openeuler inclusion
category: feature
bugzilla: https://portrait.gitee.com/openeuler/open-source-summer/issues/I56LAR
CVE: NA

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/proc/meminfo is the main way for user to know the physical memory
usage, but it cannot know every operation of allocating physical
pages. Some kernel modules can call alloc_pages to get physical
pages directly, which part of physical memory will not be counted
by /proc/meminfo.

In order to trace the specific process of physical page allocation
and release, one solution is to use ebpf to trace the calls of
__alloc_pages and __free_pages, a better solution is to insert
a new modules into kernel and register tracepoint handlers to
obtain the physical page allocation information. So i also export
the relative tracepoint symbols so that kernel module can use them.

Physical pages allocation may be a time-consuming operation, so i
added a new tracepoint named mm_page_alloc_enter at the entrance of
__alloc_pages. Before that, a tracepoint has been added in the
kernel at the end of the page allocation operation. The tracepoints
can be used to calculate the time consumption of the allocation
operation.
Signed-off-by: Gong Yuchen <gyc8787@163.com>