[PATCH] mempool: add missing include

[David Rientjes]

On Thu, 9 Apr 2015, Arnd Bergmann wrote:

> > > This is a fix^3 for the mempool poisoning patch, which introduces
> > > a compile-time error on some ARM randconfig builds:
> > > 
> > > mm/mempool.c: In function 'check_element':
> > > mm/mempool.c:65:16: error: implicit declaration of function 'kmap_atomic' [-Werror=implicit-function-declaration]
> > >    void *addr = kmap_atomic((struct page *)element);
> > > 
> > > The problem is clearly the missing declaration, and including
> > > linux/highmem.h fixes it.
> > > 
> > > Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> > > Fixes: a3db5a8463b0db ("mm, mempool: poison elements backed by page allocator fix fix")
> > 
> > Acked-by: David Rientjes <rientjes at google.com>
> > 
> > Thanks!  Can you confirm that this is because CONFIG_BLOCK is disabled and 
> > not something else?
> 
> Unfortunately I've lost the information which build was responsible
> for this error (normally I keep it, but my script failed here because the
> same config introduced two new regressions). CONFIG_BLOCK sounds plausible
> here.
> 
> If necessary, I can repeat the last few hundred builds without this
> patch to find out what it was.
> 

Ok, thanks.  The only reason I ask is because if this is CONFIG_BLOCK then 
it shouldn't be arm specific and nothing else has reported it.  I'll do a 
randconfig loop with my arm cross-compiler and see if I can find any other 
issues.