Boost logo

Boost :

Subject: Re: [boost] [simple_segregated_storage] segfault
From: Phil Bouchard (philippe_at_[hidden])
Date: 2008-10-01 12:05:39

"Chris Newbold" <Chris.Newbold_at_[hidden]> wrote in message
>> From: boost-bounces_at_[hidden]
>> [mailto:boost-bounces_at_[hidden]]
>> On Behalf Of Chris Newbold
>> Sent: Wednesday, October 01, 2008 7:58 AM
>> With your latest updates to the shifted_ptr code I've been able to
>> compile
>> w/ GCC 4.1.2 and reproduce a crash; it looks a little different than the
>> one you posted, but at least now I've got something to dig into. Stay
>> tuned.
> Phil--
> I believe that this crash is actually a bug in your code. In
> boost::detail::sh::pool::allocate you are dividing the specified size by
> the pool's chunk size. However, in deallocate, you are just passing the
> size directly to the underlying pool. The result is that you are trying to
> free twice as many chunks as you allocated.
> Take a look and let me know what you think.

My mistake. I forgot taking the chunk_size_ away and relying on array of
chars. Now here is the crash I got:

#0 0x0041ca66 in boost::simple_segregated_storage<unsigned
int>::try_malloc_n (start=@0x22fcdc, n=16, partition_size=4)
    at simple_segregated_storage.hpp:234
#1 0x0041cb58 in boost::simple_segregated_storage<unsigned int>::malloc_n
(this=0x48d030, n=17, partition_size=4)
    at simple_segregated_storage.hpp:256
#2 0x00420a4d in
(this=0x48d030, n=68)
    at pool.hpp:511
#3 0x004238c9 in boost::detail::sh::pool::allocate (this=0x48d030, s=68)
    at sh_owned_base_nt.hpp:103
#4 0x0042a3fa in
> > >::operator new (s=68)
    at sh_owned_base_nt.hpp:213
#5 0x00423202 in
> > >::allocate (this=0x3e2d6c, s=1)
    at shifted_allocator.hpp:83
#6 0x00452436 in std::_List_base<boost::detail::sh::shifted_ptr<vector>,
> >::_M_get_node (this=0x3e2d6c)
    at stl_list.h:333
#7 0x00463124 in std::list<boost::detail::sh::shifted_ptr<vector>,
> >::_M_create_node (this=0x3e2d6c, __x=@0x22ff24)
    at stl_list.h:457
#8 0x004631e0 in std::list<boost::detail::sh::shifted_ptr<vector>,
> >::_M_insert (this=0x3e2d6c, __position={_M_node = 0x3e2da0},
    at stl_list.h:1187
#9 0x00463218 in std::list<boost::detail::sh::shifted_ptr<vector>,
> >::push_back (this=0x3e2d6c, __x=@0x22ff24)
    at stl_list.h:808
#10 0x004016e6 in main ()
    at shifted_ptr_test2.cpp:102


Boost list run by bdawes at, gregod at, cpdaniel at, john at