On 02/04/2014 19:44, Kevin Greenan wrote:
> Hey Loic,
> 
> Are you ensuring that Jerasure (actually gf-complete) is getting memory 
> buffers aligned on 16-byte boundaries?  Without looking too deep, that is the 
> first thing I would check.
> 

Yes

https://github.com/ceph/ceph/blob/master/src/erasure-code/jerasure/ErasureCodeJerasure.cc#L32
https://github.com/ceph/ceph/blob/master/src/erasure-code/jerasure/ErasureCodeJerasure.cc#L242
https://github.com/ceph/ceph/blob/master/src/erasure-code/jerasure/ErasureCodeJerasure.cc#L65
https://github.com/ceph/ceph/blob/master/src/erasure-code/jerasure/ErasureCodeJerasure.cc#L108

I'll re-read this logic tomorrow just to be sure.

Cheers

> I can have a deeper look later today or tomorrow.
> 
> -kevin
> 
> 
> On Wed, Apr 2, 2014 at 10:35 AM, Loic Dachary <[email protected] 
> <mailto:[email protected]>> wrote:
> 
>     Hi Kevin,
> 
>     In the context of http://tracker.ceph.com/issues/7914 we're trying to 
> figure out why jerasure dumps core. We don't know how to reproduce it yet 
> (ran dozens of identical tests suites with no such crash in the past few 
> days, which is to be expected for rare bugs because the test suite introduces 
> random errors / failures on purpose).
> 
>     The full stack trace is at http://tracker.ceph.com/issues/7914#note-24 
> but the relevant part is here:
> 
>     #0  0x00007f4756779b7b in raise (sig=<optimized out>) at 
> ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:42
>     #1  0x0000000000981b4e in reraise_fatal (signum=11) at 
> global/signal_handler.cc:59
>     #2  handle_fatal_signal (signum=11) at global/signal_handler.cc:105
>     #3  <signal handler called>
>     #4  0x0000000000000000 in ?? ()
>     #5  0x00007f47385ae6b1 in jerasure_matrix_dotprod (k=2, w=8, 
> matrix_row=0x31513a8, src_ids=0x0, dest_id=<optimized out>, 
> data_ptrs=0x7f4741ec7a00, coding_ptrs=0x7f4741ec7a10,
>         size=2048) at erasure-code/jerasure/jerasure/src/jerasure.c:607
>     #6  0x00007f47385ae7d6 in jerasure_matrix_encode (k=2, m=1, w=8, 
> matrix=<optimized out>, data_ptrs=0x7f4741ec7a00, coding_ptrs=0x7f4741ec7a10, 
> size=2048)
>         at erasure-code/jerasure/jerasure/src/jerasure.c:310
>     ...
> 
>     Note that this jerasure/gf-complete combination has been compiled with 
> SSE4.1, SSE4.2, PCLMUL, SSSE3, SSE3, SSE2, SSE flags activated. These are 
> jerasure v2 and gf-complete v1, only slightly modified as found in 
> https://github.com/ceph/jerasure/tree/v2-ceph and 
> https://github.com/ceph/gf-complete/tree/v1-ceph (all commits there have a 
> pending pull request under https://bitbucket.org/jimplank/gf-complete 
> https://bitbucket.org/jimplank/jerasure, nothing you've not seen before).
> 
>     #5 is https://github.com/ceph/jerasure/blob/v2-ceph/src/jerasure.c#L607
> 
>     and then it dives into gf-complete and most probably destroyed part of 
> the stack when corrupting memory. I'll be chasing this tomorrow. If you have 
> a brilliant idea on why that happens, I'll take it ;-)
> 
>     Cheers
> 
>     --
>     Loïc Dachary, Artisan Logiciel Libre
> 
> 

-- 
Loïc Dachary, Artisan Logiciel Libre

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