INFO: task hung in do

[upstream] INFO: task hung in do_exit
Status: moderation: reported on 2018/04/23 01:02
Reported-by: syzbot+8a19c77ce070f0d4d3bb@syzkaller.appspotmail.com
First: 87d, last: 87d

Sample crash report:

INFO: task syz-executor5:10770 blocked for more than 120 seconds.
      Not tainted 4.16.0+ #9
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D23872 10770   4545 0x80000004
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x801/0x1e30 kernel/sched/core.c:3490
 schedule+0xef/0x430 kernel/sched/core.c:3549
 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline]
 rwsem_down_read_failed+0x400/0x6e0 kernel/locking/rwsem-xadd.c:286
 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 __down_read arch/x86/include/asm/rwsem.h:83 [inline]
 down_read+0xbd/0x1b0 kernel/locking/rwsem.c:26
 exit_mm kernel/exit.c:510 [inline]
 do_exit+0x58e/0x2730 kernel/exit.c:852
 do_group_exit+0x16f/0x430 kernel/exit.c:968
 get_signal+0x886/0x1960 kernel/signal.c:2469
 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4553ca
RSP: 002b:0000000000a3e778 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00000000004553ca
RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000
RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000

Showing all locks held in the system:
2 locks held by khungtaskd/891:
 #0: 00000000e31ead2c (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0: 00000000e31ead2c (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249
 #1: 000000007e45af2d (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470
2 locks held by getty/4463:
 #0: 00000000194cce9b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000abb8dc56 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4464:
 #0: 00000000cfd30728 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000009eb63178 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4465:
 #0: 000000008e108a86 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000032b5d725 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4466:
 #0: 00000000fed759c7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000036186c4e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4467:
 #0: 0000000045885fc9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000006333181e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4468:
 #0: 00000000b3f77cf8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000c0bc3c04 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4469:
 #0: 0000000028802457 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000d695486a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
1 lock held by syz-executor5/10770:
 #0: 00000000954b5527 (&mm->mmap_sem){++++}, at: exit_mm kernel/exit.c:510 [inline]
 #0: 00000000954b5527 (&mm->mmap_sem){++++}, at: do_exit+0x58e/0x2730 kernel/exit.c:852
2 locks held by syz-executor5/10771:
 #0: 00000000bcaa55e3 (sk_lock-AF_INET){+.+.}, at: lock_sock include/net/sock.h:1469 [inline]
 #0: 00000000bcaa55e3 (sk_lock-AF_INET){+.+.}, at: sk_stream_wait_memory+0x920/0x1260 net/core/stream.c:149
 #1: 00000000954b5527 (&mm->mmap_sem){++++}, at: __do_page_fault+0xacc/0xe40 arch/x86/mm/fault.c:1335
1 lock held by syz-executor5/10871:
 #0: 00000000954b5527 (&mm->mmap_sem){++++}, at: vm_mmap_pgoff+0x1a1/0x2a0 mm/util.c:353

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

NMI backtrace for cpu 1
CPU: 1 PID: 891 Comm: khungtaskd Not tainted 4.16.0+ #9
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+0x1b9/0x294 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
 check_hung_task kernel/hung_task.c:132 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
 watchdog+0xc10/0xf60 kernel/hung_task.c:249
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54

All crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci-upstream-net-kasan-gce	2018/04/20 23:48	net-next	0263ea5cddedd84c111b55d33a8ec94740d1c8d3	cc402841ba1e067327a4adaf0a65335e47b5e83c	.config	log	report			["akpm@linux-foundation.org" "keescook@chromium.org" "linux-kernel@vger.kernel.org" "mingo@kernel.org" "paulmck@linux.vnet.ibm.com" "viro@zeniv.linux.org.uk"]