------------[ cut here ]------------
WARNING: CPU: 1 PID: 3268 at fs/buffer.c:1197 __brelse fs/buffer.c:1197 [inline]
WARNING: CPU: 1 PID: 3268 at fs/buffer.c:1197 __brelse+0x6c/0x80 fs/buffer.c:1191
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2117 at fs/buffer.c:1197 __brelse fs/buffer.c:1197 [inline]
WARNING: CPU: 1 PID: 2117 at fs/buffer.c:1197 __brelse+0x6c/0x80 fs/buffer.c:1191
VFS: brelse: Trying to free free buffer
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 2117 Comm: syz-executor.0 Not tainted 4.9.167+ #36
 ffff8801a8a07560 ffffffff81b4f011 ffff8801a8a07600 ffffffff82a39ba0
 00000000ffffffff 0000000000000001 0000000000000009 ffff8801a8a07640
 ffffffff813f91aa 0000000041b58ab3 ffffffff82e2ec1a ffffffff813f8fd1
Call Trace:
 [<0000000050bb957f>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000050bb957f>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000008b0e434d>] panic+0x1d9/0x3bd kernel/panic.c:180
 [<000000001ff680c4>] __warn.cold+0x2f/0x2f kernel/panic.c:546
 [<0000000023e7e972>] warn_slowpath_fmt+0xc2/0x100 kernel/panic.c:569
 [<00000000cd765afe>] __brelse fs/buffer.c:1197 [inline]
 [<00000000cd765afe>] __brelse+0x6c/0x80 fs/buffer.c:1191
 [<00000000396bcfb0>] bh_lru_install+0x25e/0x310 fs/buffer.c:1313
 [<0000000047be9fa4>] __find_get_block+0x2b2/0x4c0 fs/buffer.c:1363
 [<0000000035368aca>] __getblk_gfp+0x38/0x700 fs/buffer.c:1383
 [<000000007b26159d>] sb_getblk include/linux/buffer_head.h:318 [inline]
 [<000000007b26159d>] ext4_getblk+0x16a/0x490 fs/ext4/inode.c:950
 [<00000000c845fdf1>] ext4_find_entry+0xa43/0x12b0 fs/ext4/namei.c:1420
 [<00000000d309d2b8>] ext4_rmdir fs/ext4/namei.c:2893 [inline]
 [<00000000d309d2b8>] ext4_rmdir+0x108/0xab0 fs/ext4/namei.c:2875
 [<000000006f082e06>] vfs_rmdir2 fs/namei.c:3932 [inline]
 [<000000006f082e06>] vfs_rmdir2+0x21b/0x410 fs/namei.c:3910
 [<00000000e4599997>] do_rmdir+0x2c9/0x3a0 fs/namei.c:3998
 [<0000000066a6c3dd>] SYSC_rmdir fs/namei.c:4016 [inline]
 [<0000000066a6c3dd>] SyS_rmdir+0x1b/0x20 fs/namei.c:4014
 [<0000000069874187>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<00000000b1d10659>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Kernel Offset: disabled
Rebooting in 86400 seconds..