Crash on kmalloc with GFP_KERNEL

[Francois Cartegnie]

Hello,

I'm currently extending the u32 classifier (linux traffic control).
I've experienced some strange behaviour with memory allocation :
A single kmalloc with GFP_KERNEL leads to kernel panic (BUG, slab.c) when 
there's multiple requests matching the classifier. 
Thinking about concurrent access, I tried to lock the allocation with 
semaphores.
The only way to solve it was to use GFP_ATOMIC (but I also experienced It 
still crash in some cases).

This is really similar to the bug report made on netfilter buzilla:
https://bugzilla.netfilter.org/cgi-bin/bugzilla/show_bug.cgi?id=68

So I guess the memory allocations are interrupted by arrival of new packets 
and then crash.
-Is there any way to fix it to use GFP_KERNEL memory allocations ?

-Also, the original u32 code uses GFP_KERNEL for storing it's matching rules. 
I guess It would crash here too if the rules are created under heavy network 
traffic. Any idea ?


Greetings,

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