Commit e20df2c6 authored Jan 31, 2018 by Matthew Wilcox Committed by Linus Torvalds Jan 31, 2018

mm: align struct page more aesthetically

Patch series "Restructure struct page", v2.

This series does not attempt any grand restructuring.  Instead, it cures
the worst of the indentitis, fixes the documentation and reduces the
ifdeffery.  The only layout change is compound_dtor and compound_order
are each reduced to one byte.

This patch (of 8):

Instead of an ifdef block at the end of the struct, which needed its own
comment, define _struct_page_alignment up at the top where it fits
nicely with the existing comment.

Link: http://lkml.kernel.org/r/20171220155552.15884-2-willy@infradead.org


Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 93144ca3

include/linux/mm_types.h

+7 −9

Original line number	Diff line number	Diff line
		@@ -39,6 +39,12 @@ struct hmm;
		* allows the use of atomic double word operations on the flags/mapping
		* and lru list pointers also.
		*/
		#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
		#define _struct_page_alignment __aligned(2 * sizeof(unsigned long))
		#else
		#define _struct_page_alignment
		#endif

		struct page {
		/* First double word block */
		unsigned long flags; /* Atomic flags, some possibly
		@@ -212,15 +218,7 @@ struct page {
		#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
		int _last_cpupid;
		#endif
		}
		/*
		* The struct page can be forced to be double word aligned so that atomic ops
		* on double words work. The SLUB allocator can make use of such a feature.
		*/
		#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
		__aligned(2 * sizeof(unsigned long))
		#endif
		;
		} _struct_page_alignment;

		#define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK)
		#define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE)

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