alt Hacker NewsThanks for the explanation. I should have looked up each term a bit more.
So "backing" is the underlying physical memory the page maps to.
So if I were to make sense of that piece of slop, is this what it would be?
"In one thread, a page fault happens during a store operation. The physical memory address is the proper address, which is immediately (around 10 assembly instructions later) replaced by the 0x00000000 memory address by another thread due to race condition, resulting in a crash when the original thread tries to read that page again."
The first thread is the user program, the other thread is the kernel doing things on another core.
Reading from the zero page is legal, that doesn’t cause it to crash. The crash is because of a logic “bug” in the program where the zero it reads back causes some other issue in the program.
I say “bug” because it’s clearly impossible without the kernel messing up. It just stored a non-zero value there.