Re: msync() oops in 2.6.7-rc2-bk1

[Andrew Morton]

"Miquel van Smoorenburg" <miquels@xxxxxxxxxx> wrote:
>
> I'm running a news server. The innd process uses mmap()s for several
> files and uses msync() to force synchronization to disk every so
> often. Suddenly, an msync() causes an oops (and innd SEGVs). This
> is after the box has been up and running for 3 days:
> 
> # uname -a
> Linux enterprise 2.6.7-rc2-bk1 #1 Mon May 31 15:03:52 CEST 2004 i686 GNU/Linux
> 
>  <1>Unable to handle kernel NULL pointer dereference at virtual address 00000000 printing eip:
> c0149120
> *pde = 00000000
> Oops: 0002 [#5]
> Modules linked in: e100 mii
> CPU:    0
> EIP:    0060:[<c0149120>]    Not tainted
> EFLAGS: 00010213   (2.6.7-rc2-bk1)
> EIP is at __set_page_dirty_buffers+0x20/0xb0
> eax: 00000000   ebx: f77a1e7c   ecx: c15706e0   edx: eba5a83c
> esi: 5ccfb000   edi: 00000000   ebp: 5d000000   esp: f44b5efc
> ds: 007b   es: 007b   ss: 0068
> Process innd (pid: 10936, threadinfo=f44b5000 task=d0eb2c70)
> Stack: f77a1de4 00000004 00000000 c4af23ec c013143e c15706e0 c013da1c 5ccfb000
>        c4af23f0 c013db0f c4af23ec f7101900 5ccfb000 00000001 5cc00000 ce8b25d0
>        00000000 5d000000 c013dbc3 ce8b25cc 5cc00000 5d000000 f7101900 00000001
> Call Trace:
>  [<c013143e>] set_page_dirty+0x3e/0x50
>  [<c013da1c>] filemap_sync_pte+0x5c/0x80
>  [<c013db0f>] filemap_sync_pte_range+0xcf/0xf0
>  [<c013dbc3>] filemap_sync+0x93/0x100
>  [<c013dc96>] msync_interval+0x66/0xf0
>  [<c013de37>] sys_msync+0x117/0x123
>  [<c0103c7b>] syscall_call+0x7/0xb
> 
> Code: 0f ba 28 01 8b 40 08 39 d0 75 f5 0f ba 29 04 19 c0 85 c0 75

You have a page which has PG_private set, but page->private is NULL.  And
the machine is non-SMP, non-preempt, yes?

I'd be wondering whether that machine has flipped a bit in page->flags,
frankly.  How old is it?

Was the mmap of a regular file or of a block device?
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