Crash when memset of shared mapped memory in ARM

[Dave Martin]

On Wed, Nov 16, 2011 at 11:54:35AM +0000, Will Deacon wrote:
> (Replying to Russell so as to lose the -request addresses)
> 
> On Wed, Nov 16, 2011 at 08:45:47AM +0000, Russell King - ARM Linux wrote:
> > Please do not spam mailing lists -request addresses when you post.  The
> > -request addresses are there for you to give the mailing list software
> > _instructions_ on what to do with your subscription.  It is not for
> > posts to the mailing list.
> 
> For what it's worth, I was brave/daft enough to compile and run the testcase
> with an -rc1 kernel and Linaro 11.09 filesystem on the quad A9 Versatile
> Express:
> 
> root at dancing-fool:~# ./yad
> mmap: addr 0x20000000
> root at dancing-fool:~# ./yad
> shm_open: File exists
> mmap: addr 0x20000000
> 
> Looks like I'm missing the fireworks, despite the weirdy MAP_SHARED |
> MAP_FIXED mmap flags.

I did't see any problem on a random 3.1-rc4 kernel either on A9...

(Since when was MAP_SHARED "weirdy"...?)

Cheers
---Dave