Voici une remarque du man de malloc :

By default, Linux follows an optimistic memory allocation strategy. This means that when malloc() returns non-NULL there is no guarantee that the memory really is available. This is a really bad bug. In case it turns out that the system is out of memory, one or more processes will be killed by the infamous OOM killer. In case Linux is employed under circumstances where it would be less desirable to suddenly lose some randomly picked processes, and moreover the kernel version is sufficiently recent, one can switch off this overcommitting behavior using a command like

# echo 2 > /proc/sys/vm/overcommit_memory

On dirait qu'il y a une petite guerre entre les concepteurs du noyau et les programmeurs d'applications