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mm: prepare page_referenced() and page_idle to new THP refcounting

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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>
This commit is contained in:
Kirill A. Shutemov
2016-01-15 16:54:37 -08:00
committed by Linus Torvalds
parent e90309c9f7
commit b20ce5e03b
6 changed files with 188 additions and 115 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
mm/rmap.c
View File

@@ -814,58 +814,105 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
spinlock_t *ptl;
int referenced = 0;
struct page_referenced_arg *pra = arg;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
if (unlikely(PageTransHuge(page))) {
pmd_t *pmd;
/*
* rmap might return false positives; we must filter
* these out using page_check_address_pmd().
*/
pmd = page_check_address_pmd(page, mm, address, &ptl);
if (!pmd)
if (unlikely(PageHuge(page))) {
/* when pud is not present, pte will be NULL */
pte = huge_pte_offset(mm, address);
if (!pte)
return SWAP_AGAIN;
if (vma->vm_flags & VM_LOCKED) {
ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
goto check_pte;
}
pgd = pgd_offset(mm, address);
if (!pgd_present(*pgd))
return SWAP_AGAIN;
pud = pud_offset(pgd, address);
if (!pud_present(*pud))
return SWAP_AGAIN;
pmd = pmd_offset(pud, address);
if (pmd_trans_huge(*pmd)) {
int ret = SWAP_AGAIN;
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;
if (vma->vm_flags & VM_LOCKED) {
pra->vm_flags |= VM_LOCKED;
return SWAP_FAIL; /* To break the loop */
ret = SWAP_FAIL; /* To break the loop */
goto unlock_pmd;
}
if (pmdp_clear_flush_young_notify(vma, address, pmd))
referenced++;
spin_unlock(ptl);
goto found;
unlock_pmd:
spin_unlock(ptl);
return ret;
} else {
pte_t *pte;
pmd_t pmde = *pmd;
/*
* rmap might return false positives; we must filter
* these out using page_check_address().
*/
pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
barrier();
if (!pmd_present(pmde) || pmd_trans_huge(pmde))
return SWAP_AGAIN;
if (vma->vm_flags & VM_LOCKED) {
pte_unmap_unlock(pte, ptl);
pra->vm_flags |= VM_LOCKED;
return SWAP_FAIL; /* To break the loop */
}
if (ptep_clear_flush_young_notify(vma, address, pte)) {
/*
* Don't treat a reference through a sequentially read
* mapping as such. If the page has been used in
* another mapping, we will catch it; if this other
* mapping is already gone, the unmap path will have
* set PG_referenced or activated the page.
*/
if (likely(!(vma->vm_flags & VM_SEQ_READ)))
referenced++;
}
pte_unmap_unlock(pte, ptl);
}
map_pte:
pte = pte_offset_map(pmd, address);
if (!pte_present(*pte)) {
pte_unmap(pte);
return SWAP_AGAIN;
}
ptl = pte_lockptr(mm, pmd);
check_pte:
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;
}
if (vma->vm_flags & VM_LOCKED) {
pte_unmap_unlock(pte, ptl);
pra->vm_flags |= VM_LOCKED;
return SWAP_FAIL; /* To break the loop */
}
if (ptep_clear_flush_young_notify(vma, address, pte)) {
/*
* Don't treat a reference through a sequentially read
* mapping as such. If the page has been used in
* another mapping, we will catch it; if this other
* mapping is already gone, the unmap path will have
* set PG_referenced or activated the page.
*/
if (likely(!(vma->vm_flags & VM_SEQ_READ)))
referenced++;
}
pte_unmap_unlock(pte, ptl);
found:
if (referenced)
clear_page_idle(page);
if (test_and_clear_page_young(page))
@@ -912,7 +959,7 @@ int page_referenced(struct page *page,
int ret;
int we_locked = 0;
struct page_referenced_arg pra = {
.mapcount = page_mapcount(page),
.mapcount = total_mapcount(page),
.memcg = memcg,
};
struct rmap_walk_control rwc = {