runtime: "fatal: morestack on g0" on amd64 after upgrade to Go 1.21 [1.21 backport]

[gopherbot]

@prattmic requested issue #62440 to be considered for backport to the next 1.21 minor release.

@gopherbot please backport to 1.21. This is a fatal crash with no workaround for applications using C coroutine libraries and calling into Go. The fix here is fairly complex, so this is a medium+ risk backport, but we don't have a simpler workaround to backport. That said, the fix has baked in post-submit for 2+ weeks without further issue.

[gopherbot]

Change https://go.dev/cl/530480 mentions this issue: [release-branch.go1.21] runtime: allow update of system stack bounds on callback from C thread

[heschi]

What's the status on this one? We were waiting for any bugs to shake out on tip, I believe?