diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/ksm.c | 49 |
1 files changed, 39 insertions, 10 deletions
@@ -39,6 +39,7 @@ #include <linux/freezer.h> #include <linux/oom.h> #include <linux/numa.h> +#include <linux/pagewalk.h> #include <asm/tlbflush.h> #include "internal.h" @@ -419,6 +420,39 @@ static inline bool ksm_test_exit(struct mm_struct *mm) return atomic_read(&mm->mm_users) == 0; } +static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long next, + struct mm_walk *walk) +{ + struct page *page = NULL; + spinlock_t *ptl; + pte_t *pte; + int ret; + + if (pmd_leaf(*pmd) || !pmd_present(*pmd)) + return 0; + + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + if (pte_present(*pte)) { + page = vm_normal_page(walk->vma, addr, *pte); + } else if (!pte_none(*pte)) { + swp_entry_t entry = pte_to_swp_entry(*pte); + + /* + * As KSM pages remain KSM pages until freed, no need to wait + * here for migration to end. + */ + if (is_migration_entry(entry)) + page = pfn_swap_entry_to_page(entry); + } + ret = page && PageKsm(page); + pte_unmap_unlock(pte, ptl); + return ret; +} + +static const struct mm_walk_ops break_ksm_ops = { + .pmd_entry = break_ksm_pmd_entry, +}; + /* * We use break_ksm to break COW on a ksm page by triggering unsharing, * such that the ksm page will get replaced by an exclusive anonymous page. @@ -434,21 +468,16 @@ static inline bool ksm_test_exit(struct mm_struct *mm) */ static int break_ksm(struct vm_area_struct *vma, unsigned long addr) { - struct page *page; vm_fault_t ret = 0; do { - bool ksm_page = false; + int ksm_page; cond_resched(); - page = follow_page(vma, addr, - FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE); - if (IS_ERR_OR_NULL(page)) - break; - if (PageKsm(page)) - ksm_page = true; - put_page(page); - + ksm_page = walk_page_range_vma(vma, addr, addr + 1, + &break_ksm_ops, NULL); + if (WARN_ON_ONCE(ksm_page < 0)) + return ksm_page; if (!ksm_page) return 0; ret = handle_mm_fault(vma, addr, |