vm_ops is now initialized in ib_uverbs_mmap() with the recent rdma mmap
API changes. Earlier it was done in rdma_umap_priv_init() which would not
be called unless a driver called rdma_user_mmap_io() in its mmap.

i40iw does not use the rdma_user_mmap_io API but sets the vma's
vm_private_data to a driver object. This now conflicts with the vm_op
rdma_umap_close as priv pointer points to the i40iw driver object instead
of the private data setup by core when rdma_user_mmap_io is called.  This
leads to a crash in rdma_umap_close with a mmap put being called when it
should not have.

Remove the redundant setting of the vma private_data in i40iw as it is not
used. Also move i40iw over to use the rdma_user_mmap_io API. This gives
the extra protection of having the mappings zapped when the context is
detsroyed.

  BUG: unable to handle page fault for address: 0000000100000001
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP PTI
  CPU: 6 PID: 9528 Comm: rping Kdump: loaded Not tainted 5.5.0-rc4+ #117
  Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./Q87M-D2H, BIOS F7 01/17/2014
  RIP: 0010:rdma_user_mmap_entry_put+0xa/0x30 [ib_core]
  RSP: 0018:ffffb340c04c7c38 EFLAGS: 00010202
  RAX: 00000000ffffffff RBX: ffff9308e7be2a00 RCX: 000000000000cec0
  RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000100000001
  RBP: ffff9308dc7641f0 R08: 0000000000000001 R09: 0000000000000000
  R10: 0000000000000001 R11: ffffffff8d4414d8 R12: ffff93075182c780
  R13: 0000000000000001 R14: ffff93075182d2a8 R15: ffff9308e2ddc840
  FS:  0000000000000000(0000) GS:ffff9308fdc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000100000001 CR3: 00000002e0412004 CR4: 00000000001606e0
  Call Trace:
   rdma_umap_close+0x40/0x90 [ib_uverbs]
   remove_vma+0x43/0x80
   exit_mmap+0xfd/0x1b0
   mmput+0x6e/0x130
   do_exit+0x290/0xcc0
   ? get_signal+0x152/0xc40
   do_group_exit+0x46/0xc0
   get_signal+0x1bd/0xc40
   ? prepare_to_wait_event+0x97/0x190
   do_signal+0x36/0x630
   ? remove_wait_queue+0x60/0x60
   ? __audit_syscall_exit+0x1d9/0x290
   ? rcu_read_lock_sched_held+0x52/0x90
   ? kfree+0x21c/0x2e0
   exit_to_usermode_loop+0x4f/0xc3
   do_syscall_64+0x1ed/0x270
   entry_SYSCALL_64_after_hwframe+0x49/0xbe
  RIP: 0033:0x7fae715a81fd
  Code: Bad RIP value.
  RSP: 002b:00007fae6e163cb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
  RAX: fffffffffffffe00 RBX: 00007fae6e163d30 RCX: 00007fae715a81fd
  RDX: 0000000000000010 RSI: 00007fae6e163cf0 RDI: 0000000000000003
  RBP: 00000000013413a0 R08: 00007fae68000000 R09: 0000000000000017
  R10: 0000000000000001 R11: 0000000000000293 R12: 00007fae680008c0
  R13: 00007fae6e163cf0 R14: 00007fae717c9804 R15: 00007fae6e163ed0
  CR2: 0000000100000001
  ---[ end trace b33d58d3a06782cb ]---
  RIP: 0010:rdma_user_mmap_entry_put+0xa/0x30 [ib_core]

Fixes: b86deba9 ("RDMA/core: Move core content from ib_uverbs to ib_core")
Link: https://lore.kernel.org/r/20200107162223.1745-1-shiraz.saleem@intel.comSigned-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>