linux-kernel - [PATCH] Add a new vm flag to track full pfnmap at mmap

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Date:	Fri, 13 Mar 2009 16:35:44 -0700
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	"mingo@...hat.com" <mingo@...hat.com>,
	"hpa@...or.com" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	"elendil@...net.nl" <elendil@...net.nl>,
	"thellstrom@...are.com" <thellstrom@...are.com>,
	"ebiederm@...ssion.com" <ebiederm@...ssion.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...e.hu" <mingo@...e.hu>
Subject: [PATCH] Add a new vm flag to track full pfnmap at mmap


Add a new vm flag VM_PFN_AT_MMAP to identify a PFNMAP that is
fully mapped with remap_pfn_range. Patch removes the overloading
of VM_INSERTPAGE from the earlier patch.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
---
 include/linux/mm.h |   16 +++-------------
 mm/memory.c        |    4 ++--
 2 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3daa05f..b1ea37f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -98,12 +98,13 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
 #define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */
 #define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */
-#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it. Refer note in VM_PFNMAP_AT_MMAP below */
+#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */
 #define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */
 
 #define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */
 #define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */
 #define VM_SAO		0x20000000	/* Strong Access Ordering (powerpc) */
+#define VM_PFN_AT_MMAP	0x40000000	/* PFNMAP vma that is fully mapped at mmap time */
 
 #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -127,17 +128,6 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
 
 /*
- * pfnmap vmas that are fully mapped at mmap time (not mapped on fault).
- * Used by x86 PAT to identify such PFNMAP mappings and optimize their handling.
- * Note VM_INSERTPAGE flag is overloaded here. i.e,
- * VM_INSERTPAGE && !VM_PFNMAP implies
- *     The vma has had "vm_insert_page()" done on it
- * VM_INSERTPAGE && VM_PFNMAP implies
- *     The vma is PFNMAP with full mapping at mmap time
- */
-#define VM_PFNMAP_AT_MMAP (VM_INSERTPAGE | VM_PFNMAP)
-
-/*
  * mapping from the currently active vm_flags protection bits (the
  * low four bits) to a page protection mask..
  */
@@ -156,7 +146,7 @@ extern pgprot_t protection_map[16];
  */
 static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)
 {
-	return ((vma->vm_flags & VM_PFNMAP_AT_MMAP) == VM_PFNMAP_AT_MMAP);
+	return (vma->vm_flags & VM_PFN_AT_MMAP);
 }
 
 static inline int is_pfn_mapping(struct vm_area_struct *vma)
diff --git a/mm/memory.c b/mm/memory.c
index e6aced9..302591f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1677,7 +1677,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 	 */
 	if (addr == vma->vm_start && end == vma->vm_end) {
 		vma->vm_pgoff = pfn;
-		vma->vm_flags |= VM_PFNMAP_AT_MMAP;
+		vma->vm_flags |= VM_PFN_AT_MMAP;
 	} else if (is_cow_mapping(vma->vm_flags))
 		return -EINVAL;
 
@@ -1690,7 +1690,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
 		 * needed from higher level routine calling unmap_vmas
 		 */
 		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
-		vma->vm_flags &= ~VM_PFNMAP_AT_MMAP;
+		vma->vm_flags &= ~VM_PFN_AT_MMAP;
 		return -EINVAL;
 	}
 
-- 
1.6.0.6

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