BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
PGD 80000000b367b067 P4D 80000000b367b067 PUD 77178067 PMD 0 
Oops: 0000 [#1] SMP PTI
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 13085 Comm: syz-executor3 Not tainted 4.17.0+ #8
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:272 [inline]
RIP: 0010:grow_dev_page fs/buffer.c:942 [inline]
RIP: 0010:grow_buffers fs/buffer.c:1009 [inline]
RIP: 0010:__getblk_slow fs/buffer.c:1036 [inline]
RIP: 0010:__getblk_gfp+0x5bf/0x1630 fs/buffer.c:1316
RSP: 0018:ffff88008575f648 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000
RDX: ffff8801132d88d8 RSI: 0000000000000000 RDI: 0000000000023045
RBP: ffff88008575f790 R08: 0000000000000100 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff865758f0 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8801db4288d0
FS:  00007f125d181700(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020e33fe0 CR3: 000000007518a000 CR4: 00000000001406e0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 __bread_gfp+0x11b/0x850 fs/buffer.c:1352
 sb_bread include/linux/buffer_head.h:309 [inline]
 ext4_xattr_get_block fs/ext4/xattr.c:2282 [inline]
 ext4_xattr_set_credits+0x246/0x5e0 fs/ext4/xattr.c:2464
 ext4_xattr_set+0x24e/0x570 fs/ext4/xattr.c:2500
 ext4_xattr_user_set+0x19e/0x1d0 fs/ext4/xattr_user.c:40
 __vfs_setxattr+0x7fa/0x850 fs/xattr.c:150
 __vfs_setxattr_noperm+0x340/0x900 fs/xattr.c:181
 vfs_setxattr fs/xattr.c:224 [inline]
 setxattr+0x8c3/0x9e0 fs/xattr.c:453
 __do_sys_fsetxattr fs/xattr.c:508 [inline]
 __se_sys_fsetxattr+0x2b0/0x3a0 fs/xattr.c:497
 __x64_sys_fsetxattr+0x15d/0x1b0 fs/xattr.c:497
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x455b29
RSP: 002b:00007f125d180c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000be
RAX: ffffffffffffffda RBX: 00007f125d1816d4 RCX: 0000000000455b29
RDX: 00000000200002c0 RSI: 0000000020000280 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000398 R11: 0000000000000246 R12: 0000000000000015
R13: 00000000004bbca6 R14: 00000000004c89c8 R15: 0000000000000001
Code: ff ff ff 44 89 e9 e8 f1 80 ad 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 35 01 00 00 <4d> 8b 7e 20 48 89 9d e0 fe ff ff 48 89 df e8 0e 3c dc ff 48 8b 
RIP: __read_once_size include/linux/compiler.h:197 [inline] RSP: ffff88008575f648
RIP: compound_head include/linux/page-flags.h:142 [inline] RSP: ffff88008575f648
RIP: PageLocked include/linux/page-flags.h:272 [inline] RSP: ffff88008575f648
RIP: grow_dev_page fs/buffer.c:942 [inline] RSP: ffff88008575f648
RIP: grow_buffers fs/buffer.c:1009 [inline] RSP: ffff88008575f648
RIP: __getblk_slow fs/buffer.c:1036 [inline] RSP: ffff88008575f648
RIP: __getblk_gfp+0x5bf/0x1630 fs/buffer.c:1316 RSP: ffff88008575f648
CR2: 0000000000000020
---[ end trace 558edc2f060d0fb3 ]---