diff --git a/src/backend/storage/buffer/README b/src/backend/storage/buffer/README
new file mode 100644
index 45c5c83..05614d3
*** a/src/backend/storage/buffer/README
--- b/src/backend/storage/buffer/README
*************** it won't be able to actually examine the
*** 81,98 ****
  or exclusive content lock.
  
  
! Rule #5 only affects VACUUM operations.  Obtaining the
! necessary lock is done by the bufmgr routine LockBufferForCleanup().
! It first gets an exclusive lock and then checks to see if the shared pin
! count is currently 1.  If not, it releases the exclusive lock (but not the
! caller's pin) and waits until signaled by another backend, whereupon it
! tries again.  The signal will occur when UnpinBuffer decrements the shared
! pin count to 1.  As indicated above, this operation might have to wait a
! good while before it acquires lock, but that shouldn't matter much for
! concurrent VACUUM.  The current implementation only supports a single
! waiter for pin-count-1 on any particular shared buffer.  This is enough
! for VACUUM's use, since we don't allow multiple VACUUMs concurrently on a
! single relation anyway.
  
  
  Buffer Manager's Internal Locking
--- 81,101 ----
  or exclusive content lock.
  
  
! Obtaining the necessary lock is done by the bufmgr routines 
! LockBufferForCleanup() or ConditionalLockBufferForCleanup().
! They first get an exclusive lock and then check to see if the shared pin
! count is currently 1.  If not, ConditionalLockBufferForCleanup() releases
! the exclusive lock and then returns false, while LockBufferForCleanup() 
! releases the exclusive lock (but not the caller's pin) and waits until 
! signaled by another backend, whereupon it tries again.  The signal will 
! occur when UnpinBuffer decrements the shared pin count to 1.  As 
! indicated above, this operation might have to wait a good while before 
! it acquires lock, but that shouldn't matter much for concurrent VACUUM.
! The current implementation only supports a single waiter for pin-count-1 
! on any particular shared buffer.  This is enough for VACUUM's use, since 
! we don't allow multiple VACUUMs concurrently on a single relation anyway.
! Anyone wishing to obtain a clean up lock outside of a VACUUM must use
! the conditional variant of the function.
  
  
  Buffer Manager's Internal Locking