diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 43 |
1 files changed, 27 insertions, 16 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 471eb04066ff..c2082ab4fc93 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1552,23 +1552,33 @@ int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, return 0; } +/* + * This function returns whether a given @page is mapped onto the @address + * in the virtual space of @mm. + * + * When it's true, this function returns *pmd with holding the page table lock + * and passing it back to the caller via @ptl. + * If it's false, returns NULL without holding the page table lock. + */ pmd_t *page_check_address_pmd(struct page *page, struct mm_struct *mm, unsigned long address, - enum page_check_address_pmd_flag flag) + enum page_check_address_pmd_flag flag, + spinlock_t **ptl) { - pmd_t *pmd, *ret = NULL; + pmd_t *pmd; if (address & ~HPAGE_PMD_MASK) - goto out; + return NULL; pmd = mm_find_pmd(mm, address); if (!pmd) - goto out; + return NULL; + *ptl = pmd_lock(mm, pmd); if (pmd_none(*pmd)) - goto out; + goto unlock; if (pmd_page(*pmd) != page) - goto out; + goto unlock; /* * split_vma() may create temporary aliased mappings. There is * no risk as long as all huge pmd are found and have their @@ -1578,14 +1588,15 @@ pmd_t *page_check_address_pmd(struct page *page, */ if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG && pmd_trans_splitting(*pmd)) - goto out; + goto unlock; if (pmd_trans_huge(*pmd)) { VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG && !pmd_trans_splitting(*pmd)); - ret = pmd; + return pmd; } -out: - return ret; +unlock: + spin_unlock(*ptl); + return NULL; } static int __split_huge_page_splitting(struct page *page, @@ -1593,6 +1604,7 @@ static int __split_huge_page_splitting(struct page *page, unsigned long address) { struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; pmd_t *pmd; int ret = 0; /* For mmu_notifiers */ @@ -1600,9 +1612,8 @@ static int __split_huge_page_splitting(struct page *page, const unsigned long mmun_end = address + HPAGE_PMD_SIZE; mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); - spin_lock(&mm->page_table_lock); pmd = page_check_address_pmd(page, mm, address, - PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG); + PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl); if (pmd) { /* * We can't temporarily set the pmd to null in order @@ -1613,8 +1624,8 @@ static int __split_huge_page_splitting(struct page *page, */ pmdp_splitting_flush(vma, address, pmd); ret = 1; + spin_unlock(ptl); } - spin_unlock(&mm->page_table_lock); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); return ret; @@ -1745,14 +1756,14 @@ static int __split_huge_page_map(struct page *page, unsigned long address) { struct mm_struct *mm = vma->vm_mm; + spinlock_t *ptl; pmd_t *pmd, _pmd; int ret = 0, i; pgtable_t pgtable; unsigned long haddr; - spin_lock(&mm->page_table_lock); pmd = page_check_address_pmd(page, mm, address, - PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG); + PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl); if (pmd) { pgtable = pgtable_trans_huge_withdraw(mm, pmd); pmd_populate(mm, &_pmd, pgtable); @@ -1807,8 +1818,8 @@ static int __split_huge_page_map(struct page *page, pmdp_invalidate(vma, address, pmd); pmd_populate(mm, pmd, pgtable); ret = 1; + spin_unlock(ptl); } - spin_unlock(&mm->page_table_lock); return ret; } |