syzbot

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kernel BUG at fs/ext4/inode.c:2630!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 6446 Comm: syz-executor599 Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801cb368000 task.stack: ffff8801b5a38000
RIP: 0010:[<ffffffff81740088>]  [<ffffffff81740088>] mpage_prepare_extent_to_map+0x7f8/0xa40 fs/ext4/inode.c:2630
RSP: 0018:ffff8801b5a3f800  EFLAGS: 00010293
RAX: ffff8801cb368000 RBX: ffffea0007018200 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81740088 RDI: ffffea0007018208
RBP: ffff8801b5a3f9c8 R08: ffff8801cb368938 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff1003966d122 R12: 0000000000000001
R13: 0000000000000000 R14: ffff8801b5a3fb30 R15: dffffc0000000000
FS:  0000000000889880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fac6e747e78 CR3: 00000001ba86b000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 1ffff10036b47f10 ffff8801b5a3fb38 ffff8801b5a3f8a0 ffff8801b5a3fb40
 00000000cb3688c0 ffff8801bee08c00 000000090000000c 7fffffffffffffff
 ffff8801b5a3f8e0 ffff8801b5a3fb48 ffffea0007018210 ffffed0036b47f67
Call Trace:
 [<ffffffff81750f59>] ext4_writepages+0xdb9/0x2e50 fs/ext4/inode.c:2792
 [<ffffffff8145ed0f>] do_writepages+0xef/0x1d0 mm/page-writeback.c:2347
 [<ffffffff8143ccd3>] __filemap_fdatawrite_range+0x1b3/0x250 mm/filemap.c:390
 [<ffffffff8143cef3>] __filemap_fdatawrite mm/filemap.c:398 [inline]
 [<ffffffff8143cef3>] filemap_flush+0x23/0x30 mm/filemap.c:423
 [<ffffffff81746459>] ext4_alloc_da_blocks+0xd9/0x330 fs/ext4/inode.c:3169
 [<ffffffff8172c30f>] ext4_release_file+0x1ff/0x2e0 fs/ext4/file.c:42
 [<ffffffff815782e3>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff81578805>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119839c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff839f9f53>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: ff 48 8b 75 d0 65 48 33 34 25 28 00 00 00 0f 85 50 02 00 00 48 81 c4 a0 01 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 e8 e9 c1 ff <0f> 0b e8 e1 e9 c1 ff 8b 95 18 ff ff ff 85 d2 75 7a e8 d2 e9 c1 
RIP  [<ffffffff81740088>] mpage_prepare_extent_to_map+0x7f8/0xa40 fs/ext4/inode.c:2630
 RSP <ffff8801b5a3f800>
---[ end trace 55d0fb3bf5735192 ]---