Use of chunksize before initialization

Ivan A. Kosarev ivan at
Sat Mar 21 09:20:43 UTC 2015

On 03/21/2015 03:02 AM, Konstantin Belousov wrote:
> On Fri, Mar 20, 2015 at 03:59:52PM +0200, Ivan A. Kosarev wrote:
>> #12 0x00000008011b428d in malloc_init_hard () at jemalloc_jemalloc.c:698
>> #13 malloc_init () at jemalloc_jemalloc.c:296
>> #14 0x0000000801243ea2 in ?? () from /lib/
>> #15 0x00000008006a5400 in ?? ()
>> #16 0x000000080089e5b0 in ?? () from /libexec/
>> #17 0x00007fffffffe0b0 in ?? ()
>> #18 0x0000000801139d06 in _init () from /lib/
>> #19 0x00007fffffffe0b0 in ?? ()
> The backtrace is strange.  Did you compiled malloc with the debugging
> symbols, while keep rest of libc without -g ?

I've just added the -g flag to CC_FLAGS in the Makefile and made sure to 
install an unstripped version of the .so . I could investigate more on 
why the early calls omit debug symbols, if it does any matter.

> Does it happen always, on only for the early initialization of the
> mutexes ?

I'm not sure I understand the whole logic of the initialization process, 
but we could put a statement initializing the chunksize variable to 0 to 
the beginning of malloc_init_hard() and see if the assertion (or any 
other before it) fails. Since my suspicion is that the variable get 
random values at base_boot(), the presence of the failure depends on 
random factors. For a simple one-line program calling malloc() it is 
known to not to fail, of course. I should be able to to more tests on Mon.

>    It might be related to r276630.  Can you test on, say, 10.1 ?

The Tsan tests mentioned below that cause mass (alignment != 0) failures 
are known to work fine on 10.1.

> <jemalloc>: jemalloc_chunk.c:152: Failed assertion: "alignment != 0"
> Here's more of failures of this kind around:
> Can you please let me know if the analysis is correct and there's
> something to fix about initialization of the variable?
> Backtrace looks valid.



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