Merge tag 'lkmm.2023.10.28a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull Linux Kernel Memory Model updates from Paul McKenney:
 "This update adds paragraphs to the portions of memory-barriers.txt
  that have been marked historical due to changes in the way that the
  Linux kernel handles DEC Alpha. These paragraphs includes information
  on where to find the corresponding up-to-date information"

* tag 'lkmm.2023.10.28a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  docs: memory-barriers: Add note on compiler transformation and address deps

Author: torvalds

Documentation/memory-barriers.txt

@@ -396,6 +396,10 @@ Memory barriers come in four basic varieties:
 
 
  (2) Address-dependency barriers (historical).
+     [!] This section is marked as HISTORICAL: For more up-to-date
+     information, including how compiler transformations related to pointer
+     comparisons can sometimes cause problems, see
+     Documentation/RCU/rcu_dereference.rst.
 
      An address-dependency barrier is a weaker form of read barrier.  In the
      case where two loads are performed such that the second depends on the
@@ -556,6 +560,9 @@ There are certain things that the Linux kernel memory barriers do not guarantee:
 
 ADDRESS-DEPENDENCY BARRIERS (HISTORICAL)
 ----------------------------------------
+[!] This section is marked as HISTORICAL: For more up-to-date information,
+including how compiler transformations related to pointer comparisons can
+sometimes cause problems, see Documentation/RCU/rcu_dereference.rst.
 
 As of v4.15 of the Linux kernel, an smp_mb() was added to READ_ONCE() for
 DEC Alpha, which means that about the only people who need to pay attention