On Thu, Jun 14, 2012 at 2:34 PM, Sasha Levin [off-list ref] wrote:

On Thu, 2012-06-14 at 13:56 -0700, Yinghai Lu wrote:

quoted

On Thu, Jun 14, 2012 at 2:50 AM, Sasha Levin [off-list ref] wrote:

quoted

On Thu, 2012-06-14 at 12:20 +0900, Tejun Heo wrote:

quoted

On Wed, Jun 13, 2012 at 11:38:55PM +0200, Sasha Levin wrote:

quoted

Hi all,

I'm seeing the following when booting a KVM guest with 65gb of RAM, on latest linux-next.

Note that it happens with numa=off.

[    0.000000] BUG: unable to handle kernel paging request at ffff88102febd948
[    0.000000] IP: [<ffffffff836a6f37>] __next_free_mem_range+0x9b/0x155

Can you map it back to the source line please?

mm/memblock.c:583

                       phys_addr_t r_start = ri ? r[-1].base + r[-1].size : 0;
 97:   85 d2                   test   %edx,%edx
 99:   74 08                   je     a3 <__next_free_mem_range+0xa3>
 9b:   49 8b 48 f0             mov    -0x10(%r8),%rcx
 9f:   49 03 48 e8             add    -0x18(%r8),%rcx

It's the deref on 9b (r8=ffff88102febd958).

that reserved.region is allocated by memblock.

can you boot with "memblock=debug debug ignore_loglevel" and post
whole boot log?

Attached below. I've also noticed it doesn't always happen, but
increasing the vcpu count (to something around 254) makes it happen
almost every time.

...
[    0.000000] memblock: reserved array is doubled to 512 at
[0x102febc080-0x102febf07f]
[    0.000000]    memblock_free: [0x0000102febf080-0x0000102fec0880]
memblock_double_array+0x1b0/0x1e2
[    0.000000] memblock_reserve: [0x0000102febc080-0x0000102febf080]
memblock_double_array+0x1c5/0x1e2

the reserved regions get double two times to 512.
....

[    0.000000]    memblock_free: [0x0000102febc080-0x0000102febf080] memblock_free_reserved_regions+0x37/0x39
[    0.000000] BUG: unable to handle kernel paging request at ffff88102febd948
[    0.000000] IP: [<ffffffff836a5774>] __next_free_mem_range+0x9b/0x155
[    0.000000] PGD 4826063 PUD cf67a067 PMD cf7fa067 PTE 800000102febd160

that page table for them is

[    0.000000] kernel direct mapping tables up to 0x102fffffff @ [mem
0xc7e3e000-0xcfffffff]
[    0.000000] memblock_reserve: [0x000000c7e3e000-0x000000cf7fb000]
native_pagetable_reserve+0xc/0xe

only near by allocation is swiotlb.

[    0.000000] __ex_table already sorted, skipping sort
[    0.000000] memblock_reserve: [0x000000c3e3e000-0x000000c7e3e000]
__alloc_memory_core_early+0x5c/0x73
...
[    0.000000] memblock_reserve: [0x000000cfff8000-0x000000d0000000]
__alloc_memory_core_early+0x5c/0x73
[    0.000000] Checking aperture...

so the memblock allocation is ok...

can you please boot with "memtest" to see if there is any memory problem?

Thanks

Yinghai

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