syzbot


INFO: task hung in bfs_lookup (2)

Status: auto-obsoleted due to no activity on 2024/01/21 21:34
Subsystems: bfs
[Documentation on labels]
First crash: 240d, last: 196d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in bfs_lookup 1 515d 515d 0/1 auto-obsoleted due to no activity on 2023/04/07 07:53
upstream INFO: task hung in bfs_lookup bfs 1 385d 385d 0/26 auto-obsoleted due to no activity on 2023/07/17 03:03

Sample crash report:
INFO: task syz-executor.1:5478 blocked for more than 143 seconds.
      Not tainted 6.6.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1  state:D stack:27528 pid:5478  ppid:5076   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x196c/0x4af0 kernel/sched/core.c:6695
 schedule+0xc3/0x180 kernel/sched/core.c:6771
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6830
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6a3/0xd60 kernel/locking/mutex.c:747
 bfs_lookup+0x139/0x270 fs/bfs/dir.c:136
 lookup_open fs/namei.c:3474 [inline]
 open_last_lookups fs/namei.c:3564 [inline]
 path_openat+0x11f1/0x3180 fs/namei.c:3794
 do_filp_open+0x234/0x490 fs/namei.c:3824
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x247/0x290 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fe07f27cae9
RSP: 002b:00007fe0800030c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe07f39c120 RCX: 00007fe07f27cae9
RDX: 0000000000000180 RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007fe07f2c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fe07f39c120 R15: 00007ffcd8b04c68
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8d32c460 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:303 [inline]
 #0: ffffffff8d32c460 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:749 [inline]
 #0: ffffffff8d32c460 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6613
2 locks held by getty/4790:
 #0: ffff88802a5c20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b1/0x1dc0 drivers/tty/n_tty.c:2206
5 locks held by syz-executor.4/5072:
3 locks held by syz-executor.1/5461:
2 locks held by syz-executor.1/5478:
 #0: ffff88803387c168 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:812 [inline]
 #0: ffff88803387c168 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: open_last_lookups fs/namei.c:3563 [inline]
 #0: ffff88803387c168 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: path_openat+0x7b3/0x3180 fs/namei.c:3794
 #1: ffff88807451fed8 (&info->bfs_lock){+.+.}-{3:3}, at: bfs_lookup+0x139/0x270 fs/bfs/dir.c:136

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

NMI backtrace for cpu 0
CPU: 0 PID: 30 Comm: khungtaskd Not tainted 6.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x498/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x310 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+0xfa9/0xff0 kernel/hung_task.c:379
 kthread+0x2d3/0x370 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 48 Comm: kworker/u4:3 Not tainted 6.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: bat_events batadv_nc_worker
RIP: 0010:mark_lock+0xe7/0x340 kernel/locking/lockdep.c:4655
Code: e8 03 42 0f b6 04 28 84 c0 0f 85 0f 02 00 00 83 3d 7d ed 7f 10 00 74 39 31 db 48 83 c3 60 48 89 d8 48 c1 e8 03 42 80 3c 28 00 <74> 08 48 89 df e8 1f e7 7a 00 41 bc 01 00 00 00 44 85 33 74 53 44
RSP: 0018:ffffc90000b8f938 EFLAGS: 00000046
RAX: 1ffffffff208264c RBX: ffffffff90413260 RCX: ffffffff816dd56a
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff906e4458
RBP: 0000000000000002 R08: ffffffff906e445f R09: 1ffffffff20dc88b
R10: dffffc0000000000 R11: fffffbfff20dc88c R12: ffff888019256450
R13: dffffc0000000000 R14: 0000000000000004 R15: ffff888019256430
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005570d4585ef8 CR3: 000000000d130000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 mark_held_locks kernel/locking/lockdep.c:4273 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:4291 [inline]
 lockdep_hardirqs_on_prepare+0x281/0x7a0 kernel/locking/lockdep.c:4358
 trace_hardirqs_on+0x28/0x40 kernel/trace/trace_preemptirq.c:61
 __local_bh_enable_ip+0x168/0x1f0 kernel/softirq.c:386
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 batadv_nc_purge_paths+0x309/0x3a0 net/batman-adv/network-coding.c:471
 batadv_nc_worker+0x328/0x610 net/batman-adv/network-coding.c:720
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703
 worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784
 kthread+0x2d3/0x370 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/10/23 21:26 upstream 05d3ef8bba77 989a3687 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in bfs_lookup
2023/09/09 22:36 upstream 6099776f9f26 6654cf89 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in bfs_lookup
* Struck through repros no longer work on HEAD.