lkml.org 
[lkml]   [2015]   [Jan]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v10 13/17] mm: vmalloc: add flag preventing guard hole allocation
On 01/30/2015 02:12 AM, Andrew Morton wrote:
> On Thu, 29 Jan 2015 18:11:57 +0300 Andrey Ryabinin <a.ryabinin@samsung.com> wrote:
>
>> For instrumenting global variables KASan will shadow memory
>> backing memory for modules. So on module loading we will need
>> to allocate shadow memory and map it at exact virtual address.
>
> I don't understand. What does "map it at exact virtual address" mean?
>

I mean that if module_alloc() returned address x, than
shadow memory should be mapped exactly at address kasan_mem_to_shadow(x).

>> __vmalloc_node_range() seems like the best fit for that purpose,
>> except it puts a guard hole after allocated area.
>
> Why is the guard hole a problem?
>

Because of guard hole in shadow some future allocations of shadow memory
will fail. Requested address ( kasan_mem_to_shadow(x) ) will be already occupied
by guard hole of previous allocation.




\
 
 \ /
  Last update: 2015-01-30 19:01    [W:0.166 / U:0.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site