There is a call to sbrk() in sqAllocateMemory() but there is another call to sbrk() in allocateJITMemory(). So there are multiple calls to sbrk() in platforms/unix/vm/sqUnixSpurMemory.c. The pull request #672 adds an alignment calculation to the return value of sbrk() in allocateJITMemory() so to mirror the calculation in sqAllocateMemory(). The OpenGroup manpage on sbrk() says that it is unspecified whether the pointer returned by sbrk() is aligned suitably for any purpose (see https://pubs.opengroup.org/onlinepubs/7908799/xsh/brk.html).