As for the buddy system, much of docs mention the physical address of
the first page frame of a block should be a multiple of the group
size. For example, the initial address of a 16-page-frame block should
be 16-page aligned. I happened to encounted an issue that the physical
addresss pf the block is not 4-page aligned(0x36c9000) while the order
of the block is 2. I want to know what out of buddy algorithm depend
on this feature? My problem seems to happen in
schedule()->context_switch() call, but so far I didn't figure out the
root cause.