Many security mitigations have been merged into the kernel for a long time, probably longer than grsecurity has been around, but certainly something like NX-bit

Many security mitigations have been merged into the kernel for a long time, probably longer than grsecurity has been around, but certainly something like NX-bit you could use as an example which was around the same time as early grsec (early 2000s). Sure Linus has been hostile or funny about such things at times, but that has not prevented him from being convinced or them from being merged.