syzbot


INFO: task hung in find_inode_fast (4)

Status: upstream: reported syz repro on 2024/12/23 01:23
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+fd5533bcd0f7343bb8ca@syzkaller.appspotmail.com
First crash: 192d, last: 49d
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] INFO: task hung in find_inode_fast (4) 0 (1) 2024/12/23 01:23
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 85d 85d 0/3 upstream: reported on 2025/04/02 13:08
upstream INFO: task hung in find_inode_fast (3) ext4 7 318d 415d 0/29 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 560d 713d 25/29 fixed on 2024/01/30 15:47
linux-5.15 INFO: task hung in find_inode_fast 3 777d 795d 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 751d 900d 22/29 fixed on 2023/06/08 14:41
linux-6.1 INFO: task hung in find_inode_fast (2) origin:lts-only syz error 2 63d 70d 0/3 upstream: reported syz repro on 2025/04/17 13:02
linux-6.1 INFO: task hung in find_inode_fast 1 217d 217d 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 237d 237d 0/3 auto-obsoleted due to no activity on 2025/02/09 11:15
Last patch testing requests (4)
Created Duration User Patch Repo Result
2025/06/17 08:22 22m retest repro linux-next OK log
2025/04/07 16:57 43m retest repro linux-next error
2025/03/24 06:17 31m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci OK log
2025/01/26 19:12 1h02m retest repro linux-next error

Sample crash report:
INFO: task syz.0.301:7443 blocked for more than 142 seconds.
      Not tainted 6.15.0-rc5-syzkaller-00038-g707df3375124 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.301       state:D stack:27016 pid:7443  tgid:7426  ppid:5822   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6860
 __wait_on_freeing_inode+0x1c5/0x2f0 fs/inode.c:2454
 find_inode_fast+0x2b0/0x470 fs/inode.c:1070
 iget_locked+0x99/0x570 fs/inode.c:1427
 __ext4_iget+0x245/0x3e30 fs/ext4/inode.c:4800
 ext4_xattr_inode_cache_find fs/ext4/xattr.c:1540 [inline]
 ext4_xattr_inode_lookup_create+0x433/0x1c20 fs/ext4/xattr.c:1579
 ext4_xattr_block_set+0x223/0x2ac0 fs/ext4/xattr.c:1908
 ext4_xattr_set_handle+0xdfb/0x1590 fs/ext4/xattr.c:2447
 ext4_xattr_set+0x230/0x320 fs/ext4/xattr.c:2549
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x274/0x600 fs/xattr.c:665
 path_setxattrat+0x364/0x3a0 fs/xattr.c:713
 __do_sys_setxattr fs/xattr.c:747 [inline]
 __se_sys_setxattr fs/xattr.c:743 [inline]
 __x64_sys_setxattr+0xbc/0xe0 fs/xattr.c:743
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f049bd8e969
RSP: 002b:00007f049cb91038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f049bfb6080 RCX: 00007f049bd8e969
RDX: 0000200000001400 RSI: 00002000000001c0 RDI: 0000200000000380
RBP: 00007f049be10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000835 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f049bfb6080 R15: 00007ffd30a7dc78
 </TASK>
INFO: task syz.0.301:7444 blocked for more than 145 seconds.
      Not tainted 6.15.0-rc5-syzkaller-00038-g707df3375124 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.301       state:D stack:26424 pid:7444  tgid:7426  ppid:5822   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6860
 mb_cache_entry_wait_unused+0x165/0x250 fs/mbcache.c:148
 ext4_evict_ea_inode+0x14d/0x2f0 fs/ext4/xattr.c:477
 ext4_evict_inode+0x16f/0xed0 fs/ext4/inode.c:188
 evict+0x504/0x9c0 fs/inode.c:810
 ext4_xattr_set_entry+0x12dc/0x1e20 fs/ext4/xattr.c:1839
 ext4_xattr_block_set+0x61b/0x2ac0 fs/ext4/xattr.c:1951
 ext4_xattr_set_handle+0xdd7/0x1590 fs/ext4/xattr.c:2438
 ext4_xattr_set+0x230/0x320 fs/ext4/xattr.c:2549
 __vfs_setxattr+0x43c/0x480 fs/xattr.c:200
 __vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
 vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
 do_setxattr fs/xattr.c:636 [inline]
 filename_setxattr+0x274/0x600 fs/xattr.c:665
 path_setxattrat+0x364/0x3a0 fs/xattr.c:713
 __do_sys_setxattr fs/xattr.c:747 [inline]
 __se_sys_setxattr fs/xattr.c:743 [inline]
 __x64_sys_setxattr+0xbc/0xe0 fs/xattr.c:743
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f049bd8e969
RSP: 002b:00007f049cb70038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f049bfb6160 RCX: 00007f049bd8e969
RDX: 0000200000000000 RSI: 0000200000000080 RDI: 0000200000000180
RBP: 00007f049be10ab1 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000835 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f049bfb6160 R15: 00007ffd30a7dc78
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
 #0: ffffffff8df41338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #0: ffffffff8df41338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b7/0x730 kernel/rcu/tree_exp.h:998
2 locks held by kworker/u8:0/12:
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b1/0x17a0 kernel/workqueue.c:3319
 #1: ffffc90000117c60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000117c60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ec/0x17a0 kernel/workqueue.c:3319
3 locks held by kworker/u8:1/13:
1 lock held by khungtaskd/31:
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6764
2 locks held by kworker/u8:5/138:
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b1/0x17a0 kernel/workqueue.c:3319
 #1: ffffc90002e3fc60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90002e3fc60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ec/0x17a0 kernel/workqueue.c:3319
2 locks held by kworker/u8:6/3491:
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b1/0x17a0 kernel/workqueue.c:3319
 #1: ffffc9000c52fc60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000c52fc60 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ec/0x17a0 kernel/workqueue.c:3319
2 locks held by kworker/u8:7/3516:
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b1/0x17a0 kernel/workqueue.c:3319
 #1: ffff8880b8823b08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x39e/0x6d0 kernel/sched/psi.c:987
2 locks held by getty/5581:
 #0: ffff8880305530a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900030062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/5841:
 #0: ffff8880b8839b58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:613
3 locks held by syz.0.301/7443:
 #0: ffff8880245c0420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:556
 #1: ffff88807cf9a1f0 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff88807cf9a1f0 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: vfs_setxattr+0x144/0x2f0 fs/xattr.c:320
 #2: ffff88807cf99e80 (&ei->xattr_sem){++++}-{4:4}, at: ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline]
 #2: ffff88807cf99e80 (&ei->xattr_sem){++++}-{4:4}, at: ext4_xattr_set_handle+0x165/0x1590 fs/ext4/xattr.c:2362
3 locks held by syz.0.301/7444:
 #0: ffff8880245c0420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:556
 #1: ffff888033cf0438 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #1: ffff888033cf0438 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: vfs_setxattr+0x144/0x2f0 fs/xattr.c:320
 #2: ffff888033cf00c8 (&ei->xattr_sem){++++}-{4:4}, at: ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline]
 #2: ffff888033cf00c8 (&ei->xattr_sem){++++}-{4:4}, at: ext4_xattr_set_handle+0x165/0x1590 fs/ext4/xattr.c:2362
2 locks held by syz.1.643/8950:
 #0: ffff8880578f1408 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #0: ffff8880578f1408 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: __sock_release net/socket.c:646 [inline]
 #0: ffff8880578f1408 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240 net/socket.c:1391
 #1: ffffffff8df41338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #1: ffffffff8df41338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b7/0x730 kernel/rcu/tree_exp.h:998
1 lock held by syz.5.645/8946:
 #0: ffff8880578f0808 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #0: ffff8880578f0808 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: __sock_release net/socket.c:646 [inline]
 #0: ffff8880578f0808 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240 net/socket.c:1391

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc5-syzkaller-00038-g707df3375124 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:437
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6875 Comm: syz-executor Not tainted 6.15.0-rc5-syzkaller-00038-g707df3375124 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
RIP: 0010:io_serial_out+0x7c/0xc0 drivers/tty/serial/8250/8250_port.c:416
Code: 1b 82 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 fc 0f e4 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d e9 12 8c d2 fb cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc9000475f530 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: ffff8880240f8237 R09: 1ffff1100481f046
R10: dffffc0000000000 R11: ffffffff853db470 R12: dffffc0000000000
R13: ffffffff99847c42 R14: ffffffff99b4cbc0 R15: 0000000000000000
FS:  0000555591110500(0000) GS:ffff8881260cb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdb5d6d9fc CR3: 00000000743fa000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 serial_port_out include/linux/serial_core.h:796 [inline]
 serial8250_console_putchar drivers/tty/serial/8250/8250_port.c:3306 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:-1 [inline]
 serial8250_console_write+0x1410/0x1ba0 drivers/tty/serial/8250/8250_port.c:3456
 console_emit_next_record kernel/printk/printk.c:3138 [inline]
 console_flush_all+0x728/0xc40 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xc4/0x270 kernel/printk/printk.c:3325
 vprintk_emit+0x5b7/0x7a0 kernel/printk/printk.c:2450
 _printk+0xcf/0x120 kernel/printk/printk.c:2475
 __ext4_msg+0x293/0x2a0 fs/ext4/super.c:985
 ext4_put_super+0xb8/0xc40 fs/ext4/super.c:1290
 generic_shutdown_super+0x135/0x2c0 fs/super.c:642
 kill_block_super+0x44/0x90 fs/super.c:1710
 ext4_kill_sb+0x68/0xb0 fs/ext4/super.c:7393
 deactivate_locked_super+0xbc/0x130 fs/super.c:473
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1435
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work+0x5e/0x80 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x9a/0x120 kernel/entry/common.c:218
 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f497e78fc97
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd64c936a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f497e81089d RCX: 00007f497e78fc97
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd64c93760
RBP: 00007ffd64c93760 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd64c947f0
R13: 00007f497e81089d R14: 0000000000061267 R15: 00007ffd64c94830
 </TASK>

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/07 22:16 upstream 707df3375124 350f4ffc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2025/03/24 11:57 upstream 586de92313fc 875573af .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2025/02/27 00:06 upstream 5394eea10651 6a8fcbc4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2025/01/12 18:52 upstream b62cef9a5c67 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2024/12/31 14:05 upstream ccb98ccef0e5 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2024/12/17 14:00 upstream f44d154d6e3d f93b2b55 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2024/12/16 01:55 upstream dccbe2047a5b 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in find_inode_fast
2024/12/19 01:10 linux-next 7fa366f1b6e3 1432fc84 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root INFO: task hung in find_inode_fast
2025/03/09 22:13 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 77c95b8c7a16 163f510d .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-upstream-gce-arm64 INFO: task hung in find_inode_fast
* Struck through repros no longer work on HEAD.