INFO: task hung in nbd

INFO: task hung in nbd_ioctl (3)
Status: upstream: reported C repro on 2020/09/28 07:17
Reported-by: syzbot+fe03c50d25c0188f7487@syzkaller.appspotmail.com
First crash: 304d, last: 6d00h

Cause bisection: introduced by (bisect log) :
commit e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Author: Mike Christie <mchristi@redhat.com>
Date: Sun Aug 4 19:10:06 2019 +0000

nbd: fix max number of supported devs

Crash: INFO: task hung in nbd_ioctl (log)
Repro: syz .config

Fix bisection: fixed by (bisect log) [merge commit]:
commit da0628559871475b482f015dc24c9bef372936e4
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon Dec 14 20:05:10 2020 +0000

Merge tag 'tomoyo-pr-20201214' of git://git.osdn.net/gitroot/tomoyo/tomoyo-test1

similar bugs (7):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
linux-4.14	INFO: task hung in nbd_ioctl	C		done	18	580d	654d	1/1	fixed on 2019/12/28 10:32
linux-4.14	INFO: task hung in nbd_ioctl (2)	C		done	16	327d	572d	1/1	fixed on 2020/10/21 11:01
upstream	INFO: task hung in nbd_ioctl (2)				37	334d	387d	17/22	fixed on 2020/09/25 01:17
upstream	INFO: task hung in nbd_ioctl	C	done		71	632d	667d	14/22	fixed on 2019/11/06 12:39
linux-4.19	INFO: task hung in nbd_ioctl	C			52	22d	655d	0/1	upstream: reported C repro on 2019/10/12 13:11
linux-4.14	INFO: task hung in nbd_ioctl (3)	C			7	14d	258d	0/1	upstream: reported C repro on 2020/11/13 07:37
upstream	INFO: task can't die in nbd_ioctl	C	done		3	107d	297d	0/22	upstream: reported C repro on 2020/10/05 07:20

Sample crash report:

INFO: task syz-executor101:8474 blocked for more than 143 seconds.
      Not tainted 5.14.0-rc2-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor101 state:D stack:27408 pid: 8474 ppid:  8473 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4683 [inline]
 __schedule+0x93a/0x26f0 kernel/sched/core.c:5940
 schedule+0xd3/0x270 kernel/sched/core.c:6019
 schedule_timeout+0x1db/0x2a0 kernel/time/timer.c:1854
 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+0x176/0x280 kernel/sched/completion.c:138
 flush_workqueue+0x3ff/0x1600 kernel/workqueue.c:2839
 nbd_start_device_ioctl drivers/block/nbd.c:1350 [inline]
 __nbd_ioctl drivers/block/nbd.c:1411 [inline]
 nbd_ioctl+0x60e/0xa50 drivers/block/nbd.c:1451
 blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:585
 block_ioctl+0xf9/0x140 fs/block_dev.c:1602
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl fs/ioctl.c:1055 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:1055
 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+0x44/0xae
RIP: 0033:0x444279
RSP: 002b:00007ffc8db35ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 0000000000444279
RDX: 00000000ffffffff RSI: 000000000000ab03 RDI: 0000000000000005
RBP: 0000000000000000 R08: 00007ffc8db35e48 R09: 00007ffc8db35e48
R10: 00007ffc8db35e48 R11: 0000000000000246 R12: 0000000000403590
R13: 431bde82d7b634db R14: 00000000004b2018 R15: 00000000004004a0

Showing all locks held in the system:
2 locks held by kworker/u4:3/83:
1 lock held by khungtaskd/1649:
 #0: ffffffff8b97b9c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
2 locks held by kworker/u5:0/2035:
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:620 [inline]
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: ffff888019337938 ((wq_completion)knbd0-recv){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2247
 #1: ffffc900077dfdb0 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2251
1 lock held by in:imklog/8376:
 #0: ffff888023782870 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:974

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

NMI backtrace for cpu 0
CPU: 0 PID: 1649 Comm: khungtaskd Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 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:210 [inline]
 watchdog+0xd0a/0xfc0 kernel/hung_task.c:295
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 83 Comm: kworker/u4:3 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:task_irq_context kernel/locking/lockdep.c:4523 [inline]
RIP: 0010:__lock_acquire+0x315/0x54a0 kernel/locking/lockdep.c:4953
Code: 00 00 00 fc ff df 48 89 f1 48 89 74 24 40 49 89 44 24 18 65 8b 05 63 50 a7 7e 85 c0 0f 95 c0 48 c1 e9 03 83 e6 07 0f b6 0c 11 <48> 89 f2 0f b6 c0 83 c2 03 01 c0 38 ca 7c 08 84 c9 0f 85 70 12 00
RSP: 0018:ffffc9000104f790 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffff8880109ae138 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000004 RDI: ffff888014b88ac8
RBP: 0000000000000000 R08: 1ffff11002971156 R09: 0000000000000000
R10: 0000000000000000 R11: 000000000000003f R12: ffff888014b88ab8
R13: ffff888014b88000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec49b53000 CR3: 000000000b68e000 CR4: 0000000000350ee0
Call Trace:
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:354 [inline]
 __get_locked_pte+0x2b6/0x4d0 mm/memory.c:1736
 get_locked_pte include/linux/mm.h:2051 [inline]
 __text_poke+0x1ab/0x8c0 arch/x86/kernel/alternative.c:817
 text_poke_bp_batch+0x3d7/0x560 arch/x86/kernel/alternative.c:1178
 text_poke_flush arch/x86/kernel/alternative.c:1268 [inline]
 text_poke_flush arch/x86/kernel/alternative.c:1265 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1275
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:145
 jump_label_update+0x1d5/0x430 kernel/jump_label.c:830
 static_key_enable_cpuslocked+0x1b1/0x260 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 toggle_allocation_gate mm/kfence/core.c:623 [inline]
 toggle_allocation_gate+0x100/0x390 mm/kfence/core.c:615
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Crashes (8):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-kasan-gce-root	2021/07/23 11:54	upstream	9bead1b58c4c	bc5f1d88	.config	log	report	syz	C		INFO: task hung in nbd_ioctl
ci-upstream-kasan-gce-smack-root	2021/02/16 06:35	upstream	f40ddce88593	98682e5e	.config	log	report	syz	C		INFO: task hung in nbd_ioctl
ci-upstream-kasan-gce-selinux-root	2020/09/29 09:51	upstream	fb0155a09b02	1b88c6d5	.config	log	report	syz
ci-upstream-kasan-gce-root	2020/09/28 04:35	upstream	a1bffa48745a	5dd8aee8	.config	log	report	syz
ci-upstream-kasan-gce-root	2021/05/05 08:04	upstream	d2b6f8a17919	06c27ff5	.config	log	report			info	INFO: task hung in nbd_ioctl
ci-upstream-kasan-gce-smack-root	2021/04/09 13:26	upstream	4fa56ad0d12e	6a81331a	.config	log	report			info	INFO: task hung in nbd_ioctl
ci-upstream-kasan-gce-selinux-root	2021/02/18 20:23	upstream	f40ddce88593	14052202	.config	log	report			info	INFO: task hung in nbd_ioctl
ci-upstream-kasan-gce-smack-root	2021/02/16 04:14	upstream	f40ddce88593	98682e5e	.config	log	report			info	INFO: task hung in nbd_ioctl