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SubjectRe: [PATCH 1/9] migrate: add migrate_entry_wait_huge()
On Thu 21-02-13 14:41:40, Naoya Horiguchi wrote:
[...]
> diff --git v3.8.orig/mm/migrate.c v3.8/mm/migrate.c
> index 2fd8b4a..7d84f4c 100644
> --- v3.8.orig/mm/migrate.c
> +++ v3.8/mm/migrate.c
> @@ -236,6 +236,30 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
> pte_unmap_unlock(ptep, ptl);
> }
>
> +void migration_entry_wait_huge(struct mm_struct *mm, pmd_t *pmd,
> + unsigned long address)
> +{
> + spinlock_t *ptl = pte_lockptr(mm, pmd);
> + pte_t pte;
> + swp_entry_t entry;
> + struct page *page;
> +
> + spin_lock(ptl);
> + pte = huge_ptep_get((pte_t *)pmd);
> + if (!is_hugetlb_entry_migration(pte))
> + goto out;
> + entry = pte_to_swp_entry(pte);
> + page = migration_entry_to_page(entry);
> + if (!get_page_unless_zero(page))
> + goto out;
> + spin_unlock(ptl);
> + wait_on_page_locked(page);
> + put_page(page);
> + return;
> +out:
> + spin_unlock(ptl);
> +}

This duplicates a lot of code from migration_entry_wait. Can we just
teach the generic one to be HugePage aware instead?
All it takes is just opencoding pte_offset_map_lock and calling
huge_ptep_get ofr HugePage and pte_offset_map otherwise.
--
Michal Hocko
SUSE Labs


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