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.

[akpm@linux-foundation.org: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 7b1e4feaec06..e09c04813186 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2297,14 +2297,13 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
          * rest of the world about it:
          *   VM_IO tells people not to look at these pages
          *      (accesses can have side effects).
-         *   VM_RESERVED is specified all over the place, because
-         *      in 2.4 it kept swapout's vma scan off this vma; but
-         *      in 2.6 the LRU scan won't even find its pages, so this
-         *      flag means no more than count its pages in reserved_vm,
-         *      and omit it from core dump, even when VM_IO turned off.
          *   VM_PFNMAP tells the core MM that the base pages are just
          *      raw PFN mappings, and do not have a "struct page" associated
          *      with them.
+         *   VM_DONTEXPAND
+         *      Disable vma merging and expanding with mremap().
+         *   VM_DONTDUMP
+         *      Omit vma from core dump, even when VM_IO turned off.
          *
          * There's a horrible special case to handle copy-on-write
          * behaviour that some programs depend on. We mark the "original"
@@ -2321,7 +2320,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
         if (err)
                 return -EINVAL;
 
-        vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
+        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
 
         BUG_ON(addr >= end);
         pfn -= addr >> PAGE_SHIFT;