_bss_frame_data+0xaea/0x12b0 net/wireless/scan.c:3012
 ieee80211_bss_info_update+0x70b/0x930 net/mac80211/scan.c:211
 ieee80211_rx_bss_info net/mac80211/ibss.c:1124 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1613 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x17c9/0x2ac0 net/mac80211/ibss.c:1642
 ieee80211_iface_process_skb net/mac80211/iface.c:1643 [inline]
 ieee80211_iface_work+0x717/0xc70 net/mac80211/iface.c:1697
 cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/26 09:18 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in blkdev_put
2025/07/26 06:25 linux-6.6.y dbcb8d8e4163 fb8f743d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in blkdev_put
2025/07/23 11:17 linux-6.6.y d96eb99e2f0e e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in blkdev_put
* Struck through repros no longer work on HEAD.