mm/hwpoison: add migrate_page_mc_extra()

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8K5CO



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During page migration, page is copied in kernel space. If the origin page
has UCE, there will lead to kernel panic.

In order to solve this problem, use machine check safe to catch this
error which can be achieved by using copy_mc_to_kernel to replace
copy_page. Signal SIGBUS will be send to user task if this UCE
is consumed by this situation to avoid kernel panic.

Add a new param to copy_huge_page to support mc. If mc is set
copy_mc_higepage will be called rather than copy_hugepage during
memory copy.

Since migrate_page_move_mapping() is done before page copy, rollback is
hard due to race condition. Do copy page at the start of function
migrate_page_mc_extra() to solve this problem.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>