F2FS-fs (loop7): Magic Mismatch, valid(0xf2f52010) - read(0x0)
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WARNING: CPU: 0 PID: 19841 at ./include/linux/kref.h:46 kref_get include/linux/kref.h:46 [inline]
WARNING: CPU: 0 PID: 19841 at ./include/linux/kref.h:46 kobject_get+0xd1/0xf0 lib/kobject.c:598
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 19841 Comm: blkid Not tainted 4.9.96-g71fce1e #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff88019a52f5e8 ffffffff81eb0b69 ffffffff83a484a0 00000000ffffffff
 0000000000000000 0000000000000000 000000000000002e ffff88019a52f6a8
 ffffffff8141f975 0000000041b58ab3 ffffffff841b8030 ffffffff8141f7b6
Call Trace:
 [<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8141f975>] panic+0x1bf/0x3bc kernel/panic.c:179
 [<ffffffff8141fc61>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff8113461c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff81eb7341>] kref_get include/linux/kref.h:46 [inline]
 [<ffffffff81eb7341>] kobject_get+0xd1/0xf0 lib/kobject.c:598
 [<ffffffff81e577fa>] get_disk+0x8a/0xd0 block/genhd.c:1344
 [<ffffffff81e57b4a>] get_gendisk+0x16a/0x2d0 block/genhd.c:724
 [<ffffffff8162ec81>] __blkdev_get+0x351/0xd60 fs/block_dev.c:1262
 [<ffffffff81631f2a>] blkdev_get+0x2da/0x920 fs/block_dev.c:1416
 [<ffffffff81632785>] blkdev_open+0x1a5/0x250 fs/block_dev.c:1571
 [<ffffffff81567583>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff8156ad6c>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a1ea8>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a1ea8>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815a8fa7>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156b77d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156ba5d>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156ba5d>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f3313>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..