From: Zhimin Gu <kookoo.gu@xxxxxxxxx>
[ Upstream commit cc55f7537db6af371e9c1c6a71161ee40f918824 ]
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:
[ 612.800453] Disabling lock debugging due to kernel taint
[ 612.805786] mce: [Hardware Error]: CPU 0: Machine Check Exception: 5 Bank 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 SOCKET 0 APIC 0 microcode 24
[ 612.839581] mce: [Hardware Error]: Run the above through 'mcelog --ascii'
[ 612.846394] mce: [Hardware Error]: Machine check: Processor context corrupt
[ 612.853380] Kernel panic - not syncing: Fatal machine check
[ 612.858978] Kernel Offset: 0x18000000 from 0xc1000000 (relocation range: 0xc0000000-0xf7ffdfff)
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
memory, which triggered the MCE:
e820 memory mapping:
[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009d7ff] usable
[ 0.000000] BIOS-e820: [mem 0x000000000009d800-0x000000000009ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000d160cfff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000d160d000-0x00000000d1613fff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000d1614000-0x00000000d1a44fff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000d1a45000-0x00000000d1ecffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000d1ed0000-0x00000000d7eeafff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000d7eeb000-0x00000000d7ffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000d8000000-0x00000000d875ffff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000d8760000-0x00000000d87fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000d8800000-0x00000000d8fadfff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000d8fae000-0x00000000d8ffffff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x00000000d9000000-0x00000000da71bfff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000da71c000-0x00000000da7fffff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000da800000-0x00000000dbb8bfff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000dbb8c000-0x00000000dbffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000dd000000-0x00000000df1fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000f8000000-0x00000000fbffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed00000-0x00000000fed03fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000041edfffff] usable
Fix this problem by changing pfn limit from max_low_pfn to max_pfn.
This fix does not impact 64bit system because on 64bit max_low_pfn
is the same as max_pfn.
Signed-off-by: Zhimin Gu <kookoo.gu@xxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: All applicable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kernel/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b4866badb235a..90ecc108bc8a5 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1251,7 +1251,7 @@ void __init setup_arch(char **cmdline_p)
x86_init.hyper.guest_late_init();
e820__reserve_resources();
- e820__register_nosave_regions(max_low_pfn);
+ e820__register_nosave_regions(max_pfn);
x86_init.resources.reserve_resources();
--
2.20.1
