malloc Is Not Free

malloc Is Not Free You Called malloc(64). Here's What Actually Happened. Reading time: ~13 minutes You called malloc(64) . You got a pointer back. You stored your data. You moved on. The kernel, the MMU hardware, the page table walker, and possibly the disk were all involved. Not necessarily in every malloc call — your allocator is pretty clever about batching all that work. But at some point, behind that innocent function call, something had to go talk to the operating system, the OS had to talk to the memory hardware, and the hardware had to talk to RAM. Understanding where that happens — and when — is the difference between "I wonder why this crashed" and "oh, of course it crashed." The Bug That Changed How We Allocate Picture this: a service allocates a 512MB buffer at startup, does a quick sanity check, then proceeds with the real work. It runs fine in staging. In production, under load, it OOM-kills itself hours later. The buffer was allocated. No error. The pointer was valid. Th