syzbot

raw: 02fffc0000001038 ffffea0006d24448 ffffea0006d987c8 ffff8801a7b26af8
raw: 0000000000000018 ffff8801a79422a0 00000003ffffffff ffff8801d9a44c80
page dumped because: VM_BUG_ON_PAGE(page_to_pgoff(page) != index)
page->mem_cgroup:ffff8801d9a44c80
------------[ cut here ]------------
kernel BUG at mm/shmem.c:815!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 4451 Comm: syz-executor101 Not tainted 4.18.0-rc3-next-20180706+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:shmem_undo_range+0xdaa/0x29a0 mm/shmem.c:815
Code: 00 0f 85 bd 19 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 a5 f0 d6 ff 48 c7 c6 e0 32 f1 87 4c 89 e7 e8 16 10 05 00 <0f> 0b e8 8f f0 d6 ff 49 8d 7c 24 20 48 89 f8 48 c1 e8 03 80 3c 18 
RSP: 0018:ffff8801cb3feb80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81aaab95 RDI: ffffed003967fd60
RBP: ffff8801cb3ff2f8 R08: ffff8801c245e500 R09: ffffed003b5c4fc0
R10: ffffed003b5c4fc0 R11: ffff8801dae27e07 R12: ffffea0006d98780
R13: ffff8801cb3ff2d0 R14: 0000000000000004 R15: 0000000000000018
FS:  0000000001646880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000001c277c000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 shmem_truncate_range+0x27/0xa0 mm/shmem.c:971
 shmem_evict_inode+0x3b2/0xcb0 mm/shmem.c:1071
 evict+0x4ae/0x990 fs/inode.c:558
 iput_final fs/inode.c:1508 [inline]
 iput+0x635/0xaa0 fs/inode.c:1534
 dentry_unlink_inode+0x4ae/0x640 fs/dcache.c:377
 __dentry_kill+0x44c/0x7a0 fs/dcache.c:569
 dentry_kill+0xc9/0x5a0 fs/dcache.c:688
 dput.part.26+0x66b/0x7a0 fs/dcache.c:849
 dput+0x15/0x20 fs/dcache.c:831
 __fput+0x558/0x930 fs/file_table.c:235
 ____fput+0x15/0x20 fs/file_table.c:251
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:192 [inline]
 exit_to_usermode_loop+0x313/0x370 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4011f0
Code: 01 f0 ff ff 0f 83 90 0a 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 9d 0b 2d 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 64 0a 00 00 c3 48 83 ec 08 e8 1a 01 00 00 
RSP: 002b:00007ffdb97d01b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000004011f0
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 000000000000000c
R10: 0000000000000064 R11: 0000000000000246 R12: 0000000000000006
R13: 0000000000000005 R14: 0000000000000005 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace ba3448a6a36817df ]---
RIP: 0010:shmem_undo_range+0xdaa/0x29a0 mm/shmem.c:815
Code: 00 0f 85 bd 19 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 a5 f0 d6 ff 48 c7 c6 e0 32 f1 87 4c 89 e7 e8 16 10 05 00 <0f> 0b e8 8f f0 d6 ff 49 8d 7c 24 20 48 89 f8 48 c1 e8 03 80 3c 18 
RSP: 0018:ffff8801cb3feb80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81aaab95 RDI: ffffed003967fd60
RBP: ffff8801cb3ff2f8 R08: ffff8801c245e500 R09: ffffed003b5c4fc0
R10: ffffed003b5c4fc0 R11: ffff8801dae27e07 R12: ffffea0006d98780
R13: ffff8801cb3ff2d0 R14: 0000000000000004 R15: 0000000000000018
FS:  0000000001646880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000001c277c000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400