Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Fawad Lateef]

Hello,

I m facing a problem in RHEL3 (2.4.21-5.ELsmp) kernel while using
kmap_atomic on the pages reserved at the boot time !!!!

At the boot time I reserved pages above 2GB for later use by my module
..... And when I was using those reserved pages through kmap_atomic
system hangs; although kmap_atomic successfully returns me the virtual
address but when I use that virtual address like in memcpy the system
hangs .....

I m unable to findout why it is happening in RHEL3 kernel !!!! Plz
help me in this regard ....

-- 
Fawad Lateef


P.S.

My memory reservation and later using that memory through kmap_atomic
works well on the kernels other than RHEL3 2.4.21-e.ELsmp  
.............. the page reservation was done in the
arch/i386/mm/init.c file in function one_highpage_init ...... I have
Machine with 16GB RAM and 2 - Xeon 2.4GHz Processors .....

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Nish Aravamudan]

On 8/7/05, Fawad Lateef <fawadlateef@gmail.com> wrote:
> Hello,
> 
> I m facing a problem in RHEL3 (2.4.21-5.ELsmp) kernel while using
> kmap_atomic on the pages reserved at the boot time !!!!

Unless you can reproduce this in a current kernel.org kernel
(2.6.13-rc6), then you probably should contact RedHat for support.

Thanks,
Nish

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Zachary Amsden]

Fawad Lateef wrote:

>Hello,
>
>I m facing a problem in RHEL3 (2.4.21-5.ELsmp) kernel while using
>kmap_atomic on the pages reserved at the boot time !!!!
>
>At the boot time I reserved pages above 2GB for later use by my module
>..... And when I was using those reserved pages through kmap_atomic
>system hangs; although kmap_atomic successfully returns me the virtual
>address but when I use that virtual address like in memcpy the system
>hangs .....
>
>I m unable to findout why it is happening in RHEL3 kernel !!!! Plz
>help me in this regard ....
>  
>

IIRC 2.4.21 has some highmem bugs that have since been fixed.  But, it 
sounds like you might be doing something quite unusual.  Code would 
definitely give people a better idea of what might be wrong.  You should 
definitely consider moving to 2.6 to get a better response.

Zach

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Fawad Lateef]

On 8/8/05, Zachary Amsden <zach@vmware.com> wrote:
> 
> IIRC 2.4.21 has some highmem bugs that have since been fixed.  But, it
> sounds like you might be doing something quite unusual.  Code would
> definitely give people a better idea of what might be wrong.  

I think you overlooked what i mentioned in P.S. ; which is 

My memory reservation and later using that memory through kmap_atomic
works well on the kernels other than RHEL3 2.4.21-e.ELsmp
.............. the page reservation was done in the
arch/i386/mm/init.c file in function one_highpage_init ...... I have
Machine with 16GB RAM and 2 - Xeon 2.4GHz Processors .....

The code which I added for memory reservation in kernel is : 

void __init one_highpage_init(struct page *page, int pfn, int bad_ppro)
{
	if (!page_is_ram(pfn)) {
		SetPageReserved(page);
		return;
	}
	
	if (bad_ppro && page_kills_ppro(pfn)) {
		SetPageReserved(page);
		return;
	}

// Here's the code which i added for memory reservation ..... i m
setting 0xC4 in page->count just because i will know later that these
pages have been reserved by me ... not by kernel .....

	if ((unsigned long)(page - mem_map) > 0x80000) {
		SetPageReserved(page);
		set_bit(PG_highmem, &page->flags);
		atomic_set(&page->count, 0xC4);
		totalhigh_pages++;
		return;
	}

// My code Ends here 
	
	ClearPageReserved(page);
	set_bit(PG_highmem, &page->flags);
	atomic_set(&page->count, 1);
	__free_page(page);
	totalhigh_pages++;
}


After this in my module, i simply use kmap_atomic to map the page
reserved by me and tried to use that ........ its working perfect in
both 2.4.x series and also working in 2.6.x .....

> You should definitely consider moving to 2.6 to get a better response.
> 

i already moved to 2.6.x already !!! but the current requiment is to
use RHEL3 Kernel which is 2.4.21-27.ELsmp

I think its now more clear !!!! waiting for your resposes !!!


-- 
Fawad Lateef

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Zachary Amsden]

Fawad Lateef wrote:

>	if ((unsigned long)(page - mem_map) > 0x80000) {
>		SetPageReserved(page);
>		set_bit(PG_highmem, &page->flags);
>		atomic_set(&page->count, 0xC4);
>  
>

That seems like a hackish thing to do.  Could you mistake other pages 
with the same count as pages you have reserved?

>After this in my module, i simply use kmap_atomic to map the page
>reserved by me and tried to use that ........ its working perfect in
>both 2.4.x series and also working in 2.6.x .....
>  
>

This suggests a problem with RHEL3.  If it works fine on a vanilla 2.4 
kernel, then by all means try to get support from your vendor.  If it 
works fine on the latest 2.4.X and 2.6.X linux-kernel is probably not 
the best place to look for help, although I can't blame you for trying.  
Maybe someone here already knows the answer, but unfortunately, it is 
not me.

Sorry if I missed context from your earlier posts.

Zach

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Arjan van de Ven]

On Mon, 2005-08-08 at 08:50 +0500, Fawad Lateef wrote:
> Hello,
> 
> I m facing a problem in RHEL3 (2.4.21-5.ELsmp) kernel while using
> kmap_atomic on the pages reserved at the boot time !!!!
> 
> At the boot time I reserved pages above 2GB for later use by my module
> ..... And when I was using those reserved pages through kmap_atomic
> system hangs; although kmap_atomic successfully returns me the virtual
> address but when I use that virtual address like in memcpy the system
> hangs .....

1) you probably should use RH support for this
2) you forgot to attach your sourcecode / URL to that, including the
   full source of your module.

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Fawad Lateef]

Dear Arjan,

On 8/8/05, Arjan van de Ven <arjan@infradead.org> wrote:
> 
> 1) you probably should use RH support for this
> 2) you forgot to attach your sourcecode / URL to that, including the
>    full source of your module.
> 

I already mentioned my code and some details in my previous mail on
the list !!!! Can u check and help me out or I hav to send that again
???? And as far as Redhat Support concerns that problem is not related
to Redhat because I reserved memory by placing the code in the
arch/i386/mm/init.c file in one_highpage_init function not through
mem= option of the kernel ......

Waiting for your response and help .....


-- 
Fawad Lateef

Re: Highmemory Problem with RHEL3 .... 2.4.21-5.ELsmp

[Arjan van de Ven]

On Mon, 2005-08-08 at 22:24 +0500, Fawad Lateef wrote:
> Dear Arjan,
> 
> On 8/8/05, Arjan van de Ven <arjan@infradead.org> wrote:
> > 
> > 1) you probably should use RH support for this
> > 2) you forgot to attach your sourcecode / URL to that, including the
> >    full source of your module.
> > 
> 
> I already mentioned my code and some details in my previous mail on
> the list !!!! 

No you didn't; you didn't post the module only a rough description of
what you changed.... the module is the part that uses this stuff (and
since it needs core kernel changes, is required to be GPL so I see no
problem posting a URL to it)