syzbot


INFO: task hung in find_inode_fast (2)

Status: upstream: reported syz repro on 2025/04/17 13:02
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+86129b61506f3a4600ee@syzkaller.appspotmail.com
First crash: 30d, last: 23d
Bug presence (2)
Date Name Commit Repro Result
2025/04/24 linux-6.1.y (ToT) 420102835862 C [report] INFO: task hung in find_inode_fast
2025/04/24 upstream (ToT) a79be02bba5c C Didn't crash
Similar bugs (8)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in find_inode_fast (3) 1 45d 45d 0/3 upstream: reported on 2025/04/02 13:08
upstream INFO: task hung in find_inode_fast (4) ext4 syz error 9 10d 146d 0/28 upstream: reported syz repro on 2024/12/23 01:23
upstream INFO: task hung in find_inode_fast (3) ext4 7 278d 376d 0/28 auto-obsoleted due to no activity on 2024/11/10 11:05
upstream INFO: task hung in find_inode_fast (2) ext4 C unreliable done 10 520d 674d 25/28 fixed on 2024/01/30 15:47
linux-5.15 INFO: task hung in find_inode_fast 3 738d 756d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:07
upstream INFO: task hung in find_inode_fast ext4 C error 28 711d 861d 22/28 fixed on 2023/06/08 14:41
linux-6.1 INFO: task hung in find_inode_fast 1 178d 178d 0/3 auto-obsoleted due to no activity on 2025/02/28 14:47
linux-5.15 INFO: task hung in find_inode_fast (2) 1 197d 197d 0/3 auto-obsoleted due to no activity on 2025/02/09 11:15
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/04/26 05:52 20m fix candidate upstream error job log

Sample crash report:
INFO: task syz.2.1106:8809 blocked for more than 143 seconds.
      Not tainted 6.1.134-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1106      state:D stack:24152 pid:8809  ppid:4377   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 __wait_on_freeing_inode fs/inode.c:2286 [inline]
 find_inode_fast+0x315/0x450 fs/inode.c:995
 iget_locked+0xc7/0x830 fs/inode.c:1360
 __ext4_iget+0x25d/0x3ee0 fs/ext4/inode.c:4831
 ext4_xattr_inode_cache_find fs/ext4/xattr.c:1499 [inline]
 ext4_xattr_inode_lookup_create+0x510/0x1ff0 fs/ext4/xattr.c:1538
 ext4_xattr_block_set+0x26b/0x3820 fs/ext4/xattr.c:1867
 ext4_xattr_set_handle+0xdac/0x1560 fs/ext4/xattr.c:2404
 ext4_xattr_set+0x26e/0x3d0 fs/ext4/xattr.c:2506
 __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
 __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
 vfs_setxattr+0x21d/0x420 fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x250/0x2b0 fs/xattr.c:617
 path_setxattr+0x1bc/0x2a0 fs/xattr.c:636
 __do_sys_setxattr fs/xattr.c:652 [inline]
 __se_sys_setxattr fs/xattr.c:648 [inline]
 __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:648
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f25d198e169
RSP: 002b:00007f25d2879038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f25d1bb5fa0 RCX: 00007f25d198e169
RDX: 0000200000001400 RSI: 00002000000001c0 RDI: 0000200000000200
RBP: 00007f25d1a10a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000835 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f25d1bb5fa0 R15: 00007ffd6968bc98
 </TASK>
INFO: task syz.2.1106:8820 blocked for more than 143 seconds.
      Not tainted 6.1.134-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1106      state:D stack:26360 pid:8820  ppid:4377   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 mb_cache_entry_wait_unused+0x162/0x240 fs/mbcache.c:148
 ext4_evict_ea_inode+0x146/0x2e0 fs/ext4/xattr.c:444
 ext4_evict_inode+0x19d/0x1150 fs/ext4/inode.c:181
 evict+0x529/0x930 fs/inode.c:705
 ext4_xattr_set_entry+0x183a/0x1fa0 fs/ext4/xattr.c:1798
 ext4_xattr_block_set+0x1a92/0x3820 fs/ext4/xattr.c:1910
 ext4_xattr_set_handle+0x1043/0x1560 fs/ext4/xattr.c:2395
 ext4_xattr_set+0x26e/0x3d0 fs/ext4/xattr.c:2506
 __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
 __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
 vfs_setxattr+0x21d/0x420 fs/xattr.c:309
 do_setxattr fs/xattr.c:594 [inline]
 setxattr+0x250/0x2b0 fs/xattr.c:617
 path_setxattr+0x1bc/0x2a0 fs/xattr.c:636
 __do_sys_setxattr fs/xattr.c:652 [inline]
 __se_sys_setxattr fs/xattr.c:648 [inline]
 __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:648
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f25d198e169
RSP: 002b:00007f25d2858038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f25d1bb6080 RCX: 00007f25d198e169
RDX: 0000200000000080 RSI: 0000200000000180 RDI: 00002000000000c0
RBP: 00007f25d1a10a68 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000032 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f25d1bb6080 R15: 00007ffd6968bc98
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d32e910 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d32f110 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6510
1 lock held by udevd/3623:
1 lock held by dhcpcd/3917:
 #0: ffffffff8e550d68 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x29a/0x1ae0 net/ipv4/devinet.c:1081
2 locks held by getty/4006:
 #0: ffff88803100f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000325e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x54a/0x1620 drivers/tty/n_tty.c:2198
2 locks held by syz-execprog/4277:
 #0: ffff8880b8f3a998 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
 #1: ffff8880b8f27788 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x419/0x790 kernel/sched/psi.c:999
4 locks held by kworker/u4:1/4305:
 #0: ffff888017e16938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000455fd20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8e544210 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x166/0xd20 net/core/net_namespace.c:594
 #3: ffffffff8e550d68 (rtnl_mutex){+.+.}-{3:3}, at: ip6_tnl_exit_batch_net+0xc0/0x610 net/ipv6/ip6_tunnel.c:2294
4 locks held by kworker/u4:3/4309:
 #0: ffff888017c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000451fd20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8e550d68 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
 #3: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #3: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4f0/0x930 kernel/rcu/tree_exp.h:962
2 locks held by kworker/0:5/4328:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000462fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
2 locks held by kworker/0:6/4331:
 #0: ffff888017c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000469fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
3 locks held by kworker/0:9/4336:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000447fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #2: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x930 kernel/rcu/tree_exp.h:962
2 locks held by kworker/0:10/4415:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc90003497d20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
3 locks held by syz.2.1106/8809:
 #0: ffff888069bd4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
 #1: ffff888068e05440 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888068e05440 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x1dd/0x420 fs/xattr.c:308
 #2: ffff888068e05108 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff888068e05108 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x270/0x1560 fs/ext4/xattr.c:2319
3 locks held by syz.2.1106/8820:
 #0: ffff888069bd4460 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
 #1: ffff888055d03628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888055d03628 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_setxattr+0x1dd/0x420 fs/xattr.c:308
 #2: ffff888055d032f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff888055d032f0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x270/0x1560 fs/ext4/xattr.c:2319
1 lock held by syz-executor/16028:
 #0: ffffffff8e550d68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e550d68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7cb/0x1000 net/core/rtnetlink.c:6150

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.1.134-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1ca/0x430 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+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 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: 3605 Comm: syslogd Not tainted 6.1.134-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__bfs kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__bfs_backwards kernel/locking/lockdep.c:1842 [inline]
RIP: 0010:check_irq_usage kernel/locking/lockdep.c:2782 [inline]
RIP: 0010:check_prev_add kernel/locking/lockdep.c:3094 [inline]
RIP: 0010:check_prevs_add kernel/locking/lockdep.c:3209 [inline]
RIP: 0010:validate_chain+0x1dc0/0x5950 kernel/locking/lockdep.c:3825
Code: e1 ff 0f 00 00 89 0d 63 68 c5 11 2b 05 59 68 c5 11 25 ff 0f 00 00 39 05 8e 47 c0 0f 73 06 89 05 86 47 c0 0f 45 31 ed 4c 89 f8 <48> c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 0f 84 27 ff
RSP: 0018:ffffc90002f86f40 EFLAGS: 00000046
RAX: ffffffff93ba88c8 RBX: ffffffff933034b8 RCX: 000000000000018c
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90c5b5f0
RBP: ffffc90002f871f0 R08: dffffc0000000000 R09: fffffbfff225704d
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffffff93bbd8c8
R13: 0000000000000000 R14: ffffffff90c5b5d0 R15: ffffffff93ba88c8
FS:  00007f43e6ad6380(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f1375a5000 CR3: 000000007fb70000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 update_cfs_rq_load_avg kernel/sched/fair.c:4027 [inline]
 update_load_avg+0x210/0x1540 kernel/sched/fair.c:4186
 enqueue_entity+0x11c/0x1770 kernel/sched/fair.c:4772
 enqueue_task_fair+0x228/0xb80 kernel/sched/fair.c:6120
 enqueue_task+0x19d/0x2e0 kernel/sched/core.c:2059
 activate_task kernel/sched/core.c:2087 [inline]
 ttwu_do_activate+0x1b4/0x370 kernel/sched/core.c:3699
 ttwu_queue kernel/sched/core.c:3904 [inline]
 try_to_wake_up+0x6f6/0x1250 kernel/sched/core.c:4227
 autoremove_wake_function+0x12/0x110 kernel/sched/wait.c:419
 __wake_up_common+0x2a0/0x4e0 kernel/sched/wait.c:107
 __wake_up_common_lock kernel/sched/wait.c:138 [inline]
 __wake_up_sync_key+0x114/0x1c0 kernel/sched/wait.c:208
 __unix_dgram_recvmsg+0x5ff/0x12c0 net/unix/af_unix.c:2454
 sock_recvmsg_nosec net/socket.c:1022 [inline]
 sock_recvmsg net/socket.c:1040 [inline]
 sock_read_iter+0x3b2/0x4b0 net/socket.c:1121
 call_read_iter include/linux/fs.h:2259 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x88d/0xbf0 fs/read_write.c:470
 ksys_read+0x19c/0x2c0 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f43e6c2ab6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff473b1e18 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f43e6c2ab6a
RDX: 00000000000000ff RSI: 000056208baa3950 RDI: 0000000000000000
RBP: 000056208baa3910 R08: 0000000000000001 R09: 0000000000000000
R10: 00007f43e6dc93a3 R11: 0000000000000246 R12: 000056208baa398b
R13: 000056208baa3950 R14: 0000000000000000 R15: 00007f43e6e07a80
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/19 22:45 linux-6.1.y 420102835862 2a20f901 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-6-1-kasan INFO: task hung in find_inode_fast
2025/04/17 13:01 linux-6.1.y 420102835862 229db4cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in find_inode_fast
* Struck through repros no longer work on HEAD.