doc: THP CoW fault no longer allocate THP

Since commit 3917c802 ("thp: change CoW semantics for anon-THP"),
THP CoW page fault is rewritten.  Now it just splits pmd then fallback
to base page fault, it doesn't try to allocate THP anymore.  So it is no
longer counted in THP_FAULT_ALLOC.

Remove the obsolete statement in documentation about THP CoW allocation
to avoid confusion.

Link: http://lkml.kernel.org/r/1592424895-5421-1-git-send-email-yang.shi@linux.alibaba.comSigned-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/admin-guide/cgroup-v2.rst

@@ -1356,8 +1356,8 @@ PAGE_SIZE multiple when read back.
 
 	  thp_fault_alloc
 		Number of transparent hugepages which were allocated to satisfy
-		a page fault, including COW faults. This counter is not present
-		when CONFIG_TRANSPARENT_HUGEPAGE is not set.
+		a page fault. This counter is not present when CONFIG_TRANSPARENT_HUGEPAGE
+                is not set.
 
 	  thp_collapse_alloc
 		Number of transparent hugepages which were allocated to allow

Documentation/admin-guide/mm/transhuge.rst

@@ -305,8 +305,7 @@ monitor how successfully the system is providing huge pages for use.
 
 thp_fault_alloc
 	is incremented every time a huge page is successfully
-	allocated to handle a page fault. This applies to both the
-	first time a page is faulted and for COW faults.
+	allocated to handle a page fault.
 
 thp_collapse_alloc
 	is incremented by khugepaged when it has found