syzbot

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WARNING: CPU: 2 PID: 24763 at mm/shmem.c:1420 shmem_evict_inode+0x8ee/0xbe0 mm/shmem.c:1420
Modules linked in:
CPU: 2 UID: 0 PID: 24763 Comm: syz.5.13179 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:shmem_evict_inode+0x8ee/0xbe0 mm/shmem.c:1420
Code: fe e8 66 51 be ff 45 85 ff 75 ac e8 1c 56 be ff 48 8b 74 24 28 48 8b 7c 24 30 e8 bd da 96 ff e9 e5 fd ff ff e8 03 56 be ff 90 <0f> 0b 90 e9 51 f9 ff ff e8 f5 55 be ff 4c 89 e2 48 b8 00 00 00 00
RSP: 0018:ffffc9000358fab8 EFLAGS: 00010246
RAX: 0000000000080000 RBX: ffff88804dcdc958 RCX: ffffc90026b81000
RDX: 0000000000080000 RSI: ffffffff81fcb28d RDI: 0000000000000007
RBP: ffffc9000358fbe0 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000000 R12: 0000000000000008
R13: 0000000000000000 R14: ffff88804dcdc988 R15: ffff88804dcdc848
FS:  0000000000000000(0000) GS:ffff8880976c3000(0063) knlGS:00000000f5516b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f74327b8 CR3: 000000001b543000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 evict+0x3e3/0x920 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput fs/inode.c:1923 [inline]
 iput+0x521/0x880 fs/inode.c:1909
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:466
 __dentry_kill+0x1d0/0x600 fs/dcache.c:669
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:911
 dput+0x1f/0x30 fs/dcache.c:901
 __fput+0x51c/0xb70 fs/file_table.c:476
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 __do_fast_syscall_32+0x2ac/0x3a0 arch/x86/entry/syscall_32.c:309
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:331
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7ff2579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f551655c EFLAGS: 00000296 ORIG_RAX: 00000000000000c0
RAX: 0000000080000000 RBX: 0000000080000000 RCX: 0000000000b36000
RDX: 0000000000000002 RSI: 0000000000008031 RDI: 00000000ffffffff
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi