mm: kill vma flag VM_RESERVED and mm->reserved_vm counter

A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:

 | effect                 | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump      | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock           | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP

This patch removes reserved_vm counter from mm_struct.  Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.

Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.

remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.

[[email protected]: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Carsten Otte <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Cyrill Gorcunov <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Morris <[email protected]>
Cc: Jason Baron <[email protected]>
Cc: Kentaro Takeda <[email protected]>
Cc: Matt Helsley <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Robert Richter <[email protected]>
Cc: Suresh Siddha <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Venkatesh Pallipadi <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

3 files changed, 2 insertions, 4 deletions

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 95b738c7abff..ba7a0ff19d39 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -239,7 +239,7 @@ extern int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol,
 /* Check if a vma is migratable */
 static inline int vma_migratable(struct vm_area_struct *vma)
 {
-	if (vma->vm_flags & (VM_IO|VM_HUGETLB|VM_PFNMAP|VM_RESERVED))
+	if (vma->vm_flags & (VM_IO | VM_HUGETLB | VM_PFNMAP))
 		return 0;
 	/*
 	 * Migration allocates pages in the highest zone. If we cannot
diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc08d558e058..0514fe9d3c84 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -96,7 +96,6 @@ extern unsigned int kobjsize(const void *objp);
 
 #define VM_DONTCOPY	0x00020000      /* Do not copy this vma on fork */
 #define VM_DONTEXPAND	0x00040000	/* Cannot expand with mremap() */
-#define VM_RESERVED	0x00080000	/* Count as reserved_vm like IO */
 #define VM_ACCOUNT	0x00100000	/* Is a VM accounted object */
 #define VM_NORESERVE	0x00200000	/* should the VM suppress accounting */
 #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
@@ -148,7 +147,7 @@ extern unsigned int kobjsize(const void *objp);
  * Special vmas that are non-mergable, non-mlock()able.
  * Note: mm/huge_memory.c VM_NO_THP depends on this definition.
  */
-#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
+#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP)
 
 /*
  * mapping from the currently active vm_flags protection bits (the
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 58d3173eb365..a57a43f5ca7c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -349,7 +349,6 @@ struct mm_struct {
 	unsigned long shared_vm;	/* Shared pages (files) */
 	unsigned long exec_vm;		/* VM_EXEC & ~VM_WRITE */
 	unsigned long stack_vm;		/* VM_GROWSUP/DOWN */
-	unsigned long reserved_vm;	/* VM_RESERVED|VM_IO pages */
 	unsigned long def_flags;
 	unsigned long nr_ptes;		/* Page table pages */
 	unsigned long start_code, end_code, start_data, end_data;