+ mm-define-pte_index-as-macro-for-x86.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm: define pte_index as macro for x86
has been added to the -mm tree.  Its filename is
     mm-define-pte_index-as-macro-for-x86.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-define-pte_index-as-macro-for-x86.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-define-pte_index-as-macro-for-x86.patch

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------------------------------------------------------
From: Arjun Roy <arjunroy@google.com>
Subject: mm: define pte_index as macro for x86

pte_index() is either defined as a macro (e.g.  sparc64) or as an inlined
function (e.g.  x86).  vm_insert_pages() depends on pte_index but it is
not defined on all platforms (e.g.  m68k).

To fix compilation of vm_insert_pages() on architectures not providing
pte_index(), we perform the following fix:

0. For platforms where it is meaningful, and defined as a macro, no
    change is needed.
1. For platforms where it is meaningful and defined as an inlined
    function, and we want to use it with vm_insert_pages(), we define
    a degenerate macro of the form:  #define pte_index pte_index
2. vm_insert_pages() checks for the existence of a pte_index macro
   definition. If found, it implements a batched insert. If not found,
   it devolves to calling vm_insert_page() in a loop.

This patch implements step 1 for x86.

v3 of this patch fixes a compilation warning for an unused method.
v2 of this patch moved a macro definition to a more readable location.

Link: http://lkml.kernel.org/r/20200228054714.204424-1-arjunroy.kdev@gmail.com
Signed-off-by: Arjun Roy <arjunroy@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/include/asm/pgtable.h |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/x86/include/asm/pgtable.h~mm-define-pte_index-as-macro-for-x86
+++ a/arch/x86/include/asm/pgtable.h
@@ -828,7 +828,10 @@ static inline unsigned long pmd_index(un
  *
  * this function returns the index of the entry in the pte page which would
  * control the given virtual address
+ *
+ * Also define macro so we can test if pte_index is defined for arch.
  */
+#define pte_index pte_index
 static inline unsigned long pte_index(unsigned long address)
 {
 	return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
_

Patches currently in -mm which might be from arjunroy@google.com are

mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
mm-bring-sparc-pte_index-semantics-inline-with-other-platforms.patch
mm-define-pte_index-as-macro-for-x86.patch
mm-add-vm_insert_pages.patch
mm-add-vm_insert_pages-2.patch
mm-add-vm_insert_pages-2-fix.patch
net-zerocopy-use-vm_insert_pages-for-tcp-rcv-zerocopy.patch