From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756305Ab3EFT5W (ORCPT ); Mon, 6 May 2013 15:57:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45633 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755573Ab3EFT5U (ORCPT ); Mon, 6 May 2013 15:57:20 -0400 From: Andrea Arcangeli To: qemu-devel@nongnu.org, linux-kernel@vger.kernel.org Cc: Isaku Yamahata , Juan Quintela , Orit Wasserman , Paolo Bonzini , Anthony Liguori , Rik van Riel , Mel Gorman , Hugh Dickins Subject: [PATCH 3/4] mm: swp_entry_swapcount Date: Mon, 6 May 2013 21:57:00 +0200 Message-Id: <1367870221-12676-4-git-send-email-aarcange@redhat.com> In-Reply-To: <1367870221-12676-1-git-send-email-aarcange@redhat.com> References: <1367870221-12676-1-git-send-email-aarcange@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Provide a new swapfile method for remap_anon_pages to verify the swap entry is mapped only in one vma before relocating the swap entry in a different virtual address. Otherwise if the swap entry is mapped in multiple vmas, when the page is swapped back in, it could get mapped in a non linear way in some anon_vma. Signed-off-by: Andrea Arcangeli --- include/linux/swap.h | 6 ++++++ mm/swapfile.c | 13 +++++++++++++ 2 files changed, 19 insertions(+) diff --git a/include/linux/swap.h b/include/linux/swap.h index 1701ce4..0ea2a56 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -389,6 +389,7 @@ extern unsigned int count_swap_pages(int, int); extern sector_t map_swap_page(struct page *, struct block_device **); extern sector_t swapdev_block(int, pgoff_t); extern int page_swapcount(struct page *); +extern int swp_entry_swapcount(swp_entry_t entry); extern struct swap_info_struct *page_swap_info(struct page *); extern int reuse_swap_page(struct page *); extern int try_to_free_swap(struct page *); @@ -489,6 +490,11 @@ static inline int page_swapcount(struct page *page) return 0; } +static inline int swp_entry_swapcount(swp_entry_t entry) +{ + return 0; +} + #define reuse_swap_page(page) (page_mapcount(page) == 1) static inline int try_to_free_swap(struct page *page) diff --git a/mm/swapfile.c b/mm/swapfile.c index d417efd..2772382 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -671,6 +671,19 @@ int page_swapcount(struct page *page) return count; } +int swp_entry_swapcount(swp_entry_t entry) +{ + int count = 0; + struct swap_info_struct *p; + + p = swap_info_get(entry); + if (p) { + count = swap_count(p->swap_map[swp_offset(entry)]); + spin_unlock(&p->lock); + } + return count; +} + /* * We can write to an anon page without COW if there are no other references * to it. And as a side-effect, free up its swap: because the old content