[syzbot] INFO: task hung in walk_component (5)

syzbot
2022-08-22T12:38:37Z

Hello,

syzbot found the following issue on:

HEAD commit: 274a2eebf80c Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=110b183d080000
kernel config: https://syzkaller.appspot.com/x/.config?x=3b9175e0879a7749
dashboard link: https://syzkaller.appspot.com/bug?extid=8fba0e0286621ce71edd
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13db992d080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1301c1f3080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fba0e0286621ce71edd@syzkaller.appspotmail.com

INFO: task syslogd:2954 blocked for more than 143 seconds.
Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syslogd state:D stack:25896 pid: 2954 ppid: 1 flags:0x00000000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5182 [inline]
__schedule+0xadf/0x52b0 kernel/sched/core.c:6494
schedule+0xda/0x1b0 kernel/sched/core.c:6570
rwsem_down_read_slowpath+0x59f/0xb10 kernel/locking/rwsem.c:1087
__down_read_common kernel/locking/rwsem.c:1252 [inline]
__down_read kernel/locking/rwsem.c:1261 [inline]
down_read+0xe2/0x450 kernel/locking/rwsem.c:1501
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+0x262/0x28f0 fs/namei.c:3687
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1311
do_sys_open fs/open.c:1327 [inline]
__do_sys_openat fs/open.c:1343 [inline]
__se_sys_openat fs/open.c:1338 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1338
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: 0033:0x7f600686b697
RSP: 002b:00007ffc893ed6a0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055f27b512910 RCX: 00007f600686b697
RDX: 0000000000000d41 RSI: 00007f60069f999a RDI: 00000000ffffff9c
RBP: 00007f60069f999a R08: 00007f60068fb040 R09: 00007f60068fb0c0
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000d41
R13: 000055f27b512a50 R14: 0000000000000003 R15: 000055f27b512a60
</TASK>
INFO: task udevd:2972 blocked for more than 143 seconds.
Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd state:D stack:27096 pid: 2972 ppid: 1 flags:0x00000000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5182 [inline]
__schedule+0xadf/0x52b0 kernel/sched/core.c:6494
schedule+0xda/0x1b0 kernel/sched/core.c:6570
rwsem_down_read_slowpath+0x59f/0xb10 kernel/locking/rwsem.c:1087
__down_read_common kernel/locking/rwsem.c:1252 [inline]
__down_read kernel/locking/rwsem.c:1261 [inline]
down_read+0xe2/0x450 kernel/locking/rwsem.c:1501
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:2244 [inline]
path_lookupat+0xb7/0x840 fs/namei.c:2473
filename_lookup+0x1ce/0x590 fs/namei.c:2503
vfs_statx+0x148/0x390 fs/stat.c:228
vfs_fstatat+0x8c/0xb0 fs/stat.c:255
__do_sys_newfstatat+0x91/0x110 fs/stat.c:425
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: 0033:0x7f93c7f7a1da
RSP: 002b:00007fffc0378198 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 0000555918b966a0 RCX: 00007f93c7f7a1da
RDX: 00007fffc03781a8 RSI: 0000555918b847ed RDI: 00000000ffffff9c
RBP: 0000555918e507b8 R08: 0000000002a8adc5 R09: 00007fffc03c7080
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000000 R15: 00007fffc03781a8
</TASK>
INFO: task syz-executor412:3612 blocked for more than 143 seconds.
Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor412 state:D stack:26448 pid: 3612 ppid: 3609 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5182 [inline]
__schedule+0xadf/0x52b0 kernel/sched/core.c:6494
schedule+0xda/0x1b0 kernel/sched/core.c:6570
rwsem_down_read_slowpath+0x59f/0xb10 kernel/locking/rwsem.c:1087
__down_read_common kernel/locking/rwsem.c:1252 [inline]
__down_read kernel/locking/rwsem.c:1261 [inline]
down_read+0xe2/0x450 kernel/locking/rwsem.c:1501
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+0x262/0x28f0 fs/namei.c:3687
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1311
do_sys_open fs/open.c:1327 [inline]
__do_sys_openat fs/open.c:1343 [inline]
__se_sys_openat fs/open.c:1338 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1338
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: 0033:0x7f29b1af0238
RSP: 002b:00007ffea611c300 EFLAGS: 00000287 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f29b1af0238
RDX: 0000000000090800 RSI: 00007f29b1b46060 RDI: 00000000ffffff9c
RBP: 0000000000000e1d R08: 0000000000090800 R09: 00007f29b1b46060
R10: 0000000000000000 R11: 0000000000000287 R12: 00007ffea611c394
R13: 00007ffea611c3f0 R14: 0000000000000000 R15: 431bde82d7b634db
</TASK>
INFO: task syz-executor412:3614 blocked for more than 144 seconds.
Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor412 state:D stack:26960 pid: 3614 ppid: 3612 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5182 [inline]
__schedule+0xadf/0x52b0 kernel/sched/core.c:6494
schedule+0xda/0x1b0 kernel/sched/core.c:6570
request_wait_answer+0x46d/0x850 fs/fuse/dev.c:407
__fuse_request_send fs/fuse/dev.c:426 [inline]
fuse_simple_request+0x71d/0xe50 fs/fuse/dev.c:511
fuse_lookup_name+0x280/0x630 fs/fuse/dir.c:392
fuse_lookup.part.0+0xdf/0x390 fs/fuse/dir.c:433
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+0x262/0x28f0 fs/namei.c:3687
do_filp_open+0x1b6/0x400 fs/namei.c:3718
do_sys_openat2+0x16d/0x4c0 fs/open.c:1311
do_sys_open fs/open.c:1327 [inline]
__do_sys_openat fs/open.c:1343 [inline]
__se_sys_openat fs/open.c:1338 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1338
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: 0033:0x7f29b1af05b9
RSP: 002b:00007f29b1aa12f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f29b1b7b4c0 RCX: 00007f29b1af05b9
RDX: 0000000000000042 RSI: 0000000020002080 RDI: ffffffffffffff9c
RBP: 00007f29b1b48084 R08: 0000000000000065 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000065
R13: 00007f29b1b480a8 R14: 31f4000000000002 R15: 00007f29b1b7b4c8
</TASK>
INFO: task syz-executor412:3616 blocked for more than 144 seconds.
Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor412 state:D stack:28392 pid: 3616 ppid: 3612 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5182 [inline]
__schedule+0xadf/0x52b0 kernel/sched/core.c:6494
schedule+0xda/0x1b0 kernel/sched/core.c:6570
rwsem_down_write_slowpath+0x59c/0x11e0 kernel/locking/rwsem.c:1182
__down_write_common kernel/locking/rwsem.c:1297 [inline]
__down_write_common kernel/locking/rwsem.c:1294 [inline]
__down_write kernel/locking/rwsem.c:1306 [inline]
down_write_nested+0x139/0x150 kernel/locking/rwsem.c:1663
inode_lock_nested include/linux/fs.h:791 [inline]
fuse_reverse_inval_entry+0x51/0x540 fs/fuse/dir.c:1167
fuse_notify_delete fs/fuse/dev.c:1548 [inline]
fuse_notify fs/fuse/dev.c:1797 [inline]
fuse_dev_do_write+0x1aab/0x2c00 fs/fuse/dev.c:1872
fuse_dev_write+0x150/0x1e0 fs/fuse/dev.c:1956
call_write_iter include/linux/fs.h:2187 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:578
ksys_write+0x127/0x250 fs/read_write.c:631
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: 0033:0x7f29b1af05b9
RSP: 002b:00007f29b1a802f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f29b1b7b4d0 RCX: 00007f29b1af05b9
RDX: 000000000000002c RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007f29b1b48084 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f29b1b480a8 R14: 31f4000000000002 R15: 00007f29b1b7b4d8
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8bf88770 (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: ffffffff8bf88470 (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/28:
#0: ffffffff8bf892c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6492
2 locks held by kworker/u4:4/57:
#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+0x87a/0x1610 kernel/workqueue.c:2260
#1: ffffc90001587da8 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264
1 lock held by syslogd/2954:
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
1 lock held by udevd/2972:
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
2 locks held by getty/3286:
#0: ffff88814adb2098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
#1: ffffc90002d162f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef0/0x13e0 drivers/tty/n_tty.c:2177
1 lock held by syz-executor412/3612:
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
2 locks held by syz-executor412/3614:
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:766 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: lookup_slow fs/namei.c:1701 [inline]
#0: ffff88806f868150 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1993
#1: ffff88806f8685b8 (&fi->mutex){+.+.}-{3:3}, at: fuse_lock_inode+0xce/0x100 fs/fuse/inode.c:468
2 locks held by syz-executor412/3616:
#0: ffff88814ab26b38 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify_delete fs/fuse/dev.c:1547 [inline]
#0: ffff88814ab26b38 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify fs/fuse/dev.c:1797 [inline]
#0: ffff88814ab26b38 (&fc->killsb){.+.+}-{3:3}, at: fuse_dev_do_write+0x2567/0x2c00 fs/fuse/dev.c:1872
#1: ffff88806f868150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff88806f868150 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: fuse_reverse_inval_entry+0x51/0x540 fs/fuse/dir.c:1167

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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+0x46/0x14f lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x206/0x250 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xc18/0xf50 kernel/hung_task.c:369
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
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc1-syzkaller-00025-g274a2eebf80c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:__sanitizer_cov_trace_cmp8+0x4/0x20 kernel/kcov.c:276
Code: 00 00 00 00 00 90 48 8b 0c 24 89 f2 89 fe bf 04 00 00 00 e9 1e ff ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 0c 24 <48> 89 f2 48 89 fe bf 06 00 00 00 e9 fc fe ff ff 66 66 2e 0f 1f 84
RSP: 0018:ffffc90000177da0 EFLAGS: 00000046
RAX: 00000042efb73b7f RBX: ffff8880b9b2ae60 RCX: ffffffff816ff959
RDX: 1ffff110173655cf RSI: 00000042efb73b7f RDI: 00000042efb73b7f
RBP: 0000000000000001 R08: 0000000000000007 R09: 7fffffffffffffff
R10: 00000042efb73b7f R11: 0000000000000000 R12: 00000042efb73b7f
R13: 00000042efb73b7f R14: 0000000000000001 R15: 00000042efb73b7f
FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe71c5af990 CR3: 000000000bc8e000 CR4: 0000000000350ee0
Call Trace:
<TASK>
tick_nohz_stop_tick kernel/time/tick-sched.c:896 [inline]
__tick_nohz_idle_stop_tick kernel/time/tick-sched.c:1108 [inline]
tick_nohz_idle_stop_tick+0x699/0xbf0 kernel/time/tick-sched.c:1129
cpuidle_idle_call kernel/sched/idle.c:232 [inline]
do_idle+0x37b/0x590 kernel/sched/idle.c:303
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400
start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:262
secondary_startup_64_no_verify+0xce/0xdb
</TASK>

---
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