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-rw-r--r--mm/rmap.c21
1 files changed, 0 insertions, 21 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 9827409..89770bd 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);
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