------------[ cut here ]------------
WARNING: CPU: 1 PID: 21546 at fs/buffer.c:1197 __brelse fs/buffer.c:1197 [inline]
WARNING: CPU: 1 PID: 21546 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: 21546 Comm: syz-executor.5 Not tainted 4.9.166+ #35
 ffff880199d4f8b0 ffffffff81b4ef81 ffff880199d4fa00 ffffffff82a39ba0
 00000000ffffffff 0000000000000001 0000000000000009 ffff880199d4f990
 ffffffff813f91aa 0000000041b58ab3 ffffffff82e2ec1a ffffffff813f8fd1
Call Trace:
 [<000000004699702a>] __dump_stack lib/dump_stack.c:15 [inline]
 [<000000004699702a>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000002ebe1968>] panic+0x1d9/0x3bd kernel/panic.c:180
 [<00000000319f0309>] __warn.cold+0x2f/0x2f kernel/panic.c:546
 [<000000008b834e0d>] warn_slowpath_fmt+0xc2/0x100 kernel/panic.c:569
 [<00000000aa8a5dee>] __brelse fs/buffer.c:1197 [inline]
 [<00000000aa8a5dee>] __brelse+0x6c/0x80 fs/buffer.c:1191
 [<00000000e613fa17>] brelse include/linux/buffer_head.h:288 [inline]
 [<00000000e613fa17>] ext4_ind_remove_space+0xfa3/0x13e0 fs/ext4/indirect.c:1390
 [<00000000ae1da4a1>] ext4_punch_hole+0xb28/0x1000 fs/ext4/inode.c:4104
 [<000000008bd2ba50>] ext4_fallocate+0x34e/0x2070 fs/ext4/extents.c:4951
 [<00000000254a62d4>] vfs_fallocate+0x407/0x6a0 fs/open.c:329
 [<000000006d4c9fa1>] SYSC_fallocate fs/open.c:352 [inline]
 [<000000006d4c9fa1>] SyS_fallocate+0x52/0x90 fs/open.c:346
 [<00000000eb545e82>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<00000000448e03a7>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Kernel Offset: disabled
Rebooting in 86400 seconds..