Re: [RFC v2][PATCH 1/9] kernel based checkpoint-restart

From: Oren Laadan
Date: Thu Aug 21 2008 - 01:17:28 EST



Subject line should have been 's/PATCH 1/PATCH 0/' ...

I left cr_debug() in for now to provide more info than pr_debug();
eventually that will be changed back to pr_debug()

In the mini-conference we considered doing CR in a kernel module,
but decided against because we needed a system call. It is still
possible to put the bulk of the code in a module. This is useful,
besides reducing debug time (recompile, unload, reload), to reduce
the kernel memory footprint. Also, an administrator can load/unload
the module to enable/disable this feature. Any thoughts ?

Oren.

Oren Laadan wrote:

These patches implement checkpoint-restart [CR v2]. This version adds
save and restore of open files state (regular files and directories)
which makes it more usable. Other changes address the feedback given
for the previous version. It is also refactored (along Dave's posting)
for easier reviewing.

Todo:
- Add support for x86-64 and improve ABI
- Refine or change syscall interface
- Extend to handle (multiple) tasks in a container
- Security (without CAPS_SYS_ADMIN files restore may fail)

Changelog:

[2008-Aug-20] v2:
- Added dump and restore of open files (regular and directories);
see the changes in the test program (ckpt.c)
- Added basic handling of shared objects, and use 'parent tag'
- Added documentation
- Improved ABI, add 64bit padding for image data
- Improved locking when saving/restoring memory
- Added UTS information to header (release, version, machine)
- Cleanup extraction of filename from a file pointer
- Refactor to allow easier reviewing
- Remove requirement for CAPS_SYS_ADMIN until we come up with a
security policy (this means that file restore may fail)
- Other cleanup in response to comments for v1

[2008-Jul-29] v1:
- Initial version: support a single task with address space of only
private anonymous or file-mapped VMAs; syscalls ignore pid/crid
argument and act on current process.


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