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Date:   Mon, 27 Aug 2018 11:48:11 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Gu Zhimin <kookoo.gu@intel.com>
Cc:     "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Yu Chen <yu.c.chen@intel.com>,
        x86@kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] x86, hibernate: Fix nosave_regions setup for
 hibernation
Message-ID: <20180827094811.GA31905@amd>
References: <cover.1535361949.git.kookoo.gu@intel.com>
 <73b18a8b87a465fc442366cccf5542307c4f1ae9.1535361949.git.kookoo.gu@intel.com>
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On Mon 2018-08-27 17:42:05, Gu Zhimin wrote:
> From: Zhimin Gu <kookoo.gu@intel.com>
>=20
> On 32bit systems, nosave_regions(non RAM areas) located between
> max_low_pfn and max_pfn are not excluded from hibernation snapshot
> currently, which may result in a machine check exception when
> trying to access these unsafe regions during hibernation:
>=20
> [  612.800453] Disabling lock debugging due to kernel taint
> [  612.805786] mce: [Hardware Error]: CPU 0: Machine Check Exception: 5 B=
ank 6: fe00000000801136
> [  612.814344] mce: [Hardware Error]: RIP !INEXACT! 60:<00000000d90be566>=
 {swsusp_save+0x436/0x560}
> [  612.823167] mce: [Hardware Error]: TSC 1f5939fe276 ADDR dd000000 MISC =
30e0000086
> [  612.830677] mce: [Hardware Error]: PROCESSOR 0:306c3 TIME 1529487426 S=
OCKET 0 APIC 0 microcode 24
> [  612.839581] mce: [Hardware Error]: Run the above through 'mcelog --asc=
ii'
> [  612.846394] mce: [Hardware Error]: Machine check: Processor context co=
rrupt
> [  612.853380] Kernel panic - not syncing: Fatal machine check
> [  612.858978] Kernel Offset: 0x18000000 from 0xc1000000 (relocation rang=
e: 0xc0000000-0xf7ffdfff)
>=20
> This is because on 32bit systems, pages above max_low_pfn are regarded
> as high memeory, and accessing unsafe pages might cause expected MCE.
> On the problematic 32bit system, there are reserved memory above low memo=
ry,
> which triggered the MCE:
>=20
> e820 memory mapping:
> [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009d7ff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x000000000009d800-0x000000000009ffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000d160cfff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000d160d000-0x00000000d1613fff] ACP=
I NVS
> [    0.000000] BIOS-e820: [mem 0x00000000d1614000-0x00000000d1a44fff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000d1a45000-0x00000000d1ecffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000d1ed0000-0x00000000d7eeafff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000d7eeb000-0x00000000d7ffffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000d8000000-0x00000000d875ffff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000d8760000-0x00000000d87fffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000d8800000-0x00000000d8fadfff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000d8fae000-0x00000000d8ffffff] ACP=
I data
> [    0.000000] BIOS-e820: [mem 0x00000000d9000000-0x00000000da71bfff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000da71c000-0x00000000da7fffff] ACP=
I NVS
> [    0.000000] BIOS-e820: [mem 0x00000000da800000-0x00000000dbb8bfff] usa=
ble
> [    0.000000] BIOS-e820: [mem 0x00000000dbb8c000-0x00000000dbffffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000dd000000-0x00000000df1fffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000f8000000-0x00000000fbffffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000fed00000-0x00000000fed03fff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] res=
erved
> [    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000041edfffff] usa=
ble
>=20
> Fix this problem by changing pfn limit from max_low_pfn to max_pfn.
> This issue should also exist on 64bits systems, if there are reserved
> regions above 4GB.
>=20
> Acked-by: Chen Yu <yu.c.chen@intel.com>
> Signed-off-by: Zhimin Gu <kookoo.gu@intel.com>

Acked-by: Pavel Machek <pavel@ucw.cz>


--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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