[patch 1/1] MM: detach_vmas_to_be_unmapped fix

[patch 1/1] MM: detach_vmas_to_be_unmapped fix

[akuster]

---

 mm/mmap.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN mm/mmap.c~Avoiding-mmap-fragmentation_fixup mm/mmap.c
--- linux-2.6_clean/mm/mmap.c~Avoiding-mmap-fragmentation_fixup	2007-02-21 09:49:32.000000000 -0800
+++ linux-2.6_clean-akuster/mm/mmap.c	2007-02-21 09:51:26.000000000 -0800
@@ -1720,9 +1720,9 @@ detach_vmas_to_be_unmapped(struct mm_str
 	*insertion_point = vma;
 	tail_vma->vm_next = NULL;
 	if (mm->unmap_area == arch_unmap_area)
-		addr = prev ? prev->vm_end : mm->mmap_base;
+		addr = prev ? prev->vm_start : mm->mmap_base;
 	else
-		addr = vma ?  vma->vm_start : mm->mmap_base;
+		addr = vma ?  vma->vm_end : mm->mmap_base;
 	mm->unmap_area(mm, addr);
 	mm->mmap_cache = NULL;		/* Kill the cache. */
 }
_

Re: [patch 1/1] MM: detach_vmas_to_be_unmapped fix

[Ingo Oeser]

Hi,

On Wednesday, 21. February 2007, akuster@mvista.com wrote:
> 
> ---
> 
>  mm/mmap.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff -puN mm/mmap.c~Avoiding-mmap-fragmentation_fixup mm/mmap.c
> --- linux-2.6_clean/mm/mmap.c~Avoiding-mmap-fragmentation_fixup	2007-02-21 09:49:32.000000000 -0800
> +++ linux-2.6_clean-akuster/mm/mmap.c	2007-02-21 09:51:26.000000000 -0800
> @@ -1720,9 +1720,9 @@ detach_vmas_to_be_unmapped(struct mm_str
>  	*insertion_point = vma;
>  	tail_vma->vm_next = NULL;
>  	if (mm->unmap_area == arch_unmap_area)
> -		addr = prev ? prev->vm_end : mm->mmap_base;
> +		addr = prev ? prev->vm_start : mm->mmap_base;
>  	else
> -		addr = vma ?  vma->vm_start : mm->mmap_base;
> +		addr = vma ?  vma->vm_end : mm->mmap_base;
>  	mm->unmap_area(mm, addr);
>  	mm->mmap_cache = NULL;		/* Kill the cache. */
>  }

Please comment, why you think this is necessary.


Thanks & Regards

Ingo Oeser

Re: [patch 1/1] MM: detach_vmas_to_be_unmapped fix

[akuster]

Ingo Oeser wrote:
> Hi,
> 
> On Wednesday, 21. February 2007, akuster@mvista.com wrote:
>> ---
>>
>>  mm/mmap.c |    4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff -puN mm/mmap.c~Avoiding-mmap-fragmentation_fixup mm/mmap.c
>> --- linux-2.6_clean/mm/mmap.c~Avoiding-mmap-fragmentation_fixup	2007-02-21 09:49:32.000000000 -0800
>> +++ linux-2.6_clean-akuster/mm/mmap.c	2007-02-21 09:51:26.000000000 -0800
>> @@ -1720,9 +1720,9 @@ detach_vmas_to_be_unmapped(struct mm_str
>>  	*insertion_point = vma;
>>  	tail_vma->vm_next = NULL;
>>  	if (mm->unmap_area == arch_unmap_area)
>> -		addr = prev ? prev->vm_end : mm->mmap_base;
>> +		addr = prev ? prev->vm_start : mm->mmap_base;
>>  	else
>> -		addr = vma ?  vma->vm_start : mm->mmap_base;
>> +		addr = vma ?  vma->vm_end : mm->mmap_base;
>>  	mm->unmap_area(mm, addr);
>>  	mm->mmap_cache = NULL;		/* Kill the cache. */
>>  }
> 
> Please comment, why you think this is necessary.

Yes that would help.

On Feb. 16th I asked a question and got no response. Here is what should 
have been included with the above patch.

Wolfgang Wander submitted a fix to address a mmap fragmentation issue. 
The git patch ( 1363c3cd8603a913a27e2995dccbd70d5312d8e6 ) is somewhat 
different and yields different results when running Wolfgang's test case 
leakme.c.

IMHO, the vm start and end address are swapped in arch_unmap_area and 
arch_unmap_area_topdown functions.

Prior to this patch arch_unmap_area() used area->vm_start and 
arch_unmap_area_topdown used area->vm_end in the git patch the following 
change showed up.

if (mm->unmap_area == arch_unmap_area)
     addr = prev ? prev->vm_start : mm->mmap_base;
else
     addr = vma ?  vma->vm_end : mm->mmap_base;

Using Wolfgang Wander's leakme.c test, I get the same results seen with 
his original "Avoiding mmap fragmentation" patch as I do after swapping 
  the start & end address in the above code segment. The patch I 
submitted  addresses this typo issue.

TIA,
Armin

> 
> 
> Thanks & Regards
> 
> Ingo Oeser

Re: [patch 1/1] MM: detach_vmas_to_be_unmapped fix

[Andrew Morton]

> On Fri, 23 Feb 2007 08:27:00 -0800 akuster <akuster@mvista.com> wrote:
> Wolfgang Wander submitted a fix to address a mmap fragmentation issue. 
> The git patch ( 1363c3cd8603a913a27e2995dccbd70d5312d8e6 ) is somewhat 
> different and yields different results when running Wolfgang's test case 
> leakme.c.
> 
> IMHO, the vm start and end address are swapped in arch_unmap_area and 
> arch_unmap_area_topdown functions.
> 
> Prior to this patch arch_unmap_area() used area->vm_start and 
> arch_unmap_area_topdown used area->vm_end in the git patch the following 
> change showed up.
> 
> if (mm->unmap_area == arch_unmap_area)
>      addr = prev ? prev->vm_start : mm->mmap_base;
> else
>      addr = vma ?  vma->vm_end : mm->mmap_base;
> 
> Using Wolfgang Wander's leakme.c test, I get the same results seen with 
> his original "Avoiding mmap fragmentation" patch as I do after swapping 
>   the start & end address in the above code segment. The patch I 
> submitted  addresses this typo issue.

That's still not an adequate or terribly useful changlog, sorry.

Please tell us exactly what this patch does, without referring to some other
patch which I cannot remember nor presently access.

I particular, before-and-after testing results would be useful so we can
see what the effect of this change is.

Also, please send a Signed-of-by: for this work, thanks.