[LU-20163] ptlrpc should unregister procfs/debugfs entries early

• Type: Bug
• Resolution: Unresolved
• Priority: Medium
• Severity: 3
• Assignee: WC Triage
• Reporter: Alex Zhuravlev

Description

ptlrpc should unregister procfs/debugfs entries early so they don't try to access internal structures being released:

[  568.904972] LustreError: 173799:0:(lproc_ptlrpc.c:575:ptlrpc_lprocfs_nrs_seq_show()) ASSERTION( pol_idx < num_pols ) failed: 
[  568.905174] LustreError: 173799:0:(lproc_ptlrpc.c:575:ptlrpc_lprocfs_nrs_seq_show()) LBUG
[  568.905250] CPU: 1 PID: 173799 Comm: lctl Tainted: G        W  O      -------- -  - 4.18.0 #1
[  568.905362] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014
[  568.905425] Call Trace:
[  568.906211]  dump_stack+0x6e/0xa0
[  568.906300]  lbug_with_loc.cold.4+0x5/0x4e [libcfs]
[  568.906381]  ptlrpc_lprocfs_nrs_seq_show+0x3c7/0x840 [ptlrpc]
[  568.906533]  ? rcu_read_lock_held_common+0x9/0x30
[  568.906578]  ? rcu_read_lock_sched_held+0xe/0x60
[  568.906618]  ? __kmalloc+0x218/0x2e0
[  568.906700]  seq_read+0x14e/0x3e0
[  568.906738]  full_proxy_read+0x4b/0x70
[  568.906773]  vfs_read+0xa1/0x150
[  568.906807]  ksys_read+0x3d/0xa0
[  568.906840]  do_syscall_64+0x4b/0x1d0
[  568.906872]  entry_SYSCALL_64_after_hwframe+0x4e/0xc3
[  568.906916] RIP: 0033:0x7f3e6c9d59b2