Malloc / free ansd rump_fs ->Slab-backend exhausted

Stefan Kalkowski stefan.kalkowski at ...1...
Wed Sep 3 15:14:48 CEST 2014

Hello Wolfgang,

I've examined the problem, in fact there are to bugs in the blk_cache
that prevented the rump server from working. Please try out the
following two patches:

or use directly my topic branch for testing it:

Nevertheless, I've experienced problems when doing the rump_fs server,
and corresponding VFS example application. Rump might leave the file
system in an inconsistent state so that you can't run the test twice on
the same filesystem. Maybe just a missing 'sync' in the client
application? But I'm not familiar with the inner workings of the rump
filesystem server, nor the libc tests.


On 09/03/2014 12:08 PM, Stefan Kalkowski wrote:
> Hi,
> On 09/02/2014 09:11 PM, w_schmidt at ...181... wrote:
>> Hi,
>> did Stefan had time to look into the issue with the block cache?
> I'm afraid no, I didn't had the time. To reproduce your experienced
> problems easily, it would be nice to have a complete and working
> run-script, as well as the whole output of the broken, and of the intact
> scenario. Moreover, if you've changed, or added any code, a topic branch
> or at least a patch would be nice.
> Now, I've built my own script outgoing from the "" script
> (attachment), and try to look into the issue.
> Regards
> Stefan
>> Best regards,
>> Wolfgang
>> -----Ursprüngliche Nachricht----- 
>> From: Sebastian Sumpf
>> Sent: Thursday, August 21, 2014 8:40 PM
>> To: Genode OS Framework Mailing List
>> Subject: Re: Malloc / free ansd rump_fs ->Slab-backend exhausted
>> Hi Wolfgang,
>> On 08/18/2014 08:09 PM, w_schmidt at ...181... wrote:
>>> Hi,
>>>>> this seems to be happen only if rump_fs has a larger quota – the file
>>>>> can be larger if rump_fs has a smaller quota. (memory tests of the
>>>>> system have shown no errors so RAM should be okay)
>>>> this is indeed very strange. I hope you have a Genode version where
>>>> there is no Slab-Backend allocator, have a look at
>>> '>include/util/allocator_fap.h" in the dde_rump repository, there should
>>>> only be a PERR message with the slab warning left.
>>> The file looks like below,
>> Yes, that is the right one. We most likely got a problem with memory
>> accounting in this case. Regarding your block cache question: The block
>> cache has not really been tested up until now, so there may still be
>> bugs. If you could provide a branch (e.g., on GitHub) or a run script, I
>> might be able to have a look at it. On the other hand, Stefan will be
>> back next week and, since wrote the thing, he might be able to clear
>> things up.
>> Cheers,
>> Sebastian
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Stefan Kalkowski
Genode Labs ·

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