Re: call_rcu from trace_preempt

From: Alexei Starovoitov
Date: Tue Jun 16 2015 - 02:47:00 EST

On 6/15/15 11:34 PM, Daniel Wagner wrote:
On 06/16/2015 08:25 AM, Alexei Starovoitov wrote:
On 6/15/15 11:06 PM, Daniel Wagner wrote:
with the above 'fix' the trace.patch is now passing.
It still crashes for me with the original test program

[ 145.908013] [<ffffffff810d1da1>] ? __rcu_reclaim+0x101/0x3d0
[ 145.908013] [<ffffffff810d1ca0>] ? rcu_barrier_func+0x250/0x250
[ 145.908013] [<ffffffff810abc03>] ?
[ 145.908013] [<ffffffff810d9afa>] rcu_do_batch+0x2ea/0x6b0

yes. full bpf test still crashes.
That's why I said trace.patch is passing ;)
There is something else in there. One 'fix' at a time.

Ah, sorry, I read it is working now :) Anyway, I'll keep looking
as well.

Yesterday I wrote a small torture program for the map
implementation. Just to rule out memory corruption there.
Are you interested in it? If yes I could clean it a bit.

of course!
We already have samples/bpf/test_maps.c that stresses map
access from user space and lib/test_bpf.c that stress JIT
and interpreter from the kernel.
Looking at your test, I think it doesn't buy as much doing it
from the kernel?
If so, I think would be great to add it to test_maps.c

Will read it more carefully tomorrow.

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