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From: syzbot syzbot+7b8f7100327c574c016f@syzkaller.appspotmail.com Subject: INFO: task hung in remove_proc_subtree To: adobriyan@gmail.com, akpm@linux-foundation.org, ebiederm@xmission.com, gladkov.alexey@gmail.com, keescook@chromium.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Date: Wed, 16 Dec 2020 09:54:09 -0800

Hello,

syzbot found the following issue on:

HEAD commit: 7f376f19 Merge tag 'mtd/fixes-for-5.10-rc8' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=102ac937500000 kernel config: https://syzkaller.appspot.com/x/.config?x=3416bb960d5c705d dashboard link: https://syzkaller.appspot.com/bug?extid=7b8f7100327c574c016f compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=166e240f500000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=147eddef500000

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7b8f7100327c574c016f@syzkaller.appspotmail.com

INFO: task kworker/1:2:8489 blocked for more than 143 seconds. Not tainted 5.10.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:2 state:D stack:24264 pid: 8489 ppid: 2 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:3779 [inline] __schedule+0x893/0x2130 kernel/sched/core.c:4528 schedule+0xcf/0x270 kernel/sched/core.c:4606 schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1847 do_wait_for_common kernel/sched/completion.c:85 [inline] __wait_for_common kernel/sched/completion.c:106 [inline] wait_for_common kernel/sched/completion.c:117 [inline] wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 proc_entry_rundown+0x1a1/0x1d0 fs/proc/inode.c:262 remove_proc_subtree+0x26f/0x520 fs/proc/generic.c:752 proc_remove fs/proc/generic.c:775 [inline] proc_remove+0x66/0x90 fs/proc/generic.c:772 snd_info_disconnect+0x946/0xc20 sound/core/info.c:757 snd_info_disconnect sound/core/info.c:756 [inline] snd_info_card_disconnect+0x134/0x230 sound/core/info.c:577 snd_card_disconnect+0x2be/0x510 sound/core/init.c:421 usb_audio_disconnect+0x2c4/0x7f0 sound/usb/card.c:877 usb_unbind_interface+0x1d8/0x8d0 drivers/usb/core/driver.c:458 __device_release_driver+0x3bd/0x6f0 drivers/base/dd.c:1154 device_release_driver_internal drivers/base/dd.c:1185 [inline] device_release_driver+0x26/0x40 drivers/base/dd.c:1208 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:533 device_del+0x502/0xec0 drivers/base/core.c:3115 usb_disable_device+0x35b/0x7b0 drivers/usb/core/message.c:1410 usb_disconnect.cold+0x27d/0x780 drivers/usb/core/hub.c:2217 hub_port_connect drivers/usb/core/hub.c:5073 [inline] hub_port_connect_change drivers/usb/core/hub.c:5362 [inline] port_event drivers/usb/core/hub.c:5508 [inline] hub_event+0x1c8a/0x42d0 drivers/usb/core/hub.c:5590 process_one_work+0x933/0x15a0 kernel/workqueue.c:2272 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 INFO: task syz-executor488:14592 blocked for more than 143 seconds. Not tainted 5.10.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor488 state:D stack:28144 pid:14592 ppid: 8497 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:3779 [inline] __schedule+0x893/0x2130 kernel/sched/core.c:4528 schedule+0xcf/0x270 kernel/sched/core.c:4606 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4665 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x3e2/0x10e0 kernel/locking/mutex.c:1103 snd_info_text_entry_open+0x80/0x2e0 sound/core/info.c:373 proc_reg_open+0x25d/0x620 fs/proc/inode.c:538 do_dentry_open+0x4b9/0x11b0 fs/open.c:817 do_open fs/namei.c:3252 [inline] path_openat+0x1b9a/0x2730 fs/namei.c:3369 do_filp_open+0x17e/0x3c0 fs/namei.c:3396 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x450739 RSP: 002b:00007f4a57aefce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000700028 RCX: 0000000000450739 RDX: 0000000000000001 RSI: 00000000200001c0 RDI: ffffffffffffff9c RBP: 0000000000700020 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000070002c R13: 000000000080fbcf R14: 00007f4a57af09c0 R15: 0000000000000000

Showing all locks held in the system: 1 lock held by khungtaskd/1654: #0: ffffffff8b3378e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6254 1 lock held by in:imklog/8177: #0: ffff888012ef1270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:932 7 locks held by kworker/1:2/8489: #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888014c3fd38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x821/0x15a0 kernel/workqueue.c:2243 #1: ffffc90000e9fda8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2247 #2: ffff88801c28a218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:731 [inline] #2: ffff88801c28a218 (&dev->mutex){....}-{3:3}, at: hub_event+0x1c5/0x42d0 drivers/usb/core/hub.c:5536 #3: ffff888022bc8218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:731 [inline] #3: ffff888022bc8218 (&dev->mutex){....}-{3:3}, at: usb_disconnect.cold+0x43/0x780 drivers/usb/core/hub.c:2208 #4: ffff888018ea21a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:731 [inline] #4: ffff888018ea21a8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:975 [inline] #4: ffff888018ea21a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal drivers/base/dd.c:1182 [inline] #4: ffff888018ea21a8 (&dev->mutex){....}-{3:3}, at: device_release_driver+0x1c/0x40 drivers/base/dd.c:1208 #5: ffffffff8c8ae5e8 (register_mutex#6){+.+.}-{3:3}, at: usb_audio_disconnect+0xe4/0x7f0 sound/usb/card.c:866 #6: ffffffff8c838028 (info_mutex){+.+.}-{3:3}, at: snd_info_card_disconnect+0x33/0x230 sound/core/info.c:573 1 lock held by syz-executor488/14592: #0: ffffffff8c838028 (info_mutex){+.+.}-{3:3}, at: snd_info_text_entry_open+0x80/0x2e0 sound/core/info.c:373

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

NMI backtrace for cpu 1 CPU: 1 PID: 1654 Comm: khungtaskd Not tainted 5.10.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0xd43/0xfa0 kernel/hung_task.c:294 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: kworker/u4:2 Not tainted 5.10.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: phy3 ieee80211_iface_work RIP: 0010:__lock_acquire+0x372/0x5500 kernel/locking/lockdep.c:4770 Code: ed 44 09 e8 41 81 e7 00 00 03 00 41 c1 e1 13 41 09 c7 89 d8 48 c1 ea 03 c1 e0 12 25 00 00 04 00 41 09 c7 8b 84 24 38 01 00 00 <45> 09 f9 c1 e0 14 41 09 c1 41 8b 44 24 20 25 ff 1f 00 00 41 09 c1 RSP: 0018:ffffc90000e1f890 EFLAGS: 00000006 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 1ffff110021e47c6 RSI: 0000000000000004 RDI: ffff888010f23e34 RBP: ffff888010f23480 R08: 0000000000000001 R09: 0000000000080000 R10: 0000000000000078 R11: 0000000000000000 R12: ffff888010f23e10 R13: 0000000000000000 R14: ffffffff8b3378e0 R15: 0000000000020000 FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa2708ab000 CR3: 0000000025718000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402 rcu_lock_acquire include/linux/rcupdate.h:248 [inline] rcu_read_lock include/linux/rcupdate.h:641 [inline] cgroup_account_cputime include/linux/cgroup.h:781 [inline] update_curr+0x311/0x840 kernel/sched/fair.c:870 enqueue_entity+0x435/0x2080 kernel/sched/fair.c:4206 enqueue_task_fair+0x1d8/0x1a70 kernel/sched/fair.c:5502 enqueue_task kernel/sched/core.c:1572 [inline] activate_task kernel/sched/core.c:1591 [inline] ttwu_do_activate+0x17f/0x660 kernel/sched/core.c:2511 ttwu_queue kernel/sched/core.c:2701 [inline] try_to_wake_up+0x54c/0x1330 kernel/sched/core.c:2979 wake_up_worker kernel/workqueue.c:837 [inline] process_one_work+0x75a/0x15a0 kernel/workqueue.c:2235 worker_thread+0x64c/0x1120 kernel/workqueue.c:2418 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

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