b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=4, b_blocknr=32
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
INFO: task syz-executor0:18901 blocked for more than 120 seconds.
      Not tainted 4.9.108-gb7d377b #47
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29384 18901   3835 0x00000004
 ffff8801d4958000 ffff8801d84464c0 ffff88018392b9c0 ffff8801d4ebc800
 ffff8801db221c18 ffff880185a67728 ffffffff839e8aed ffffffff812355f7
 0000000000000000 ffff8801d49588c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea0ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f5728>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f5728>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8107>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f34fc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f34fc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8156a6e8>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff8156a6e8>] do_truncate2+0x128/0x1f0 fs/open.c:61
 [<ffffffff815a62ee>] handle_truncate fs/namei.c:2990 [inline]
 [<ffffffff815a62ee>] do_last fs/namei.c:3419 [inline]
 [<ffffffff815a62ee>] path_openat+0x251e/0x3590 fs/namei.c:3534
 [<ffffffff815ab627>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156ddfd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e157>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e157>] SyS_open fs/open.c:1085 [inline]
 [<ffffffff8156e157>] SYSC_creat fs/open.c:1110 [inline]
 [<ffffffff8156e157>] SyS_creat+0x27/0x30 fs/open.c:1108
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f99d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3684:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d803c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3780:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211fce2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:6/4825:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305ca3f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
2 locks held by syz-executor0/18901:
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815e08df>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815e08df>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#21){++++++}, at: [<ffffffff8156a6e8>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){++++++}, at: [<ffffffff8156a6e8>] do_truncate2+0x128/0x1f0 fs/open.c:61
2 locks held by syz-executor0/18903:
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff8156865b>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff8156865b>] vfs_fallocate+0x2fb/0x600 fs/open.c:328
 #1:  (&sb->s_type->i_mutex_key#21){++++++}, at: [<ffffffff818c7bde>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#21){++++++}, at: [<ffffffff818c7bde>] fat_fallocate+0x10e/0x2d0 fs/fat/file.c:249

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86b7d08 ffffffff81eb3e29 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b96a0 ffff8801d86b7d40
 ffffffff81ebf127 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb3e29>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3e29>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf127>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf0ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 18918 Comm: syz-executor3 Not tainted 4.9.108-gb7d377b #47
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801b7419800 task.stack: ffff88018b990000
RIP: 0010:[<ffffffff821506d3>] 
c [<ffffffff821506d3>] outb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff821506d3>] 
c [<ffffffff821506d3>] io_serial_out+0x73/0x90 drivers/tty/serial/8250/8250_port.c:420
RSP: 0000:ffff88018b9977b0  EFLAGS: 00000002
RAX: 0000000000000033 RBX: 00000000000003f8 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: ffffffff82150676 RDI: ffffffff864aaeb8
RBP: ffff88018b9977c8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff864aae80
R13: 0000000000000033 R14: dffffc0000000000 R15: 0000000000000033
FS:  0000000001a7a940(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c420f91000 CR3: 00000001865bc000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff864aae80
c 0000000000000033
c ffffffff82152350
c ffff88018b9977e8
c
 ffffffff8215239b
c ffffffff85aec1a6
c ffffffff864aae80
c ffff88018b997828
c
 ffffffff8213ab99
c ffffffff85aec1d0
c ffffffff864aae80
c ffffffff864ab0a0
c
Call Trace:
 [<ffffffff8215239b>] serial_port_out include/linux/serial_core.h:262 [inline]
 [<ffffffff8215239b>] serial8250_console_putchar+0x4b/0x60 drivers/tty/serial/8250/8250_port.c:3105
 [<ffffffff8213ab99>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215e588>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3170
 [<ffffffff8214b0ef>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125bc5d>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8125ea5f>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff8125f5b8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff8125f928>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff8125f94d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff8142ca8c>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142ca8c>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff839d2900>] __ip_vs_init.cold.37+0x36/0x45 net/netfilter/ipvs/ip_vs_core.c:2243
 [<ffffffff8305b78c>] ops_init+0xac/0x380 net/core/net_namespace.c:111
 [<ffffffff8305bc19>] setup_net+0x1b9/0x3f0 net/core/net_namespace.c:291
 [<ffffffff8305d0b9>] copy_net_ns+0x189/0x290 net/core/net_namespace.c:408
 [<ffffffff811a06bc>] create_new_namespaces+0x51c/0x730 kernel/nsproxy.c:106
 [<ffffffff811a0eb5>] unshare_nsproxy_namespaces+0xa5/0x1d0 kernel/nsproxy.c:205
 [<ffffffff81135599>] SYSC_unshare kernel/fork.c:2244 [inline]
 [<ffffffff81135599>] SyS_unshare+0x319/0x710 kernel/fork.c:2194
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f99d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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