Public bug reported:

[Impact]
On failing to migrate a page, soft_offline_huge_page() performs the necessary 
update to the hugepage ref-count.

But when !hugepage_migration_supported() , unmap_and_move_hugepage()
also decrements the page ref-count for the hugepage. The combined
behaviour leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite

[Testing]
Run the mce-test/cases/function/hwpoison/run_hugepage_overcommit.sh and you 
should see softlock up if hugepage migration support is not enabled.

[Fix]
upstream commit:
30809f559a0d mm/migrate: fix refcount handling when 
!hugepage_migration_supported()

[Regression Potential]

** Affects: linux (Ubuntu)
     Importance: High
     Assignee: Manoj Iyer (manjo)
         Status: Incomplete


** Tags: qdf2400

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https://bugs.launchpad.net/bugs/1696165

Title:
  [SRU][Zesty] fix soft lockup on overcommited hugepages

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