PROBLEM: memory corrupting bug, bisected to 6dda9d55

[Andrew Morton]

On Mon, 18 Oct 2010 12:33:31 +0100
Mel Gorman <mel at csn.ul.ie> wrote:

> A bit but I still don't know why it would cause corruption. Maybe this is still
> a caching issue but the difference in timing between list_add and list_add_tail
> is enough to hide the bug. It's also possible there are some registers
> ioremapped after the memmap array and reading them is causing some
> problem.
> 
> Andrew, what is the right thing to do here? We could flail around looking
> for explanations as to why the bug causes a user buffer corruption but never
> get an answer or do we go with this patch, preferably before 2.6.36 releases?

Well, you've spotted a bug so I'd say we fix it asap.

It's a bit of a shame that we lose the only known way of reproducing a
different bug, but presumably that will come back and bite someone else
one day, and we'll fix it then :(