On Fri, Aug 09, 2013 at 01:21:36AM -0400, Naoya Horiguchi wrote:
> This patch extends check_range() to handle vma with VM_HUGETLB set.
> We will be able to migrate hugepage with migrate_pages(2) after
> applying the enablement patch which comes later in this series.
>
> Note that for larger hugepages (covered by pud entries, 1GB for
> x86_64 for example), we simply skip it now.
>
> Note that using pmd_huge/pud_huge assumes that hugepages are pointed to
> by pmd/pud. This is not true in some architectures implementing hugepage
> with other mechanisms like ia64, but it's OK because pmd_huge/pud_huge
> simply return 0 in such arch and page walker simply ignores such hugepages.
>
> ChangeLog v4:
> - refactored check_hugetlb_pmd_range for better readability
>
> ChangeLog v3:
> - revert introducing migrate_movable_pages
> - use isolate_huge_page
>
> ChangeLog v2:
> - remove unnecessary extern
> - fix page table lock in check_hugetlb_pmd_range
> - updated description and renamed patch title
>
> Signed-off-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
> Acked-by: Andi Kleen <a...@linux.intel.com>
> Reviewed-by: Wanpeng Li <liw...@linux.vnet.ibm.com>
> Acked-by: Hillf Danton <dhi...@gmail.com>
> ---
> mm/mempolicy.c | 42 +++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 37 insertions(+), 5 deletions(-)
>
> diff --git v3.11-rc3.orig/mm/mempolicy.c v3.11-rc3/mm/mempolicy.c
> index 7431001..d96afc1 100644
> --- v3.11-rc3.orig/mm/mempolicy.c
> +++ v3.11-rc3/mm/mempolicy.c
> @@ -512,6 +512,30 @@ static int check_pte_range(struct vm_area_struct *vma,
> pmd_t *pmd,
> return addr != end;
> }
>
> +static void check_hugetlb_pmd_range(struct vm_area_struct *vma, pmd_t *pmd,
> + const nodemask_t *nodes, unsigned long flags,
> + void *private)
> +{
> +#ifdef CONFIG_HUGETLB_PAGE
> + int nid;
> + struct page *page;
> +
> + spin_lock(&vma->vm_mm->page_table_lock);
> + page = pte_page(huge_ptep_get((pte_t *)pmd));
> + nid = page_to_nid(page);
> + if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
> + goto unlock;
> + /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
> + if (flags & (MPOL_MF_MOVE_ALL) ||
> + (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
> + isolate_huge_page(page, private);
> +unlock:
> + spin_unlock(&vma->vm_mm->page_table_lock);
> +#else
> + BUG();
> +#endif
> +}
> +
> static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud,
> unsigned long addr, unsigned long end,
> const nodemask_t *nodes, unsigned long flags,
> @@ -523,6 +547,11 @@ static inline int check_pmd_range(struct vm_area_struct
> *vma, pud_t *pud,
> pmd = pmd_offset(pud, addr);
> do {
> next = pmd_addr_end(addr, end);
> + if (pmd_huge(*pmd) && is_vm_hugetlb_page(vma)) {
> + check_hugetlb_pmd_range(vma, pmd, nodes,
> + flags, private);
> + continue;
> + }
> split_huge_page_pmd(vma, addr, pmd);
> if (pmd_none_or_trans_huge_or_clear_bad(pmd))
> continue;
If a hugepage is currently being migrated then a migration entry should
be in its place which is a type of swap entry. Will the pmd_huge check
still do the right thing if migration is already in progress?
> if (check_pmd_range(vma, pud, addr, next, nodes,
> @@ -635,9 +666,6 @@ check_range(struct mm_struct *mm, unsigned long start,
> unsigned long end,
> return ERR_PTR(-EFAULT);
> }
>
> - if (is_vm_hugetlb_page(vma))
> - goto next;
> -
> if (flags & MPOL_MF_LAZY) {
> change_prot_numa(vma, start, endvma);
> goto next;
> @@ -986,7 +1014,11 @@ static void migrate_page_add(struct page *page, struct
> list_head *pagelist,
>
> static struct page *new_node_page(struct page *page, unsigned long node, int
> **x)
> {
> - return alloc_pages_exact_node(node, GFP_HIGHUSER_MOVABLE, 0);
> + if (PageHuge(page))
> + return alloc_huge_page_node(page_hstate(compound_head(page)),
> + node);
> + else
> + return alloc_pages_exact_node(node, GFP_HIGHUSER_MOVABLE, 0);
> }
>
> /*
> @@ -1016,7 +1048,7 @@ static int migrate_to_node(struct mm_struct *mm, int
> source, int dest,
> err = migrate_pages(&pagelist, new_node_page, dest,
> MIGRATE_SYNC, MR_SYSCALL);
> if (err)
> - putback_lru_pages(&pagelist);
> + putback_movable_pages(&pagelist);
> }
>
> return err;
> --
> 1.8.3.1
>
--
Mel Gorman
SUSE Labs
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