Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755224AbaKRVlN (ORCPT ); Tue, 18 Nov 2014 16:41:13 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36741 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754178AbaKRVlM (ORCPT ); Tue, 18 Nov 2014 16:41:12 -0500 Date: Tue, 18 Nov 2014 13:41:10 -0800 From: Andrew Morton To: Weijie Yang Cc: konrad.wilk@oracle.com, "'Seth Jennings'" , "'Dan Streetman'" , "'Minchan Kim'" , "'Bob Liu'" , xfishcoder@gmail.com, "'Weijie Yang'" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure Message-Id: <20141118134110.d5e17eec0ff90ff8c957fffd@linux-foundation.org> In-Reply-To: <000001d0030d$0505aaa0$0f10ffe0$%yang@samsung.com> References: <000001d0030d$0505aaa0$0f10ffe0$%yang@samsung.com> X-Mailer: Sylpheed 3.4.0beta7 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 18 Nov 2014 16:51:36 +0800 Weijie Yang wrote: > 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. > > ... > > --- 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 */ I tagged this for backporting into -stable kernels. Please shout at me if you think that was inappropriate. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/