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#### Try and find the CPT number being passed on the stack to lnet_initiate_peer_discovery()
crash> bt
PID: 8874   TASK: ffff881ff97d3f40  CPU: 7   COMMAND: "mdt_rdpg02_014"
 #0 [ffff881e4a6b3660] machine_kexec at ffffffff8105d77b
 #1 [ffff881e4a6b36c0] __crash_kexec at ffffffff81108742
 #2 [ffff881e4a6b3790] panic at ffffffff816a863f
 #3 [ffff881e4a6b3810] __warn at ffffffff8108ae7a
 #4 [ffff881e4a6b3850] warn_slowpath_fmt at ffffffff8108aedf
 #5 [ffff881e4a6b38b8] __list_add at ffffffff8134405c
 #6 [ffff881e4a6b38e0] lnet_initiate_peer_discovery at ffffffffc0b07bc7 [lnet]
 #7 [ffff881e4a6b3918] lnet_handle_find_routed_path at ffffffffc0b0b90d [lnet]
 #8 [ffff881e4a6b3998] lnet_select_pathway at ffffffffc0b0c2c0 [lnet]
 #9 [ffff881e4a6b3a98] lnet_send at ffffffffc0b0d115 [lnet]
#10 [ffff881e4a6b3ab8] LNetPut at ffffffffc0b0d56c [lnet]
#11 [ffff881e4a6b3b18] ptl_send_buf at ffffffffc0e00ff6 [ptlrpc]
#12 [ffff881e4a6b3bd0] ptlrpc_send_reply at ffffffffc0e043ab [ptlrpc]
#13 [ffff881e4a6b3c48] target_send_reply_msg at ffffffffc0dc335e [ptlrpc]
#14 [ffff881e4a6b3c68] target_send_reply at ffffffffc0dcd7de [ptlrpc]
#15 [ffff881e4a6b3cc0] tgt_request_handle at ffffffffc0e73d11 [ptlrpc]
#16 [ffff881e4a6b3d50] ptlrpc_server_handle_request at ffffffffc0e16c6b [ptlrpc]
#17 [ffff881e4a6b3df0] ptlrpc_main at ffffffffc0e1a63a [ptlrpc]
#18 [ffff881e4a6b3ec8] kthread at ffffffff810b4031
#19 [ffff881e4a6b3f50] ret_from_fork at ffffffff816c155d

crash> disas  lnet_handle_find_routed_path

  2    0xffffffffc0b0b740 <+0>:»····nopl   0x0(%rax,%rax,1)
  3    0xffffffffc0b0b745 <+5>:»····push   %rbp
  4    0xffffffffc0b0b746 <+6>:»····mov    %rsp,%rbp
  5    0xffffffffc0b0b749 <+9>:»····push   %r15
  6    0xffffffffc0b0b74b <+11>:»···mov    %rdi,%r15 <--- RDI is used to pass the first argument gets stored in r15
  7    0xffffffffc0b0b74e <+14>:»···push   %r14
  8    0xffffffffc0b0b750 <+16>:»···push   %r13
  9    0xffffffffc0b0b752 <+18>:»···push   %r12
 10    0xffffffffc0b0b754 <+20>:»···push   %rbx

2001 static int
2002 lnet_handle_find_routed_path(struct lnet_send_data *sd,
2003 »·······»·······»·······     lnet_nid_t dst_nid,
2004 »·······»·······»·······     struct lnet_peer_ni **gw_lpni,
2005 »·······»·······»·······     struct lnet_peer **gw_peer)

2076 »·······sd->sd_msg->msg_src_nid_param = sd->sd_src_nid;
2077 »·······rc = lnet_initiate_peer_discovery(gwni, sd->sd_msg, sd->sd_rtr_nid,
2078 »·······»·······»·······»·······»·······  sd->sd_cpt);


crash> disas lnet_initiate_peer_discovery
  1 Dump of assembler code for function lnet_initiate_peer_discovery:
  2    0xffffffffc0b07aa0 <+0>:»····nopl   0x0(%rax,%rax,1)
  3    0xffffffffc0b07aa5 <+5>:»····push   %rbp
  4    0xffffffffc0b07aa6 <+6>:»····mov    %rsp,%rbp
  5    0xffffffffc0b07aa9 <+9>:»····push   %r15
  6    0xffffffffc0b07aab <+11>:»···push   %r14
  7    0xffffffffc0b07aad <+13>:»···push   %r13
  8    0xffffffffc0b07aaf <+15>:»···push   %r12
  9    0xffffffffc0b07ab1 <+17>:»···push   %rbx

# r15 is being saved on the stack by lnet_initiate_peer_discovery. So now we look there

crash> bt -f
 #6 [ffff881e4a6b38e0] lnet_initiate_peer_discovery at ffffffffc0b07bc7 [lnet]
    ffff881e4a6b38e8: ffff881f4be670c0 (%rbx) ffff881f4be67000 (%r12) 
    ffff881e4a6b38f8: ffff881f8d3b2400 (%r13) ffff881f8d33bb40 (%r14) 
    ffff881e4a6b3908: ffff881e4a6b39f8 (%r15) ffff881e4a6b3990 (%rbp)
    ffff881e4a6b3918: ffffffffc0b0b90d (return address in caller)
crash> lnet_send_data ffff881e4a6b39f8
struct lnet_send_data {
  sd_best_ni = 0xffff881f8d3b2200, 
  sd_best_lpni = 0xffff881f9575f600, 
  sd_final_dst_lpni = 0xffff881f9575f600, 
  sd_peer = 0xffff881ff7f4cd00, 
  sd_gw_peer = 0x0, 
  sd_gw_lpni = 0x0, 
  sd_peer_net = 0x0, 
  sd_msg = 0xffff880e4cb6f400, 
  sd_dst_nid = 3659191877107818, 
  sd_src_nid = 1407546850803763, 
  sd_rtr_nid = 18446744073709551615, 
  sd_cpt = 2, 
  sd_md_cpt = 0, 
  sd_send_case = 25
}