Re: [memcg BUG] unable to handle kernel NULL pointer derefence at 00000000

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Tue, 21 Oct 2008 15:04:15 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:

> You mean this ?
> 
> 000881c8 <page_cgroup_zoneinfo>:
>    881c8:       55                      push   %ebp
>    881c9:       8b 50 04                mov    0x4(%eax),%edx
>    881cc:       8b 40 08                mov    0x8(%eax),%eax
>    881cf:       89 e5                   mov    %esp,%ebp
>    881d1:       5d                      pop    %ebp
>    881d2:       8b 00                   mov    (%eax),%eax
>    881d4:       c1 e8 1e                shr    $0x1e,%eax
>    881d7:       6b c0 58                imul   $0x58,%eax,%eax
>    881da:       03 42 48                add    0x48(%edx),%eax
>    881dd:       c3                      ret
> 
Yes. thank you. This is helpful. From this, page_cgroup->page pointer is NULL.
And page_zid() or some kicks it..

Then, it seems problem is in page_cgroup.c::page_cgroup_init() or
page_cgroup()->page is cleared..Hmm..

could you show /var/log/dmesg ?
It may includes following kinds of line

= (this is x86-64)
sizeof(struct page) = 96
Zone PFN ranges:
  DMA      0x00000000 -> 0x00001000
  DMA32    0x00001000 -> 0x00100000
  Normal   0x00100000 -> 0x00a40000
Movable zone start PFN for each node
early_node_map[4] active PFN ranges
    0: 0x00000000 -> 0x0000009e
    0: 0x00000100 -> 0x000bfee0
    0: 0x000bff00 -> 0x000bff80
    0: 0x00100000 -> 0x00a40000
On node 0 totalpages: 10485502
  DMA zone: 96 pages used for memmap
  DMA zone: 102 pages reserved
  DMA zone: 3800 pages, LIFO batch:0
  DMA32 zone: 24480 pages used for memmap
  DMA32 zone: 757696 pages, LIFO batch:31
  Normal zone: 227328 pages used for memmap
  Normal zone: 9472000 pages, LIFO batch:31
  Movable zone: 0 pages used for memmap
.....

Thanks,
-Kame

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