Re: [Bug 11388] New: 2.6.27-rc3 warns about MTRR range; only 3 of 16gb of memory is usable

[Yinghai Lu]

On Wed, Aug 20, 2008 at 6:04 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> (switched to email.  Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
>
> On Wed, 20 Aug 2008 17:38:59 -0700 (PDT)
> bugme-daemon@xxxxxxxxxxxxxxxxxxx wrote:
>
>> http://bugzilla.kernel.org/show_bug.cgi?id=11388
>>
>>            Summary: 2.6.27-rc3 warns about MTRR range; only 3 of 16gb of
>>                     memory is usable
>>            Product: Memory Management
>>            Version: 2.5
>>      KernelVersion: 2.6.27-rc3
>>           Platform: All
>>         OS/Version: Linux
>>               Tree: Mainline
>>             Status: NEW
>>           Severity: normal
>>           Priority: P1
>>          Component: MTTR
>>         AssignedTo: akpm@xxxxxxxx
>>         ReportedBy: j_kernel@xxxxxxxxxxx
>>
>>
>> Latest working kernel version: 2.4.24.2 (possibly later)
>> Earliest failing kernel version: 2.6.27-rc3-21328-ga7f5aaf (from netdev-2.6)
>> Distribution: Gentoo
>> Hardware Environment: 2x Intel X5482
>> Software Environment:
>> Problem Description:
>>
>> [    0.000000] WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing
>> 13056MB of RAM.
>> [    0.000000] ------------[ cut here ]------------
>> [    0.000000] WARNING: at arch/x86/kernel/cpu/mtrr/main.c:1561
>> mtrr_trim_uncached_memory+0x508/0x550()
>> [    0.000000] Modules linked in:
>> [    0.000000] Pid: 0, comm: swapper Not tainted 2.6.27-rc3-21328-ga7f5aaf #8
>> [    0.000000]
>> [    0.000000] Call Trace:
>> [    0.000000]  [<ffffffff80234c3e>] warn_on_slowpath+0x51/0x77
>> [    0.000000]  [<ffffffff8023570a>] printk+0x4e/0x56
>> [    0.000000]  [<ffffffff803add02>] sort+0xfa/0x18c
>> [    0.000000]  [<ffffffff808283d3>] cmp_range+0x0/0x6
>> [    0.000000]  [<ffffffff80828a47>] mtrr_trim_uncached_memory+0x508/0x550
>> [    0.000000]  [<ffffffff802178e1>] post_set+0x20/0x3d
>> [    0.000000]  [<ffffffff80824f99>] setup_arch+0x39d/0x6be
>> [    0.000000]  [<ffffffff8081e962>] start_kernel+0x74/0x341
>> [    0.000000]  [<ffffffff8081e394>] x86_64_start_kernel+0xe3/0xe7
>> [    0.000000]
>> [    0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---
>>
>>
>> Steps to reproduce:
>>
>> This warning isn't present under 2.6.24.2 and the full range of physical memory
>> is usable.
>
> Looks like a post-2.6.26 regression caused by
> 12031a624af7816ec7660b82be648aa3703b4ebe.
reg00: base=0xd0000000 (3328MB), size=196864MB: uncachable, count=1
reg01: base=0xe0000000 (3584MB), size=197120MB: uncachable, count=1
reg02: base=0x00000000 (   0MB), size=212992MB: write-back, count=1
reg03: base=0x400000000 (16384MB), size=197120MB: write-back, count=1
reg04: base=0x420000000 (16896MB), size=196864MB: write-back, count=1

the size mtrr looks crazy.

YH
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