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
Status in linux package in Ubuntu:
Incomplete
Bug description:
[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]
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