[CRIU] [PATCH 00/12] Introduce custom per-task service fds placement

[Kirill Tkhai]

Currently, service fds are bounded to rlimit(RLIMIT_NOFILE).
This brings problems with memory usage, because service fds
forces kernel to allocate big files_struct for every task,
and the container consumes much more memory, than it used
before dump. In some situations this even may lead to restore
fail because of enough memory absence in cgroup or on node.

This patchset reworks service fds placement, and places
the service fds in custom place for every task in dependence
of task's biggest fd used on dump. This reduces kernel-allocated
files_struct in significant way, and make container use less
memory.

The patchset consists of two parts. Patches [1-4/12] reworks
ctl tty crutch we used before, and makes ctl tty to restore
in generic file engine way. This change is good enough by its
own, and it has to be made separately earlier, but now is
the time to stop delaying, and to remove all the crutch, because
this is need for the second part.

The second part of patchset places service fds in dependence
of task's used fds as described in start of topic. See patches
[5-12/12] for details of that.

Patch [12/12] actually makes service fds "per-task placed".

https://travis-ci.org/tkhai/criu/builds/321817890
---

Kirill Tkhai (12):
      files: Close ctl tty via generic engine
      files: Move prepare_ctl_tty() to criu/tty.c
      files: Move CTL_TTY_OFF fixup to generic file engine
      files: Kill unused CTL_TTY_OFF leftovers
      files: Rename service_fd_rlim_cur to service_fd_base_cur
      files: Count inh_fd_max
      files: Pass pstree_item argument to clone_service_fd()
      files: Close old service fd in clone_service_fd()
      files: Do setup_newborn_fds() later
      files: Refactor clone_service_fd()
      files: Prepare clone_service_fd() for overlaping ranges.
      files: Make tasks set their own service_fd_base


 criu/cr-restore.c        |   14 +++--
 criu/files.c             |   45 +++-------------
 criu/include/files.h     |    3 +
 criu/include/servicefd.h |    4 -
 criu/include/tty.h       |    2 -
 criu/include/util.h      |    2 +
 criu/tty.c               |  127 +++++++++++++++++++++++++++++++++++++++++++---
 criu/util.c              |  101 ++++++++++++++++++++++++++-----------
 images/fdinfo.proto      |    1 
 9 files changed, 214 insertions(+), 85 deletions(-)

--
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>