3.16.63-rc1 review patch. If anyone has any objections, please let me know.
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From: Zhimin Gu kookoo.gu@intel.com
commit cc55f7537db6af371e9c1c6a71161ee40f918824 upstream.
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@intel.com Acked-by: Pavel Machek pavel@ucw.cz Signed-off-by: Chen Yu yu.c.chen@intel.com Acked-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/x86/kernel/setup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1234,7 +1234,7 @@ void __init setup_arch(char **cmdline_p) kvm_guest_init();
e820_reserve_resources(); - e820_mark_nosave_regions(max_low_pfn); + e820_mark_nosave_regions(max_pfn);
x86_init.resources.reserve_resources();