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Strangely, alloc checks no longer work in Linux and possibly other OSes. Because of overcommit you can have malloc give you an non-NULL result that will fail when you try to write to it.

I still include them in my code, but I don't expect they will save me.

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However, it is perfectly possible in Linux to turn overcommit off. So you still need to check (or segfault…).

malloc failure isn't just bound to running out of physical memory. It can fail because of fragmentation, with or without overcommit.

Sure, but I still have to design for random segfaults on memory writes. I guess I could write to all newly allocated pages and get a little more assurance that the allocation worked. I could still be whacked by a deduplicator, though unique writes would help.

I think when you run out of physical memory & swap, there's a bigger issue at that point. Or that's what the designers of overcommit decided.

OOM killer sends a SIGKILL. Writing to all pages will work for ensuring you actually got the memory. What a pain though.

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