Hello,

syzbot hit the following crash on upstream commit
ce380619fab99036f5e745c7a865b21c59f005f6 (Tue Mar 6 04:31:14 2018 +0000)
Merge tag 'please-pull-ia64_misc' of  
git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

So far this crash happened 52 times on upstream.
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+a38b0e9f694c379ca7ce@syzkaller.appspotmail.com
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audit: type=1400 audit(1520367364.281:6): avc:  denied  { map } for   
pid=4138 comm="bash" path="/bin/bash" dev="sda1" ino=1457  
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
audit: type=1400 audit(1520367370.605:7): avc:  denied  { map } for   
pid=4152 comm="syzkaller100190" path="/root/syzkaller100190328" 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: 4152 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: 4152 Comm: syzkaller100190 Not tainted 4.16.0-rc4+ #343
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+0x194/0x24d 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+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:kmalloc_slab+0x5d/0x70 mm/slab_common.c:1012
RSP: 0018:ffff8801bf76f970 EFLAGS: 00010246
RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: ffffffff819733cb
RDX: ffffffff8423372f RSI: 0000000000000000 RDI: 000000003efef4b4
RBP: ffff8801bf76f970 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff88613380 R11: 0000000000000000 R12: 000000003efef4b4
R13: 0000000020000080 R14: 00000000014200c0 R15: ffff8801bf76fa68
  __do_kmalloc mm/slab.c:3700 [inline]
  __kmalloc_track_caller+0x21/0x760 mm/slab.c:3720
  memdup_user+0x2c/0x90 mm/util.c:160
  ucma_set_option+0x11f/0x4d0 drivers/infiniband/core/ucma.c:1297
  ucma_write+0x2d6/0x3d0 drivers/infiniband/core/ucma.c:1627
  __vfs_write+0xef/0x970 fs/read_write.c:480
  vfs_write+0x189/0x510 fs/read_write.c:544
  SYSC_write fs/read_write.c:589 [inline]
  SyS_write+0xef/0x220 fs/read_write.c:581
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43fe69
RSP: 002b:00007ffe099a6388 EFLAGS: 00000217 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fe69
RDX: 000000000000006b RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000217 R12: 0000000000401790
R13: 0000000000401820 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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