BUG: unable to handle kernel paging request in xfs_sb_read_verify

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    419593da Add linux-next specific files for 20191129
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10cecb36e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7c04b0959e75c206
dashboard link: https://syzkaller.appspot.com/bug?extid=6be2cbddaad2e32b47a0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6be2cbddaad2e32b47a0@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: unable to handle page fault for address: fffff52002e00000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 21ffee067 P4D 21ffee067 PUD aa11c067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 2938 Comm: kworker/0:2 Not tainted  
5.4.0-next-20191129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: xfs-buf/loop3 xfs_buf_ioend_work
RIP: 0010:xfs_sb_read_verify+0xf0/0x540 fs/xfs/libxfs/xfs_sb.c:691
Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 18 04 00 00 4d 8b ac 24 30 01  
00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <0f> b6 04 02 84  
c0 74 08 3c 03 0f 8e a7 03 00 00 41 8b 75 00 bf 58
RSP: 0018:ffffc90007e5faf0 EFLAGS: 00010a06
RAX: dffffc0000000000 RBX: 1ffff92000fcbf61 RCX: ffffffff82acb516
RDX: 1ffff92002e00000 RSI: ffffffff82a97e3b RDI: ffff888091bada60
RBP: ffffc90007e5fcd0 R08: ffff88809f3c2040 R09: ffffed1015cc7045
R10: ffffed1015cc7044 R11: ffff8880ae638223 R12: ffff888091bad940
R13: ffffc90017000000 R14: ffffc90007e5fca8 R15: ffff88809feb8000
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff52002e00000 CR3: 0000000069ceb000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 xfs_buf_ioend+0x3f9/0xde0 fs/xfs/xfs_buf.c:1162
 xfs_buf_ioend_work+0x19/0x20 fs/xfs/xfs_buf.c:1183
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
CR2: fffff52002e00000
---[ end trace aef83d995322cc4a ]---
RIP: 0010:xfs_sb_read_verify+0xf0/0x540 fs/xfs/libxfs/xfs_sb.c:691
Code: fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 18 04 00 00 4d 8b ac 24 30 01  
00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <0f> b6 04 02 84  
c0 74 08 3c 03 0f 8e a7 03 00 00 41 8b 75 00 bf 58
RSP: 0018:ffffc90007e5faf0 EFLAGS: 00010a06
RAX: dffffc0000000000 RBX: 1ffff92000fcbf61 RCX: ffffffff82acb516
RDX: 1ffff92002e00000 RSI: ffffffff82a97e3b RDI: ffff888091bada60
RBP: ffffc90007e5fcd0 R08: ffff88809f3c2040 R09: ffffed1015cc7045
R10: ffffed1015cc7044 R11: ffff8880ae638223 R12: ffff888091bad940
R13: ffffc90017000000 R14: ffffc90007e5fca8 R15: ffff88809feb8000
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff52002e00000 CR3: 0000000069ceb000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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