[Devel] [PATCH RFC VZ10 0/2] Improve RPC kill-tasks mechanism

[Vladimir Riabchun]

There is a hack for stopping containers with RPC connections,
but is has several flaws.

They are described in the second commit and in the task
https://virtuozzo.atlassian.net/browse/VSTOR-126316

Suggested approach - atomic (with respect to the set of
network namespaces) iteration over nets and RPC kill
in each.

One questionable point - RCU protection of rpc_kill_net_fn.
If there are many namespaces in general, the loop may take
a while and cause soft lockup. So:
1. Maybe race between rpc_kill request and sunrpc unload is
   impossible? In this case all this locking is not needed.
2. Maybe there is an easier way of providing a callback from
   module?

Tested by a CT with nested network namespace.

Current vzctl per-PID approach:
[  590.261534] kill-tasks: by task (vzctl:14066) in net:[4026533581]
[  591.308176] CT: acded8b8-6a7a-494e-a4f1-a58767276b6f: stopped

With new machine.slice/CTID/ve.rpc_kill interface:
[  663.055995] kill-tasks: by task (bash:4084) in net:[4026533581]
[  663.056371] kill-tasks: by task (bash:4084) in net:[4026533987]

Vladimir Riabchun (2):
  ve/sunrpc: Refactor {rpc, write}_kill_tasks
  ve/sunrpc: Implement a per-ve sunrpc killer

 include/linux/sunrpc/clnt.h |  2 ++
 include/linux/ve.h          |  4 ++++
 kernel/ve/ve.c              | 44 +++++++++++++++++++++++++++++++++++++
 net/sunrpc/clnt.c           | 31 ++++++++++++++------------
 net/sunrpc/sunrpc_syms.c    |  3 +++
 5 files changed, 70 insertions(+), 14 deletions(-)

-- 
2.47.1