[uml-devel] The init_maps bug which cause mem map error

[uml-devel] The init_maps bug which cause mem map error

[wang lianwei]

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 There is a bug In file
    linux/arch/um/kernel/physmem.c  init_mem() functions:

*int* *init_maps*(*unsigned* *long* physmem, *unsigned* *long* iomem,
*unsigned* *long* highmem)
{
	*struct* page *p, *map;
	*unsigned* *long* phys_len, phys_pages, highmem_len, highmem_pages;
	*unsigned* *long* iomem_len, iomem_pages, total_len, total_pages;
	*int* i;

	phys_pages = physmem >> PAGE_SHIFT;
	phys_len = phys_pages * *sizeof*(*struct* page);

	iomem_pages = iomem >> PAGE_SHIFT;
	iomem_len = iomem_pages * *sizeof*(*struct* page);

	highmem_pages = highmem >> PAGE_SHIFT;
	highmem_len = highmem_pages * *sizeof*(*struct* page);

	total_pages = phys_pages + iomem_pages + highmem_pages;
	total_len = phys_len + iomem_pages + highmem_len;

	*if*(kmalloc_ok){
		map = kmalloc(total_len, GFP_KERNEL);
		*if*(map == NULL)
			map = vmalloc(total_len);
	}
	*else* map = alloc_bootmem_low_pages(total_len);

	*if*(map == NULL)
		*return*(-ENOMEM);

	*for*(i = 0; i < total_pages; i++){
		p = &map[i];
		set_page_count(p, 0);
		SetPageReserved(p);
		INIT_LIST_HEAD(&p->list);
	}

	mem_map = map;
	max_mapnr = total_pages;
	*return*(0);
}

this line should be

total_len = phys_len + iomem_len + highmem_len;


 <http://cvs.sourceforge.net/viewcvs.py/user-mode-linux/linux/#dirlist>

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Re: [uml-devel] The init_maps bug which cause mem map error

[Blaisorblade]

On Tuesday 10 January 2006 15:14, wang lianwei wrote:
>  There is a bug In file
>     linux/arch/um/kernel/physmem.c  init_mem() functions:

Yep, right...

> *int* *init_maps*(*unsigned* *long* physmem, *unsigned* *long* iomem,
> *unsigned* *long* highmem)
> {
> 	*struct* page *p, *map;
> 	*unsigned* *long* phys_len, phys_pages, highmem_len, highmem_pages;
> 	*unsigned* *long* iomem_len, iomem_pages, total_len, total_pages;
> 	*int* i;

(What happened to these bad "*" guys ;-) ? )

> 	phys_pages = physmem >> PAGE_SHIFT;
> 	phys_len = phys_pages * *sizeof*(*struct* page);

> 	iomem_pages = iomem >> PAGE_SHIFT;
> 	iomem_len = iomem_pages * *sizeof*(*struct* page);

> 	highmem_pages = highmem >> PAGE_SHIFT;
> 	highmem_len = highmem_pages * *sizeof*(*struct* page);

> 	total_pages = phys_pages + iomem_pages + highmem_pages;

> 	total_len = phys_len + iomem_pages + highmem_len;

> this line should be

That line should be the below one, right (it wasn't clear the line you were 
correcting, I later grasped it)? I think you're fully right (and I've never 
seen iomem working very well, so I tend to agree).

> total_len = phys_len + iomem_len + highmem_len;

Remember people: never compare apples with bananas (or whatever). Thanks for 
the note. It's the first patch on my queue.

>  <http://cvs.sourceforge.net/viewcvs.py/user-mode-linux/linux/#dirlist>

-- 
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Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	
	
		
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Re: [uml-devel] The init_maps bug which cause mem map error

[Jeff Dike]

On Wed, Jan 11, 2006 at 12:39:59AM +0100, Blaisorblade wrote:
> On Tuesday 10 January 2006 15:14, wang lianwei wrote:
> (What happened to these bad "*" guys ;-) ? )

Yeah, this would have been better expressed as a patch.

> > total_len = phys_len + iomem_len + highmem_len;
>
> Remember people: never compare apples with bananas (or whatever).

Yup, sometimes I wish we had strongly typed integers...

> Thanks for
> the note. It's the first patch on my queue.

OK, I was going to fix it here, but I'll just let you send it in.

Does this fix the 2M iomem problem?

                                Jeff


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Re: [uml-devel] The init_maps bug which cause mem map error

[Blaisorblade]

On Wednesday 11 January 2006 17:21, Jeff Dike wrote:
> On Wed, Jan 11, 2006 at 12:39:59AM +0100, Blaisorblade wrote:
> > On Tuesday 10 January 2006 15:14, wang lianwei wrote:
> > (What happened to these bad "*" guys ;-) ? )

> Yeah, this would have been better expressed as a patch.

> > > total_len = phys_len + iomem_len + highmem_len;

> > Remember people: never compare apples with bananas (or whatever).

> Yup, sometimes I wish we had strongly typed integers...

Yeah :-] ...

I think in Java APIs tend to do almost that... not at that point, but they use 
distinct classes for Point and Dimension and Rectangle and whatsoever... and 
I even have to study these things.

> > Thanks for
> > the note. It's the first patch on my queue.

> OK, I was going to fix it here, but I'll just let you send it in.

Will be in my next queue flush...

> Does this fix the 2M iomem problem?

Ah, well, he's the reporter of that problem, and he also worked diagnosing 
it... compliments!

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	
	
		
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Re: [uml-devel] The init_maps bug which cause mem map error

[Jeff Dike]

On Wed, Jan 11, 2006 at 04:52:38PM +0100, Blaisorblade wrote:
> > Yup, sometimes I wish we had strongly typed integers...
> 
> Yeah :-] ...

But, a nanosecond later, I think about the insanity of bytes_to_page(), 
foo_to_bar(), etc converters that would be needed...

> Ah, well, he's the reporter of that problem, and he also worked diagnosing 
> it... compliments!

Indeed, I just wanted to make sure that fixed it.

				Jeff


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