Re: Infinite loop in task_dentry_path

[David Smith <dsmith at redhat dot com>]

On 05/22/2014 04:49 PM, Henrik /KaarPoSoft wrote:
> On 05/22/2014 05:38 PM, David Smith wrote:
>> On 05/09/2014 04:23 PM, Henrik /KaarPoSoft wrote:
>>> On 05/09/2014 05:29 PM, David Smith wrote:
>>>> On 05/08/2014 05:34 PM, Henrik /KaarPoSoft wrote:
>>> Here is how to reproduce:
>>
>> Ah, that does reproduce the problem for me on a rawhide system (I
>> haven't tried other places). When I add you patch to task_dentry_path(),
>> it does get farther, but then I get a read fault. I'll have to dig
>> deeper.
>>
>>>
>>> The patch is probably wrong, and I hope that someone more
>>> knowledgeable than me may come up with a better one.
>>>
>>> However, if I look at the comment about task_dentry_path in
>>> https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=blob;f=tapset/linux/dentry.stp
>>>
>>>
>>> it seems to me that is based on the kernel's d_path().
>>>
>>> And the comment in the top of
>>> http://lxr.free-electrons.com/source/fs/dcache.c#L3052
>>> says something about "synthetic filesystems",
>>> and just maybe this is doing something to overcome the problem.
>>
>> Hmm, interesting. Thanks for the pointer.

I went ahead and filed PR16991 (infinite loop in task_dentry_path) on
this issue, you should be CC'ed on it.

> I hope that you will be able to find a more generic solution
> than my lame patch!

Your patch isn't lame, I'm just not sure it is quite correct. I've spend
a couple of days trying to figure out what is going on here and the best
way to fix it. I may end up using your patch yet.

Hopefully I'll have something for you to try soon.

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
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