RAX: ffffffffffffffda RBX: 00007fbd035756d4 RCX: 0000000000455979
RDX: 000000000000c4d9 RSI: 0000000000000001 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000200000000 R11: 0000000000000246 R12: 0000000000000014
R13: 000000000000007e R14: 00000000006f3c70 R15: 0000000000000018
BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: __read_once_size include/linux/compiler.h:197 [inline]
IP: compound_head include/linux/page-flags.h:142 [inline]
IP: PageLocked include/linux/page-flags.h:260 [inline]
IP: grow_dev_page fs/buffer.c:965 [inline]
IP: grow_buffers fs/buffer.c:1032 [inline]
IP: __getblk_slow fs/buffer.c:1059 [inline]
IP: __getblk_gfp+0x5bf/0x1620 fs/buffer.c:1339
PGD 800000014c0c3067 P4D 800000014c0c3067 PUD 1a0730067 PMD 0 
Oops: 0000 [#1] SMP PTI
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 17097 Comm: syz-executor7 Not tainted 4.16.0+ #87
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:197 [inline]
RIP: 0010:compound_head include/linux/page-flags.h:142 [inline]
RIP: 0010:PageLocked include/linux/page-flags.h:260 [inline]
RIP: 0010:grow_dev_page fs/buffer.c:965 [inline]
RIP: 0010:grow_buffers fs/buffer.c:1032 [inline]
RIP: 0010:__getblk_slow fs/buffer.c:1059 [inline]
RIP: 0010:__getblk_gfp+0x5bf/0x1620 fs/buffer.c:1339
RSP: 0018:ffff88014e7ef1c0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000
RDX: ffff88015258e198 RSI: 0000000000000000 RDI: 0000000000040000
RBP: ffff88014e7ef308 R08: 0000000000000100 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8801dbc28f50
FS:  00007fbd03575700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000093002d CR3: 00000001b6484000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 sb_getblk_gfp include/linux/buffer_head.h:334 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1281 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1378 [inline]
 ext4_ext_insert_extent+0x1a52/0x8d40 fs/ext4/extents.c:2062
 ext4_ext_map_blocks+0x68cd/0xcd20 fs/ext4/extents.c:4487
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
 ext4_map_blocks+0x1218/0x2bd0 fs/ext4/inode.c:636
 ext4_alloc_file_blocks+0x6c9/0x1370 fs/ext4/extents.c:4688
 ext4_fallocate+0x132b/0x3790 fs/ext4/extents.c:4970
 vfs_fallocate+0x9dc/0xde0 fs/open.c:319
 SYSC_fallocate+0x119/0x1d0 fs/open.c:342
 SyS_fallocate+0x64/0x90 fs/open.c:336
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x455979
RSP: 002b:00007fbd03574c68 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007fbd035756d4 RCX: 0000000000455979
RDX: 000000000000c4d9 RSI: 0000000000000001 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000200000000 R11: 0000000000000246 R12: 0000000000000014
R13: 000000000000007e R14: 00000000006f3c70 R15: 0000000000000018
Code: ff ff ff 44 89 e9 e8 11 e9 af ff 49 89 c6 4c 8b ab 20 03 00 00 8b 83 a8 0f 00 00 89 45 d0 49 8d 5e 20 4d 85 ed 0f 85 31 01 00 00 <4d> 8b 7e 20 48 89 9d e0 fe ff ff 48 89 df e8 2e 8d dd ff 48 8b 
RIP: __read_once_size include/linux/compiler.h:197 [inline] RSP: ffff88014e7ef1c0
RIP: compound_head include/linux/page-flags.h:142 [inline] RSP: ffff88014e7ef1c0
RIP: PageLocked include/linux/page-flags.h:260 [inline] RSP: ffff88014e7ef1c0
RIP: grow_dev_page fs/buffer.c:965 [inline] RSP: ffff88014e7ef1c0
RIP: grow_buffers fs/buffer.c:1032 [inline] RSP: ffff88014e7ef1c0
RIP: __getblk_slow fs/buffer.c:1059 [inline] RSP: ffff88014e7ef1c0
RIP: __getblk_gfp+0x5bf/0x1620 fs/buffer.c:1339 RSP: ffff88014e7ef1c0
CR2: 0000000000000020
---[ end trace 9b688591cf74a169 ]---