From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f52.google.com (mail-qg0-f52.google.com [209.85.192.52]) by kanga.kvack.org (Postfix) with ESMTP id 433946B0038 for ; Tue, 18 Nov 2014 17:30:31 -0500 (EST) Received: by mail-qg0-f52.google.com with SMTP id a108so6243935qge.39 for ; Tue, 18 Nov 2014 14:30:31 -0800 (PST) Received: from relay.variantweb.net ([104.131.199.242]) by mx.google.com with ESMTP id g5si8428444qab.87.2014.11.18.14.29.39 for ; Tue, 18 Nov 2014 14:30:09 -0800 (PST) Received: from mail (unknown [10.42.10.20]) by relay.variantweb.net (Postfix) with ESMTP id 9778810138E for ; Tue, 18 Nov 2014 17:29:35 -0500 (EST) Date: Tue, 18 Nov 2014 16:29:36 -0600 From: Seth Jennings Subject: Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure Message-ID: <20141118222936.GB20945@cerebellum.variantweb.net> References: <000001d0030d$0505aaa0$0f10ffe0$%yang@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000001d0030d$0505aaa0$0f10ffe0$%yang@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Weijie Yang Cc: konrad.wilk@oracle.com, 'Andrew Morton' , 'Dan Streetman' , 'Minchan Kim' , 'Bob Liu' , xfishcoder@gmail.com, 'Weijie Yang' , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Nov 18, 2014 at 04:51:36PM +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. Good catch! > > This patch fixes this issue by invalidating expired data immediately > when meet a dup-store failure. > > Signed-off-by: Weijie Yang > --- > mm/frontswap.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/mm/frontswap.c b/mm/frontswap.c > index c30eec5..f2a3571 100644 > --- 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); Looking at __frontswap_invalidate_page(), should we do inc_frontswap_invalidates() too? If so, maybe we should just call __frontswap_invalidate_page(). Thanks, Seth > + } > } > if (frontswap_writethrough_enabled) > /* report failure so swap also writes to swap device */ > -- > 1.7.0.4 > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org