INFO: task syz-executor3:11083 blocked for more than 120 seconds.
      Not tainted 4.9.107-g42a730a #45
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D28584 11083   3893 0x00000004
 ffff880184756000 ffff8801c757ea00 ffff8801da3e24c0 ffff8801c59d0000
 ffff8801db321c18 ffff8801b81af580 ffffffff839e8c1d ffffffff81235b37
 0000000000000000 ffff8801847568c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea21f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f4644>] rwsem_down_read_failed+0x1e4/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81ee8558>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff839f3572>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff839f3572>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff8157b179>] get_super.part.9+0x119/0x1f0 fs/super.c:665
 [<ffffffff8157b27b>] get_super+0x2b/0x50 include/linux/spinlock.h:302
 [<ffffffff816340f7>] fsync_bdev+0x17/0xc0 fs/block_dev.c:214
 [<ffffffff81e5be05>] invalidate_partition+0x35/0x60 block/genhd.c:1412
 [<ffffffff81e653a7>] drop_partitions block/partition-generic.c:423 [inline]
 [<ffffffff81e653a7>] rescan_partitions+0xc7/0x660 block/partition-generic.c:446
 [<ffffffff81e56884>] __blkdev_reread_part+0x164/0x1f0 block/ioctl.c:170
 [<ffffffff81e56936>] blkdev_reread_part+0x26/0x40 block/ioctl.c:190
 [<ffffffff825c734c>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:637
 [<ffffffff825c7dde>] loop_set_status+0xa7e/0xfe0 drivers/block/loop.c:1171
 [<ffffffff825c87df>] loop_set_status64+0xbf/0x110 drivers/block/loop.c:1280
 [<ffffffff825cafe6>] lo_ioctl+0x406/0x1aa0 drivers/block/loop.c:1370
 [<ffffffff81e57ea6>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<ffffffff81e57ea6>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
 [<ffffffff8163300e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
 [<ffffffff815b301c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b301c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b301c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b409f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b409f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] 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: [<ffffffff81366b6c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81366b6c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff814261d0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3773:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7cc2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82120162>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
3 locks held by syz-executor3/11083:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cac6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81e5692e>] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189
 #2:  (&type->s_umount_key#54){++++..}, at: [<ffffffff8157b179>] get_super.part.9+0x119/0x1f0 fs/super.c:665
1 lock held by syz-executor3/11139:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cac6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor3/11140:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8163171c>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
1 lock held by syz-executor3/11141:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cac6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor3/11143:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cac6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by blkid/11084:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825cac6b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.107-g42a730a #45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d84b7d08 ffffffff81eb42a9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b96a0 ffff8801d84b7d40
 ffffffff81ebf5a7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb42a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb42a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf5a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf53a>] 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
 [<ffffffff81367104>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81367104>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367104>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367104>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9cdc>] 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: 11076 Comm: syz-executor0 Not tainted 4.9.107-g42a730a #45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801b6c9c800 task.stack: ffff8801b6d38000
RIP: 0010:[<ffffffff811bb5aa>] 
c [<ffffffff811bb5aa>] __might_sleep+0x1a/0x1a0 kernel/sched/core.c:7936
RSP: 0018:ffff8801b6d3f608  EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffea000609ee00 RCX: ffffc90002fc1000
RDX: 0000000000000000 RSI: 00000000000001c4 RDI: ffffffff83ca4920
RBP: ffff8801b6d3f620 R08: ffff8801b6c9d110 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff10036d93a1d R12: 0000000000000007
R13: 00000000000001c4 R14: 0000000000000000 R15: ffff8801d9c17688
FS:  00007fb252807700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0f60488000 CR3: 00000001bffe9000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000007
c dffffc0000000000
c 0000000002420848
c ffff8801b6d3f678
c
 ffffffff8143a7ad
c ffffffff8162483a
c 000002000609ee00
c fffffbfff098c420
c
 0000000000000140
c 0000000000000003
c ffffea000609ee1c
c ffff8801d9c17688
c
Call Trace:
 [<ffffffff8143a7ad>] lock_page include/linux/pagemap.h:452 [inline]
 [<ffffffff8143a7ad>] pagecache_get_page+0x3bd/0x720 mm/filemap.c:1216
 [<ffffffff81625729>] find_or_create_page include/linux/pagemap.h:309 [inline]
 [<ffffffff81625729>] grow_dev_page fs/buffer.c:1005 [inline]
 [<ffffffff81625729>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff81625729>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff81625729>] __getblk_gfp+0x249/0x710 fs/buffer.c:1386
 [<ffffffff8162900d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818b7238>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818b7238>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818b9ec1>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818b9ec1>] fat_get_short_entry+0x131/0x2a0 fs/fat/dir.c:876
 [<ffffffff818c1e27>] fat_subdirs+0xc7/0x190 fs/fat/dir.c:942
 [<ffffffff818d2139>] fat_read_root fs/fat/inode.c:1402 [inline]
 [<ffffffff818d2139>] fat_fill_super+0x1cf9/0x3550 fs/fat/inode.c:1832
 [<ffffffff818de48e>] msdos_fill_super+0x2e/0x40 fs/fat/namei_msdos.c:654
 [<ffffffff8157c857>] mount_bdev+0x2c7/0x390 fs/super.c:1100
 [<ffffffff818de454>] msdos_mount+0x34/0x40 fs/fat/namei_msdos.c:661
 [<ffffffff8157e5dc>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815ddda1>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e56c9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e56c9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e56c9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e841e>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e841e>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c<49> 
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c