Re: Bug: 2.6.24-smp: Eeek! page_mapcount(page) went negative! (-1)

[Hugh Dickins]

On Wed, 6 Feb 2008, kerndev@xxxxxxxxxxxxxxx wrote:
> 
> Before digging into this myself (don't really have enought time),
> I thought I'd submit it here...

Thanks for the report.

> Feb  6 09:09:47 sc-software kernel: Eeek! page_mapcount(page) went negative!

These very often turn out the be due to bad RAM or some such:
worth running memtest86+ overnight when you can, though its
success wouldn't be conclusive.

> (-1)
> Feb  6 09:09:47 sc-software kernel:   page pfn = 12b1b1
> Feb  6 09:09:47 sc-software kernel:   page->flags = 80080014
> Feb  6 09:09:47 sc-software kernel:   page->count = 0

That's a free page which shouldn't have appeared in the pagetable.
It could be that there's a bit error somewhere in that pfn of 12b1b1.

> Feb  6 09:09:47 sc-software kernel:   page->mapping = 00000000
> Feb  6 09:09:47 sc-software kernel:   vma->vm_ops = 0x0
> Feb  6 09:09:47 sc-software kernel: ------------[ cut here ]------------
> Feb  6 09:09:47 sc-software kernel: kernel BUG at mm/rmap.c:631!
> Feb  6 09:09:47 sc-software kernel: invalid opcode: 0000 [#2] PREEMPT SMP
> Feb  6 09:09:47 sc-software kernel: Modules linked in: shpchp pci_hotplug
> ohci1394 ieee1394
> Feb  6 09:09:47 sc-software kernel:
> Feb  6 09:09:47 sc-software kernel: Pid: 3710, comm: X Tainted: G      D

But that [#2] and that D taint both say there was already a problem
before this: anything showing in the log for that?

Hugh
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