Hello,

syzbot hit the following crash on upstream commit
e237f98a9c134c3d600353f21e07db915516875b (Mon Feb 5 21:35:56 2018 +0000)
Merge tag 'xfs-4.16-merge-5' of  
git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: syzbot+7525b19f9531f76b8b1e@syzkaller.appspotmail.com
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audit: type=1400 audit(1517939984.452:7): avc:  denied  { map } for   
pid=4159 comm="syzkaller032522" path="/root/syzkaller032522586" dev="sda1"  
ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
WARNING: CPU: 0 PID: 4159 at mm/slab_common.c:1012 kmalloc_slab+0x5d/0x70  
mm/slab_common.c:1012
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4159 Comm: syzkaller032522 Not tainted 4.15.0+ #299
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x211/0x2d0 lib/bug.c:184
  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
  fixup_bug arch/x86/kernel/traps.c:247 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
  invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:984
RIP: 0010:kmalloc_slab+0x5d/0x70 mm/slab_common.c:1012
RSP: 0018:ffff8801b128f510 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801cb661180 RCX: ffffffff81726847
RDX: 1ffff100397e0e02 RSI: 0000000000000000 RDI: 00000000b0d80008
RBP: ffff8801b128f510 R08: 1ffff10036251e16 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cbf07010
R13: 0000000000000000 R14: 00000000014000c0 R15: ffffffff868bab20
  __do_kmalloc mm/slab.c:3700 [inline]
  __kmalloc+0x25/0x760 mm/slab.c:3714
  kmalloc include/linux/slab.h:517 [inline]
  relay_create_buf kernel/relay.c:172 [inline]
  relay_open_buf.part.10+0xc8/0x9b0 kernel/relay.c:449
  relay_open_buf kernel/relay.c:446 [inline]
  relay_open+0x57a/0xa40 kernel/relay.c:596
  do_blk_trace_setup+0x4a4/0xcd0 kernel/trace/blktrace.c:544
  __blk_trace_setup+0xbe/0x150 kernel/trace/blktrace.c:589
  blk_trace_ioctl+0x206/0x2e0 kernel/trace/blktrace.c:728
  blkdev_ioctl+0x1845/0x1e00 block/ioctl.c:587
  block_ioctl+0xde/0x120 fs/block_dev.c:1860
  vfs_ioctl fs/ioctl.c:46 [inline]
  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
  SYSC_ioctl fs/ioctl.c:701 [inline]
  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
  do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x443e79
RSP: 002b:00007ffe0625e398 EFLAGS: 00000202 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443e79
RDX: 0000000020beaf68 RSI: 00000000c0481273 RDI: 0000000000000003
RBP: 00000000006ce018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000401b20
R13: 0000000000401bb0 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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