hulk inclusion
category: feature
bugzilla: 48159
CVE: N/A

We can use the checkpoint and restore in userspace(criu) method to
dump and restore tasks when updating the kernel.
Currently, criu needs dump all memory data of tasks to files.
When the memory size is very large(larger than 1G),
the cost time of the dumping data will be very long(more than 1 min).

By pin the memory data of tasks and collect the corresponding
physical pages mapping info in checkpoint process,
we can remap the physical pages to restore tasks after
upgrading the kernel. This pin memory method can
restore the task data within one second.

The pin memory area info is saved in the reserved memblock,
which can keep usable in the kernel update process.

The pin memory driver provides the following ioctl command for criu:
1) SET_PIN_MEM_AREA:
Set pin memory area, which can be remap to the restore task.
2) CLEAR_PIN_MEM_AREA:
Clear the pin memory area info,
which enable user reset the pin data.
3) REMAP_PIN_MEM_AREA:
Remap the pages of the pin memory to the restore task.
Signed-off-by: NJingxian He <hejingxian@huawei.com>
Reviewed-by: NWenliang He <hewenliang4@huawei.com>
Reviewed-by: NJing Xiangfeng <jingxiangfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>