From mboxrd@z Thu Jan 1 00:00:00 1970 From: joeyli Subject: Re: [RFC PATCH] PM / hibernate: make sure each resuming page is in current memory zones Date: Mon, 6 Jul 2015 16:37:39 +0800 Message-ID: <20150706083739.GA29021@linux-rxt1.site> References: <1435679668-13806-1-git-send-email-yu.c.chen@intel.com> <20150702061935.GA19010@linux-rxt1.site> <5594EFAA.1000905@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp.nue.novell.com ([195.135.221.5]:60112 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751454AbbGFIh4 (ORCPT ); Mon, 6 Jul 2015 04:37:56 -0400 Content-Disposition: inline In-Reply-To: <5594EFAA.1000905@intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: chenyu5 Cc: linux-pm@vger.kernel.org, rafael.j.wysocki@intel.com, rui.zhang@intel.com, len.brown@intel.com, aaron.lu@intel.com, ying.huang@intel.com Hi Chen Yu,=20 On Thu, Jul 02, 2015 at 04:00:42PM +0800, chenyu5 wrote: > Hi, Joey > thanks for your reply, >=20 > On 2015=E5=B9=B407=E6=9C=8802=E6=97=A5 14:19, joeyli wrote: > >Hi Chen Yu, > > > >On Tue, Jun 30, 2015 at 11:54:28PM +0800, Chen Yu wrote: > >>Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e820 re= served > >>regions") was reverted, because this patch makes resume from hibern= ation > >>on Lenovo x230 unreliable. But reverting may bring back the kernel > >>exception firstly reported in former patch. In general, there are t= hree > >>problems in current code when resuming from hibernation: > >> > >>1.Resuming page may also be in second kernel's e820 reserved region= =2E > >>BIOS-e820: [mem 0x0000000069d4f000-0x0000000069e12fff] reserved > >>this causes kernel exception described in Commit 84c91b7ae07c > >>("PM / hibernate: avoid unsafe pages in e820 reserved regions") > >> > >>2.If Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e8= 20 > >>reserved regions") is applied to fix problem 1, and if E820_RESERVE= D_KERN > >>regions causes some regions at e820 table not page aligned, > >>e820_mark_nosave_regions will misjudgment the non-page aligned spac= e to > >>be "hole" space and add to nosave regions, this causes resuming fai= led. > >>Refer to https://bugzilla.kernel.org/show_bug.cgi?id=3D96111 for de= tail. > >> > > > >Sorry for I am not fully understand why checking pfn_valid could avo= id > >the above 2. issue? > > > [Yu] According to e820_mark_nosave_regions, two kinds of e820 > regions will be regarded as nosave: > a.e820.map holes between each e820entry > b.e820entry with (!E820_RAM && !E820_RESERVED_KERN) > dmesg in > https://bugzilla.kernel.org/show_bug.cgi?id=3D96111 > shows that: >=20 > BIOS-e820: [mem 0x000000005baff000-0x00000000d684ffff] usable > reserve setup_data: [mem 0x000000009d3e0018-0x000000009d3f0057] usabl= e > PM: Registered nosave memory: [mem 0x9d3e0000-0x9d3e0fff] >=20 > e820 map was changed by situation a, but it should not be added to > nosave list, right? >=20 > and according to saveable_page, only pages in the zone will be saved: > if (page_zone(page_ !=3D zone) > return NULL; >=20 > The function of is_valid_orig_page in this patch treats setup_data as > valid page, so I think this workaround issue 2. >=20 >=20 > >Per my understood should waiting Yinghai Lu's patches for killing > >E820_RESERVED_KERN to avoid the aligned problem. > [Yu] yes, it is a graceful solution, but I don't see that in 4.1? And > we encountered problem 3 in our testing enviroment, so I wrote a patc= h > to deal with it first. > > > > > >Thanks a lot! > >Joey Lee > > Thanks for your explanation, then your patch makes sense to me. Please feel free to add tag: Reviewed-by: Lee, Chun-Yi Thanks a lot! Joey Lee