Revert "RDMA/rxe: Create duplicate mapping tables for FMRs"

Revert "RDMA/rxe: Create duplicate mapping tables for FMRs"

Below 2 commits will be reverted:
 commit 8ff5f5d9d8cf ("RDMA/rxe: Prevent double freeing rxe_map_set()")
 commit 647bf13ce944 ("RDMA/rxe: Create duplicate mapping tables for FMRs")

The community has a few bug reports which pointed this commit at last.
Some proposals are raised up in the meantime but all of them have no
follow-up operation.

The previous commit led the map_set of FMR to be not available any more if
the MR is registered again after invalidating. Although the mentioned
patch try to fix a potential race in building/accessing the same table
for fast memory regions, it broke rtrs etc ULPs. Since the latter could
be worse, revert this patch.

With previous commit, it's observed that a same MR in rnbd server will
trigger below code path:
 -> rxe_mr_init_fast()
 |-> alloc map_set() # map_set is uninitialized
 |...-> rxe_map_mr_sg() # build the map_set
     |-> rxe_mr_set_page()
 |...-> rxe_reg_fast_mr() # mr->state change to VALID from FREE that means
                          # we can access host memory(such rxe_mr_copy)
 |...-> rxe_invalidate_mr() # mr->state change to FREE from VALID
 |...-> rxe_reg_fast_mr() # mr->state change to VALID from FREE,
                          # but map_set was not built again
 |...-> rxe_mr_copy() # kernel crash due to access wild addresses
                      # that lookup from the map_set

The backtraces are not always identical.
[1st]----------
  RIP: 0010:lookup_iova+0x66/0xa0 [rdma_rxe]
  Code: 00 00 00 48 d3 ee 89 32 c3 4c 8b 18 49 8b 3b 48 8b 47 08 48 39 c6 72 38 48 29 c6 45 31 d2 b8 01 00 00 00 48 63 c8 48 c1 e1 04 <48> 8b 4c 0f 08 48 39 f1 77 21 83 c0 01 48 29 ce 3d 00 01 00 00 75
  RSP: 0018:ffffb7ff80063bf0 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffff9b9949d86800 RCX: 0000000000000000
  RDX: ffffb7ff80063c00 RSI: 0000000049f6b378 RDI: 002818da00000004
  RBP: 0000000000000120 R08: ffffb7ff80063c08 R09: ffffb7ff80063c04
  R10: 0000000000000002 R11: ffff9b9916f7eef8 R12: ffff9b99488a0038
  R13: ffff9b99488a0038 R14: ffff9b9914fb346a R15: ffff9b990ab27000
  FS:  0000000000000000(0000) GS:ffff9b997dc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007efc33a98ed0 CR3: 0000000014f32004 CR4: 00000000001706f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <TASK>
   rxe_mr_copy.part.0+0x6f/0x140 [rdma_rxe]
   rxe_responder+0x12ee/0x1b60 [rdma_rxe]
   ? rxe_icrc_check+0x7e/0x100 [rdma_rxe]
   ? rxe_rcv+0x1d0/0x780 [rdma_rxe]
   ? rxe_icrc_hdr.isra.0+0xf6/0x160 [rdma_rxe]
   rxe_do_task+0x67/0xb0 [rdma_rxe]
   rxe_xmit_packet+0xc7/0x210 [rdma_rxe]
   rxe_requester+0x680/0xee0 [rdma_rxe]
   ? update_load_avg+0x5f/0x690
   ? update_load_avg+0x5f/0x690
   ? rtrs_clt_recv_done+0x1b/0x30 [rtrs_client]

[2nd]----------
  RIP: 0010:rxe_mr_copy.part.0+0xa8/0x140 [rdma_rxe]
  Code: 00 00 49 c1 e7 04 48 8b 00 4c 8d 2c d0 48 8b 44 24 10 4d 03 7d 00 85 ed 7f 10 eb 6c 89 54 24 0c 49 83 c7 10 31 c0 85 ed 7e 5e <49> 8b 3f 8b 14 24 4c 89 f6 48 01 c7 85 d2 74 06 48 89 fe 4c 89 f7
  RSP: 0018:ffffae3580063bf8 EFLAGS: 00010202
  RAX: 0000000000018978 RBX: ffff9d7ef7a03600 RCX: 0000000000000008
  RDX: 000000000000007c RSI: 000000000000007c RDI: ffff9d7ef7a03600
  RBP: 0000000000000120 R08: ffffae3580063c08 R09: ffffae3580063c04
  R10: ffff9d7efece0038 R11: ffff9d7ec4b1db00 R12: ffff9d7efece0038
  R13: ffff9d7ef4098260 R14: ffff9d7f11e23c6a R15: 4c79500065708144
  FS:  0000000000000000(0000) GS:ffff9d7f3dc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007fce47276c60 CR3: 0000000003f66004 CR4: 00000000001706f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <TASK>
   rxe_responder+0x12ee/0x1b60 [rdma_rxe]
   ? rxe_icrc_check+0x7e/0x100 [rdma_rxe]
   ? rxe_rcv+0x1d0/0x780 [rdma_rxe]
   ? rxe_icrc_hdr.isra.0+0xf6/0x160 [rdma_rxe]
   rxe_do_task+0x67/0xb0 [rdma_rxe]
   rxe_xmit_packet+0xc7/0x210 [rdma_rxe]
   rxe_requester+0x680/0xee0 [rdma_rxe]
   ? update_load_avg+0x5f/0x690
   ? update_load_avg+0x5f/0x690
   ? rtrs_clt_recv_done+0x1b/0x30 [rtrs_client]
   rxe_do_task+0x67/0xb0 [rdma_rxe]
   tasklet_action_common.constprop.0+0x92/0xc0
   __do_softirq+0xe1/0x2d8
   run_ksoftirqd+0x21/0x30
   smpboot_thread_fn+0x183/0x220
   ? sort_range+0x20/0x20
   kthread+0xe2/0x110
   ? kthread_complete_and_exit+0x20/0x20
   ret_from_fork+0x22/0x30

Link: https://lore.kernel.org/r/1658805386-2-1-git-send-email-lizhijian@fujitsu.com
Link: https://lore.kernel.org/all/20220210073655.42281-1-guoqing.jiang@linux.dev/T/
Link: https://www.spinics.net/lists/linux-rdma/msg110836.html
Link: https://lore.kernel.org/lkml/94a5ea93-b8bb-3a01-9497-e2021f29598a@linux.dev/t/
Tested-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Reviewed-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>