Re: Possible broken MM code in dell-laptop.c?

[Michal Hocko <mhocko@suse.cz>]

On Mon 15-06-15 23:27:59, Pali Rohar wrote:
> On Monday 15 June 2015 23:18:16 Michal Hocko wrote:
> > On Sun 14-06-15 11:05:07, Pali Rohar wrote:
> > > Hello,
> > > 
> > > in drivers/platform/x86/dell-laptop.c is this part of code:
> > > 
> > > static int __init dell_init(void)
> > > {
> > > ...
> > > 
> > > 	/*
> > > 	
> > > 	 * Allocate buffer below 4GB for SMI data--only 32-bit physical
> > > 	 addr * is passed to SMI handler.
> > > 	 */
> > > 	
> > > 	bufferpage = alloc_page(GFP_KERNEL | GFP_DMA32);
> > 
> > [...]
> > 
> > > 	buffer = page_address(bufferpage);
> > 
> > [...]
> > 
> > > fail_rfkill:
> > > 	free_page((unsigned long)bufferpage);
> > 
> > This one should be __free_page because it consumes struct page* and
> > it is the proper counter part for alloc_page. free_page, just to
> > make it confusing, consumes an address which has to be translated to
> > a struct page.
> > 
> > I have no idea why the API has been done this way and yeah, it is
> > really confusing.
> > 
> > [...]
> > 
> > > static void __exit dell_exit(void)
> > > {
> > > ...
> > > 
> > > 	free_page((unsigned long)buffer);
> 
> So both, either:
> 
>  free_page((unsigned long)buffer);
> 
> or
> 
>  __free_page(bufferpage);
> 
> is correct?

Yes. Although I would use __free_page variant as both seem to be
globally visible.

-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>