Re: [boost] [simple_segregated_storage] segfault

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 
news:6F6A2FC198A0F943ACC2259C38A2E30B6B6FB4BD9E_at_EXCHANGE-AH.ad.mathworks.com...
>> 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 
boost::pool<boost::default_user_allocator_new_delete>::ordered_malloc 
(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 
boost::detail::sh::shifted<std::_List_node<boost::detail::sh::shifted_ptr<vector>, 
boost::detail::sh::shifted_allocator<boost::detail::sh::shifted_ptr<vector> 
 > > >::operator new (s=68)
    at sh_owned_base_nt.hpp:213
#5  0x00423202 in 
boost::detail::sh::shifted_allocator<std::_List_node<boost::detail::sh::shifted_ptr<vector>, 
boost::detail::sh::shifted_allocator<boost::detail::sh::shifted_ptr<vector> 
 > > >::allocate (this=0x3e2d6c, s=1)
    at shifted_allocator.hpp:83
#6  0x00452436 in std::_List_base<boost::detail::sh::shifted_ptr<vector>, 
boost::detail::sh::shifted_allocator<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>, 
boost::detail::sh::shifted_allocator<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>, 
boost::detail::sh::shifted_allocator<boost::detail::sh::shifted_ptr<vector> 
 > >::_M_insert (this=0x3e2d6c, __position={_M_node = 0x3e2da0}, 
__x=@0x22ff24)
    at stl_list.h:1187
#9  0x00463218 in std::list<boost::detail::sh::shifted_ptr<vector>, 
boost::detail::sh::shifted_allocator<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

-Phil