Re: RFC: enhanced memory protection support

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 30.04.2012 17:26, Bean wrote:
> Hi,
>
> While testing network function in efi mode, I've found several memory
> leak related to fragmentation, but there is still some memory problem
> that's very tricky to locate. For example, you can run testspeed on a
> large file several times in a row and it could show the memory error.
> Since network condition are very difficult to reproduce, I have to
> look at the source of this issue, memory allocation. Currently it has
> mm_debug option that could print out file and line number of each
> memory call, but it's quite useless since we can't find the relevant
> informaton with full screen of prints.
> Here are some of my ideas for enhanced memory protection support:
>
> 1, when we allocate memory, we append some information at the end of
> the buffer, which include filename, lineno of caller, and tag to
> indicate what is used for and some padding to detect memory overwrite
> problem.
>
> 2. add a command to print the current memory list with extended
> information, this can be used to find memory leaks.
>
> 3. it's also a good idea to run the memory check in automated test to
> locate potential issue.
This is pretty easy to do leveraging some of the code I did for POSIX
support. But:
- Due to additional time and space required it should be done only when
mm-debug is enabled.
- The additional data has to be stored before rather than after the
range since we store all the info before.
- Integrating with automated tests isn't that easy since some memory is
intentionally never freed i.a. disk cache or otherwise in use (i.a.
terminal). We need exceptions for those.
I have half-working patch, just needs few fixes.


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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