syzbot


INFO: task hung in walk_component (5)

Status: upstream: reported C repro on 2022/08/22 12:38
Reported-by: syzbot+8fba0e0286621ce71edd@syzkaller.appspotmail.com
First crash: 110d, last: 13d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: INFO: task hung in walk_component (log)
Repro: C syz .config
similar bugs (8):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in walk_component 1 633d 633d 0/1 auto-closed as invalid on 2021/07/04 02:47
upstream INFO: task hung in walk_component (3) 9 352d 523d 0/24 closed as invalid on 2022/02/07 19:19
linux-4.19 INFO: task hung in walk_component (2) 2 422d 476d 0/1 auto-closed as invalid on 2022/01/31 04:51
upstream INFO: task hung in walk_component (2) 31 626d 627d 22/24 fixed on 2021/04/09 19:46
upstream INFO: task hung in walk_component (4) 4 263d 286d 0/24 auto-closed as invalid on 2022/06/09 10:18
android-44 INFO: task hung in walk_component 1 1310d 1310d 0/2 auto-closed as invalid on 2019/10/25 08:50
linux-4.19 INFO: task hung in walk_component (3) C error 3 12d 118d 0/1 upstream: reported C repro on 2022/08/03 09:11
upstream INFO: task hung in walk_component 1 1599d 1599d 0/24 closed as invalid on 2018/09/05 12:51

Sample crash report:
INFO: task syslogd:2955 blocked for more than 143 seconds.
      Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syslogd         state:D stack:25472 pid:2955  ppid:1      flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5191 [inline]
 __schedule+0xae9/0x53f0 kernel/sched/core.c:6503
 schedule+0xda/0x1b0 kernel/sched/core.c:6579
 rwsem_down_read_slowpath+0x59f/0xb10 kernel/locking/rwsem.c:1095
 __down_read_common kernel/locking/rwsem.c:1260 [inline]
 __down_read kernel/locking/rwsem.c:1269 [inline]
 down_read+0xe2/0x450 kernel/locking/rwsem.c:1511
 inode_lock_shared include/linux/fs.h:766 [inline]
 lookup_slow fs/namei.c:1701 [inline]
 walk_component+0x332/0x5a0 fs/namei.c:1993
 link_path_walk.part.0+0x74e/0xe20 fs/namei.c:2320
 link_path_walk fs/namei.c:2245 [inline]
 path_openat+0x262/0x2860 fs/namei.c:3709
 do_filp_open+0x1b6/0x400 fs/namei.c:3740
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcf5897e697
RSP: 002b:00007ffea18da1f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055c65c0fe910 RCX: 00007fcf5897e697
RDX: 0000000000000d41 RSI: 00007fcf58b0c99a RDI: 00000000ffffff9c
RBP: 00007fcf58b0c99a R08: 00007fcf58a0e040 R09: 00007fcf58a0e0c0
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000d41
R13: 000055c65c0fea50 R14: 0000000000000003 R15: 000055c65c0fea60
 </TASK>
INFO: task syz-executor123:3606 blocked for more than 143 seconds.
      Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor123 state:D stack:27368 pid:3606  ppid:3603   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5191 [inline]
 __schedule+0xae9/0x53f0 kernel/sched/core.c:6503
 schedule+0xda/0x1b0 kernel/sched/core.c:6579
 rwsem_down_read_slowpath+0x59f/0xb10 kernel/locking/rwsem.c:1095
 __down_read_common kernel/locking/rwsem.c:1260 [inline]
 __down_read kernel/locking/rwsem.c:1269 [inline]
 down_read+0xe2/0x450 kernel/locking/rwsem.c:1511
 inode_lock_shared include/linux/fs.h:766 [inline]
 lookup_slow fs/namei.c:1701 [inline]
 walk_component+0x332/0x5a0 fs/namei.c:1993
 link_path_walk.part.0+0x74e/0xe20 fs/namei.c:2320
 link_path_walk fs/namei.c:2245 [inline]
 path_openat+0x262/0x2860 fs/namei.c:3709
 do_filp_open+0x1b6/0x400 fs/namei.c:3740
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6453d38338
RSP: 002b:00007ffdcd4b6a80 EFLAGS: 00000287 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ffdcd4b6af0 RCX: 00007f6453d38338
RDX: 0000000000090800 RSI: 00007f6453d8a004 RDI: 00000000ffffff9c
RBP: 0000000000000e17 R08: 0000000000090800 R09: 00007f6453d8a004
R10: 0000000000000000 R11: 0000000000000287 R12: 00007ffdcd4b6c74
R13: 00007ffdcd4b6c74 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
INFO: task syz-executor123:3608 blocked for more than 143 seconds.
      Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor123 state:D stack:26520 pid:3608  ppid:3606   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5191 [inline]
 __schedule+0xae9/0x53f0 kernel/sched/core.c:6503
 schedule+0xda/0x1b0 kernel/sched/core.c:6579
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6638
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0xa44/0x1350 kernel/locking/mutex.c:747
 fuse_lock_inode+0xce/0x100 fs/fuse/inode.c:468
 fuse_lookup.part.0+0x86/0x390 fs/fuse/dir.c:432
 fuse_lookup+0x70/0x90 fs/fuse/dir.c:429
 __lookup_slow+0x24c/0x460 fs/namei.c:1685
 lookup_slow fs/namei.c:1702 [inline]
 walk_component+0x33f/0x5a0 fs/namei.c:1993
 link_path_walk.part.0+0x74e/0xe20 fs/namei.c:2320
 link_path_walk fs/namei.c:2245 [inline]
 path_openat+0x262/0x2860 fs/namei.c:3709
 do_filp_open+0x1b6/0x400 fs/namei.c:3740
 do_sys_openat2+0x16d/0x4c0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6453cf4f34
RSP: 002b:00007f6453ce4e60 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f6453cf4f34
RDX: 0000000000004000 RSI: 00007f6453ce4ee0 RDI: 00000000ffffff9c
RBP: 00007f6453ce4ee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000004000
R13: 0000000000000065 R14: 00007f6453d8c0a8 R15: 00007f6453dbf4c8
 </TASK>
INFO: task syz-executor123:3610 blocked for more than 144 seconds.
      Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor123 state:D stack:28352 pid:3610  ppid:3606   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5191 [inline]
 __schedule+0xae9/0x53f0 kernel/sched/core.c:6503
 schedule+0xda/0x1b0 kernel/sched/core.c:6579
 rwsem_down_write_slowpath+0x5fc/0x12d0 kernel/locking/rwsem.c:1190
 __down_write_common kernel/locking/rwsem.c:1305 [inline]
 __down_write_common kernel/locking/rwsem.c:1302 [inline]
 __down_write kernel/locking/rwsem.c:1314 [inline]
 down_write_nested+0x1e8/0x220 kernel/locking/rwsem.c:1673
 inode_lock_nested include/linux/fs.h:791 [inline]
 fuse_reverse_inval_entry+0x51/0x550 fs/fuse/dir.c:1184
 fuse_notify_delete fs/fuse/dev.c:1549 [inline]
 fuse_notify fs/fuse/dev.c:1798 [inline]
 fuse_dev_do_write+0x1aab/0x2c00 fs/fuse/dev.c:1873
 fuse_dev_write+0x150/0x1e0 fs/fuse/dev.c:1957
 call_write_iter include/linux/fs.h:2191 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x9e9/0xdd0 fs/read_write.c:584
 ksys_write+0x127/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6453d38669
RSP: 002b:00007f6453cc42f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6453dbf4d0 RCX: 00007f6453d38669
RDX: 000000000000002c RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007f6453d8c084 R08: 0000000000000000 R09: 0000000000000000
R10: 00007f6453cc4700 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 0000000000000003 R14: 00007f6453d8c0a8 R15: 00007f6453dbf4d8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8bf87e30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x26/0xc70 kernel/rcu/tasks.h:507
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8bf87b30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x26/0xc70 kernel/rcu/tasks.h:507
1 lock held by khungtaskd/27:
 #0: ffffffff8bf88980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6494
2 locks held by kworker/u4:2/33:
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:636 [inline]
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:663 [inline]
 #0: ffff888011869138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x86d/0x1710 kernel/workqueue.c:2260
 #1: ffffc90000aa7da8 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1710 kernel/workqueue.c:2264
1 lock held by syslogd/2955:
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
2 locks held by udevd/2973:
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
 #1: ffff8880727a85b8 (&fi->mutex){+.+.}-{3:3}, at: fuse_lock_inode+0xce/0x100 fs/fuse/inode.c:468
2 locks held by getty/3283:
 #0: ffff88814ab27098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffffc900031262f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef0/0x13e0 drivers/tty/n_tty.c:2177
1 lock held by syz-executor123/3606:
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
2 locks held by syz-executor123/3608:
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
 #0: ffff8880727a8150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
 #1: ffff8880727a85b8 (&fi->mutex){+.+.}-{3:3}, at: fuse_lock_inode+0xce/0x100 fs/fuse/inode.c:468
2 locks held by syz-executor123/3610:
 #0: ffff888079e36338 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify_delete fs/fuse/dev.c:1548 [inline]
 #0: ffff888079e36338 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify fs/fuse/dev.c:1798 [inline]
 #0: ffff888079e36338 (&fc->killsb){.+.+}-{3:3}, at: fuse_dev_do_write+0x2567/0x2c00 fs/fuse/dev.c:1873
 #1: ffff8880727a8150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
 #1: ffff8880727a8150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: fuse_reverse_inval_entry+0x51/0x550 fs/fuse/dir.c:1184

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x24/0x18a lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x32f/0x3c0 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+0xc71/0xfc0 kernel/hung_task.c:377
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x1fd/0x2a0 drivers/acpi/processor_idle.c:572

Crashes (11):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2022/11/15 20:32 upstream e01d50cbd6ee 97de9cfc .config log report syz C INFO: task hung in walk_component
ci-upstream-kasan-gce-root 2022/08/18 12:21 upstream 274a2eebf80c d58e263f .config log report syz C INFO: task hung in walk_component
ci-upstream-linux-next-kasan-gce-root 2022/10/02 09:12 linux-next aaa11ce2ffc8 feb56351 .config log report syz C INFO: task hung in walk_component
ci-upstream-kasan-gce-selinux-root 2022/10/10 03:16 upstream a6afa4199d3d aea5da89 .config log report info INFO: task hung in walk_component
ci-upstream-kasan-gce-selinux-root 2022/09/30 05:15 upstream 511cce163b75 1d385642 .config log report info INFO: task hung in walk_component
ci-upstream-kasan-gce-root 2022/09/16 03:39 upstream 3245cb65fd91 dd9a85ff .config log report info INFO: task hung in walk_component
ci-upstream-kasan-gce-root 2022/08/21 00:15 upstream 50cd95ac4654 26a13b38 .config log report info INFO: task hung in walk_component
ci-upstream-kasan-gce-root 2022/08/11 01:20 upstream 200e340f2196 a6201f11 .config log report info INFO: task hung in walk_component
ci-upstream-kasan-gce-root 2022/08/11 00:51 upstream 200e340f2196 a6201f11 .config log report info INFO: task hung in walk_component
ci-upstream-linux-next-kasan-gce-root 2022/10/18 04:52 linux-next 77d8bf70fac0 754863b4 .config log report info INFO: task hung in walk_component
ci-upstream-linux-next-kasan-gce-root 2022/09/24 11:23 linux-next aaa11ce2ffc8 0042f2b4 .config log report info INFO: task hung in walk_component
* Struck through repros no longer work on HEAD.