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author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-01-15 16:54:37 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-15 17:56:32 -0800 |
commit | b20ce5e03b936be077463015661dcf52be274e5b (patch) | |
tree | 1004a054c0263a471ef79a7cd84fea904a71b655 /mm/page_idle.c | |
parent | e90309c9f7722db4ff5bce3b9e6e04d1460f2553 (diff) | |
download | linux-stable-b20ce5e03b936be077463015661dcf52be274e5b.tar.gz linux-stable-b20ce5e03b936be077463015661dcf52be274e5b.tar.bz2 linux-stable-b20ce5e03b936be077463015661dcf52be274e5b.zip |
mm: prepare page_referenced() and page_idle to new THP refcounting
Both page_referenced() and page_idle_clear_pte_refs_one() assume that
THP can only be mapped with PMD, so there's no reason to look on PTEs
for PageTransHuge() pages. That's no true anymore: THP can be mapped
with PTEs too.
The patch removes PageTransHuge() test from the functions and opencode
page table check.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_idle.c')
-rw-r--r-- | mm/page_idle.c | 65 |
1 files changed, 56 insertions, 9 deletions
diff --git a/mm/page_idle.c b/mm/page_idle.c index 1c245d9027e3..2c553ba969f8 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -56,23 +56,70 @@ static int page_idle_clear_pte_refs_one(struct page *page, { struct mm_struct *mm = vma->vm_mm; spinlock_t *ptl; + pgd_t *pgd; + pud_t *pud; pmd_t *pmd; pte_t *pte; bool referenced = false; - if (unlikely(PageTransHuge(page))) { - pmd = page_check_address_pmd(page, mm, addr, &ptl); - if (pmd) { - referenced = pmdp_clear_young_notify(vma, addr, pmd); + pgd = pgd_offset(mm, addr); + if (!pgd_present(*pgd)) + return SWAP_AGAIN; + pud = pud_offset(pgd, addr); + if (!pud_present(*pud)) + return SWAP_AGAIN; + pmd = pmd_offset(pud, addr); + + if (pmd_trans_huge(*pmd)) { + ptl = pmd_lock(mm, pmd); + if (!pmd_present(*pmd)) + goto unlock_pmd; + if (unlikely(!pmd_trans_huge(*pmd))) { spin_unlock(ptl); + goto map_pte; } + + if (pmd_page(*pmd) != page) + goto unlock_pmd; + + referenced = pmdp_clear_young_notify(vma, addr, pmd); + spin_unlock(ptl); + goto found; +unlock_pmd: + spin_unlock(ptl); + return SWAP_AGAIN; } else { - pte = page_check_address(page, mm, addr, &ptl, 0); - if (pte) { - referenced = ptep_clear_young_notify(vma, addr, pte); - pte_unmap_unlock(pte, ptl); - } + pmd_t pmde = *pmd; + + barrier(); + if (!pmd_present(pmde) || pmd_trans_huge(pmde)) + return SWAP_AGAIN; + + } +map_pte: + pte = pte_offset_map(pmd, addr); + if (!pte_present(*pte)) { + pte_unmap(pte); + return SWAP_AGAIN; } + + ptl = pte_lockptr(mm, pmd); + spin_lock(ptl); + + if (!pte_present(*pte)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + /* THP can be referenced by any subpage */ + if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) { + pte_unmap_unlock(pte, ptl); + return SWAP_AGAIN; + } + + referenced = ptep_clear_young_notify(vma, addr, pte); + pte_unmap_unlock(pte, ptl); +found: if (referenced) { clear_page_idle(page); /* |