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Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c29
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);
}