two 4GB mallocs => SEGV

Peter Pentchev roam at
Thu Oct 28 03:53:47 PDT 2004

On Tue, Oct 26, 2004 at 02:47:06PM +0200, Willem Jan Withagen wrote:
> Georgi Guninski wrote:
> >on a freebsd amd64 box with more than 8GB swap i experience the following:
> >amdkotef64# cat test.c
[snip 2 * 4GB malloc]
> >amdkotef64# gcc test.c
> >amdkotef64# ./a.out 
> >100000000
> >503000
> >/: write failed, filesystem is full
> >Segmentation fault
> These 2 lines stem from the fact that the program is being dumped and there 
> is not enough space to dump the full size core of that program.
> what does swapinfo tell you during the the run of the program???
> I ran malloc tests in 4Gb with 5Gb of swap, which it nicely completely 
> filled, and then in faulted, because there was no more space.
> This behaviour can be set, I think. Check man 5 malloc.conf, and check 
> /etc/malloc.conf to see if you've got the X-flag on.

But shouldn't malloc() write out an 'out of memory' message before the
core dump then?  There's no such message in Georgi's output.

It's true that when he asked me on Saturday about this, I completely
forgot about malloc's X flag, but I don't think he's using it, and even
if he were, there ought to be a message there.

> I have malloc.conf-> aj, and the program terminates in 3 seconds because it 
> does not zero the memory.
> So pick and choose the behaviour you want.

Sure, the question is if this is the result of 'X' or something else :)


Peter Pentchev	roam at    roam at    roam at
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