Re: Regression from 3.4.9 to 3.4.16 "stable" kernel

Mark Lord
2012-10-29T14:22:57Z

On 12-10-29 02:46 AM, Willy Tarreau wrote:
> On Mon, Oct 29, 2012 at 12:03:55AM -0400, Mark Lord wrote:
>> My server here runs the 3.4.xx series of "stable" kernels.
>> Until today, it was running 3.4.9.
>> Today I tried to upgrade it to 3.4.16.
>> It hangs in setup.c.
>>
>> I've isolated the fault down to this specific change
>> that was made between 3.4.9 and 3.4.16.
>> Reverting this change allows the system to boot/run normally again.
>>
>>
>> --- linux-3.4.9/arch/x86/kernel/setup.c 2012-08-15 11:17:17.000000000 -0400
>> +++ linux-3.4.16/arch/x86/kernel/setup.c 2012-10-28 13:36:33.000000000 -0400
>> @@ -927,8 +927,21 @@
>>
>> #ifdef CONFIG_X86_64
>> if (max_pfn > max_low_pfn) {
>> - max_pfn_mapped = init_memory_mapping(1UL<<32,
>> - max_pfn<<PAGE_SHIFT);
>> + int i;
>> + for (i = 0; i < e820.nr_map; i++) {
>> + struct e820entry *ei = &e820.map[i];
>> +
>> + if (ei->addr + ei->size <= 1UL << 32)
>> + continue;
>> +
>> + if (ei->type == E820_RESERVED)
>> + continue;
>> +
>> + max_pfn_mapped = init_memory_mapping(
>> + ei->addr < 1UL << 32 ? 1UL << 32 : ei->addr,
>> + ei->addr + ei->size);
>> + }
>> +
>> /* can we preseve max_low_pfn ?*/
>> max_low_pfn = max_pfn;
>> }
>
> For the record, it is this commit introduced in 3.4.16 :
>
> commit efd5fa0c1a1d1b46846ea6e8d1a783d0d8a6a721
> Author: Jacob Shin <jacob.shin@amd.com>
> Date: Thu Oct 20 16:15:26 2011 -0500
>
> x86: Exclude E820_RESERVED regions and memory holes above 4 GB from direct mapping.
>
> commit 1bbbbe779aabe1f0768c2bf8f8c0a5583679b54a upstream.
>
> On systems with very large memory (1 TB in our case), BIOS may report a
> reserved region or a hole in the E820 map, even above the 4 GB range. Exclude
> these from the direct mapping.
>
> [ hpa: this should be done not just for > 4 GB but for everything above the legacy
> region (1 MB), at the very least. That, however, turns out to require significant
> restructuring. That work is well underway, but is not suitable for rc/stable. ]
>
> Signed-off-by: Jacob Shin <jacob.shin@amd.com>
> Link: http://lkml.kernel.org/r/1319145326-13902-1-git-send-email-jacob.shin@amd.com
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> Willy

Thanks, Willy.

I've also now downloaded linux-3.7.0-rc3, and it boots/runs without need for patching.
So there's a fix somewhere in between that perhaps could also get backported to -stable.

-ml