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Commit 6742d293 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm: adjust FOLL_SPLIT for new refcounting 



We need to prepare kernel to allow transhuge pages to be mapped with
ptes too.  We need to handle FOLL_SPLIT in follow_page_pte().

Also we use split_huge_page() directly instead of split_huge_page_pmd().
split_huge_page_pmd() will gone.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: default avatarSasha Levin <sasha.levin@oracle.com>
Tested-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarJerome Marchand <jmarchan@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f25fe20

mm/gup.c

+49 −18
Original line number Diff line number Diff line
@@ -116,6 +116,19 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, 
		}

	}



	if (flags & FOLL_SPLIT && PageTransCompound(page)) {

		int ret;

		get_page(page);

		pte_unmap_unlock(ptep, ptl);

		lock_page(page);

		ret = split_huge_page(page);

		unlock_page(page);

		put_page(page);

		if (ret)

			return ERR_PTR(ret);

		goto retry;

	}



	if (flags & FOLL_GET)

		get_page_foll(page);

	if (flags & FOLL_TOUCH) {
@@ -220,27 +233,45 @@ struct page *follow_page_mask(struct vm_area_struct *vma, 
	}

	if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))

		return no_page_table(vma, flags);

	if (pmd_trans_huge(*pmd)) {

		if (flags & FOLL_SPLIT) {

			split_huge_page_pmd(vma, address, pmd);

	if (likely(!pmd_trans_huge(*pmd)))

		return follow_page_pte(vma, address, pmd, flags);

		}



	ptl = pmd_lock(mm, pmd);

		if (likely(pmd_trans_huge(*pmd))) {

	if (unlikely(!pmd_trans_huge(*pmd))) {

		spin_unlock(ptl);

		return follow_page_pte(vma, address, pmd, flags);

	}



	if (unlikely(pmd_trans_splitting(*pmd))) {

		spin_unlock(ptl);

		wait_split_huge_page(vma->anon_vma, pmd);

		return follow_page_pte(vma, address, pmd, flags);

	}



	if (flags & FOLL_SPLIT) {

		int ret;

		page = pmd_page(*pmd);

		if (is_huge_zero_page(page)) {

			spin_unlock(ptl);

			ret = 0;

			split_huge_page_pmd(vma, address, pmd);

		} else {

				page = follow_trans_huge_pmd(vma, address,

							     pmd, flags);

			get_page(page);

			spin_unlock(ptl);

				*page_mask = HPAGE_PMD_NR - 1;

				return page;

			lock_page(page);

			ret = split_huge_page(page);

			unlock_page(page);

			put_page(page);

		}

		} else

			spin_unlock(ptl);



		return ret ? ERR_PTR(ret) :

			follow_page_pte(vma, address, pmd, flags);

	}

	return follow_page_pte(vma, address, pmd, flags);



	page = follow_trans_huge_pmd(vma, address, pmd, flags);

	spin_unlock(ptl);

	*page_mask = HPAGE_PMD_NR - 1;

	return page;

}



static int get_gate_page(struct mm_struct *mm, unsigned long address,