[PATCH 0/6] Constify struct page arguments

[PATCH 0/6] Constify struct page arguments

[Matthew Wilcox (Oracle)]

While working on various solutions to the 32-bit struct page size
regression, one of the problems I found was the networking stack expects
to be able to pass const struct page pointers around, and the mm doesn't
provide a lot of const-friendly functions to call.  The root tangle of
problems is that a lot of functions call VM_BUG_ON_PAGE(), which calls
dump_page(), which calls a lot of functions which don't take a const
struct page (but could be const).

I have other things I need to work on, but I offer these patches as a few
steps towards being able to make dump_page() take a const page pointer.

Matthew Wilcox (Oracle) (6):
  mm: Make __dump_page static
  mm/debug: Factor PagePoisoned out of __dump_page
  mm/page_owner: Constify dump_page_owner
  mm: Make compound_head const-preserving
  mm: Constify get_pfnblock_flags_mask and get_pfnblock_migratetype
  mm: Constify page_count and page_ref_count

 include/linux/mmdebug.h         |  3 +--
 include/linux/page-flags.h      | 10 +++++-----
 include/linux/page_owner.h      |  6 +++---
 include/linux/page_ref.h        |  4 ++--
 include/linux/pageblock-flags.h |  2 +-
 mm/debug.c                      | 25 +++++++------------------
 mm/page_alloc.c                 | 16 ++++++++--------
 mm/page_owner.c                 |  2 +-
 8 files changed, 28 insertions(+), 40 deletions(-)

-- 
2.30.2

[PATCH 1/6] mm: Make __dump_page static

[Matthew Wilcox (Oracle)]

The only caller of __dump_page() now opencodes dump_page(), so
remove it as an externally visible symbol.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mmdebug.h | 3 +--
 mm/debug.c              | 2 +-
 mm/page_alloc.c         | 3 +--
 3 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 5d0767cb424a..1935d4c72d10 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -9,8 +9,7 @@ struct page;
 struct vm_area_struct;
 struct mm_struct;
 
-extern void dump_page(struct page *page, const char *reason);
-extern void __dump_page(struct page *page, const char *reason);
+void dump_page(struct page *page, const char *reason);
 void dump_vma(const struct vm_area_struct *vma);
 void dump_mm(const struct mm_struct *mm);
 
diff --git a/mm/debug.c b/mm/debug.c
index 0bdda8407f71..84cdcd0f7bd3 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -42,7 +42,7 @@ const struct trace_print_flags vmaflag_names[] = {
 	{0, NULL}
 };
 
-void __dump_page(struct page *page, const char *reason)
+static void __dump_page(struct page *page, const char *reason)
 {
 	struct page *head = compound_head(page);
 	struct address_space *mapping;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5a35f21b57c6..0152670c6f04 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -658,8 +658,7 @@ static void bad_page(struct page *page, const char *reason)
 
 	pr_alert("BUG: Bad page state in process %s  pfn:%05lx\n",
 		current->comm, page_to_pfn(page));
-	__dump_page(page, reason);
-	dump_page_owner(page);
+	dump_page(page, reason);
 
 	print_modules();
 	dump_stack();
-- 
2.30.2