[RFC PATCH 1/3] Add flags for temporary compound pages

[Alex Thorlton]

This chunk of the patch just adds the necessary page flags to support
what I call a temporary compound page.  Temporary compound pages provide
us with the ability to turn a chunk of pages into a proper THP at some
point after pulling them off the free list, but also allow us to fault
in single 4K pages from the chunk.

Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Nate Zimmer <nzimmer@xxxxxxx>
Cc: Cliff Wickman <cpw@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Benjamin LaHaise <bcrl@xxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxxxxx>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx

---
 include/linux/gfp.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 9b4dd49..6ec63dd 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -35,6 +35,7 @@ struct vm_area_struct;
 #define ___GFP_NO_KSWAPD	0x400000u
 #define ___GFP_OTHER_NODE	0x800000u
 #define ___GFP_WRITE		0x1000000u
+#define ___GFP_COMP_TEMP	0x2000000u
 /* If the above are modified, __GFP_BITS_SHIFT may need updating */
 
 /*
@@ -77,6 +78,7 @@ struct vm_area_struct;
 #define __GFP_NORETRY	((__force gfp_t)___GFP_NORETRY) /* See above */
 #define __GFP_MEMALLOC	((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves */
 #define __GFP_COMP	((__force gfp_t)___GFP_COMP)	/* Add compound page metadata */
+#define __GFP_COMP_TEMP	((__force gfp_t)___GFP_COMP_TEMP)	/* Treat as temp compound page */
 #define __GFP_ZERO	((__force gfp_t)___GFP_ZERO)	/* Return zeroed page on success */
 #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves.
 							 * This takes precedence over the
@@ -121,6 +123,9 @@ struct vm_area_struct;
 #define GFP_TRANSHUGE	(GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 			 __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | \
 			 __GFP_NO_KSWAPD)
+#define GFP_TEMP_TRANSHUGE	(GFP_HIGHUSER_MOVABLE | __GFP_COMP_TEMP | \
+				 __GFP_NOMEMALLOC | __GFP_NORETRY | \
+				 __GFP_NOWARN | __GFP_NO_KSWAPD)
 
 #ifdef CONFIG_NUMA
 #define GFP_THISNODE	(__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY)
-- 
1.7.12.4


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