On Wed 2018-09-19 15:37:15, Chen Yu wrote:
> From: Zhimin Gu <kookoo...@intel.com>
>
> 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:
>
> 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.
>
> Acked-by: Pavel Machek <pa...@ucw.cz>
Thanks.
I think this is nasty enough to add Cc: stable.
Pavel
--
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