Re: kernel bug: mmap, XIP, page faults, multiple threads

[Hugh Dickins <hughd@google.com>]

On Thu, 26 Jan 2012, Louis Alex Eisner wrote:
> 
>    I hope I'm sending this to the right people, but I wasn't sure who to
> send it to, since I'm not entirely sure exactly where the bug lives.
>  Without further ado:
> 
> Summary:
> When multiple threads simultaneously attempt to write to the same page of a
> file which has been mmapped using XIP for the first time, an unhandled
> EBUSY signal causes the kernel to panic.

Thanks a lot for your report, and all the info you carefully gathered.

I confess that I haven't looked at it at all!  Because I was thinking
maybe I should take a look, and when did we last hear from Carsten?
And though I now see more recent postings from him in other fields,
what came first to my eye was this nugget below.

It was white-space-damaged and wouldn't apply (I bet that's why it
got lost), so I've fixed that up and reformatted the description,
and added you as a Reporter - but otherwise it's as Carsten posted.

Hugh