Lockdep: Print more info in the "unbalanced unlock" case.

This CL does the following:

- Add the ability for nested locks to have names.
- Give names to all current uses of nested locks in the codebase.
- Truncate `lockdep` debug stack traces to avoid the clutter from the
  `lockdep` code itself
- Simplify `lockdep` to not longer require `classMap`.

PiperOrigin-RevId: 491486620

pkg/sentry/kernel/auth/BUILD

@@ -1,5 +1,6 @@
 load("//tools:defs.bzl", "go_library")
 load("//tools/go_generics:defs.bzl", "go_template_instance")
+load("//pkg/sync/locking:locking.bzl", "declare_mutex")
 
 package(licenses = ["notice"])
 
@@ -42,15 +43,12 @@ go_template_instance(
     },
 )
 
-go_template_instance(
+declare_mutex(
     name = "user_namespace_mutex",
     out = "user_namespace_mutex.go",
+    nested_lock_names = ["ns"],
     package = "auth",
     prefix = "userNamespace",
-    substrs = {
-        "genericMark": "userNamespace",
-    },
-    template = "//pkg/sync/locking:generic_mutex",
 )
 
 go_library(

pkg/sentry/kernel/auth/id_map.go

@@ -69,8 +69,8 @@ func (ns *UserNamespace) mapID(m *idMapSet, id uint32) uint32 {
 //
 // Preconditions: end >= start.
 func (ns *UserNamespace) allIDsMapped(m *idMapSet, start, end uint32) bool {
-	ns.mu.NestedLock()
-	defer ns.mu.NestedUnlock()
+	ns.mu.NestedLock(userNamespaceLockNs)
+	defer ns.mu.NestedUnlock(userNamespaceLockNs)
 	return m.SpanRange(idMapRange{start, end}) == end-start
 }