diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 29 |
1 files changed, 4 insertions, 25 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 378de234c12..89770bd25f3 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -539,27 +539,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) goto out_unmap; } - /* - * Don't pull an anonymous page out from under get_user_pages. - * GUP carefully breaks COW and raises page count (while holding - * page_table_lock, as we have here) to make sure that the page - * cannot be freed. If we unmap that page here, a user write - * access to the virtual address will bring back the page, but - * its raised count will (ironically) be taken to mean it's not - * an exclusive swap page, do_wp_page will replace it by a copy - * page, and the user never get to see the data GUP was holding - * the original page for. - * - * This test is also useful for when swapoff (unuse_process) has - * to drop page lock: its reference to the page stops existing - * ptes from being unmapped, so swapoff can make progress. - */ - if (PageSwapCache(page) && - page_count(page) != page_mapcount(page) + 2) { - ret = SWAP_FAIL; - goto out_unmap; - } - /* Nuke the page table entry. */ flush_cache_page(vma, address, page_to_pfn(page)); pteval = ptep_clear_flush(vma, address, pte); @@ -586,7 +565,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) dec_mm_counter(mm, anon_rss); } - inc_mm_counter(mm, rss); + dec_mm_counter(mm, rss); page_remove_rmap(page); page_cache_release(page); @@ -626,7 +605,7 @@ static void try_to_unmap_cluster(unsigned long cursor, pgd_t *pgd; pud_t *pud; pmd_t *pmd; - pte_t *pte; + pte_t *pte, *original_pte; pte_t pteval; struct page *page; unsigned long address; @@ -658,7 +637,7 @@ static void try_to_unmap_cluster(unsigned long cursor, if (!pmd_present(*pmd)) goto out_unlock; - for (pte = pte_offset_map(pmd, address); + for (original_pte = pte = pte_offset_map(pmd, address); address < end; pte++, address += PAGE_SIZE) { if (!pte_present(*pte)) @@ -694,7 +673,7 @@ static void try_to_unmap_cluster(unsigned long cursor, (*mapcount)--; } - pte_unmap(pte); + pte_unmap(original_pte); out_unlock: spin_unlock(&mm->page_table_lock); } |