From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Weijie Yang , Konrad Rzeszutek Wilk , Seth Jennings , Dan Streetman , Minchan Kim , Bob Liu , Andrew Morton , Linus Torvalds Subject: [PATCH 3.10 01/24] mm: frontswap: invalidate expired data on a dup-store failure Date: Sun, 14 Dec 2014 12:20:21 -0800 Message-Id: <20141214201800.664383585@linuxfoundation.org> In-Reply-To: <20141214201800.613573495@linuxfoundation.org> References: <20141214201800.613573495@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weijie Yang commit fb993fa1a2f669215fa03a09eed7848f2663e336 upstream. If a frontswap dup-store failed, it should invalidate the expired page in the backend, or it could trigger some data corruption issue. Such as: 1. use zswap as the frontswap backend with writeback feature 2. store a swap page(version_1) to entry A, success 3. dup-store a newer page(version_2) to the same entry A, fail 4. use __swap_writepage() write version_2 page to swapfile, success 5. zswap do shrink, writeback version_1 page to swapfile 6. version_2 page is overwrited by version_1, data corrupt. This patch fixes this issue by invalidating expired data immediately when meet a dup-store failure. Signed-off-by: Weijie Yang Cc: Konrad Rzeszutek Wilk Cc: Seth Jennings Cc: Dan Streetman Cc: Minchan Kim Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/frontswap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) the (older) page from frontswap */ inc_frontswap_failed_stores(); - if (dup) + if (dup) { __frontswap_clear(sis, offset); + frontswap_ops->invalidate_page(type, offset); + } } if (frontswap_writethrough_enabled) /* report failure so swap also writes to swap device */