mm: prepare VM_DONTDUMP for using in drivers

Rename VM_NODUMP into VM_DONTDUMP: this name matches other negative flags:
VM_DONTEXPAND, VM_DONTCOPY.  Currently this flag used only for
sys_madvise.  The next patch will use it for replacing the outdated flag
VM_RESERVED.

Also forbid madvise(MADV_DODUMP) for special kernel mappings VM_SPECIAL
(VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)

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>

3 files changed, 8 insertions, 4 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 28a64e769527..2b72d26e2e4b 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1123,7 +1123,7 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
         if (always_dump_vma(vma))
                 goto whole;
 
-        if (vma->vm_flags & VM_NODUMP)
+        if (vma->vm_flags & VM_DONTDUMP)
                 return 0;
 
         /* Hugetlb memory check */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 25ef49c1f2bd..dc08d558e058 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -102,7 +102,7 @@ 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_ARCH_1       0x01000000      /* Architecture-specific flag */
-#define VM_NODUMP       0x04000000      /* Do not include in the core dump */
+#define VM_DONTDUMP     0x04000000      /* Do not include in the core dump */
 
 #define VM_MIXEDMAP     0x10000000      /* Can contain "struct page" and pure PFN pages */
 #define VM_HUGEPAGE     0x20000000      /* MADV_HUGEPAGE marked this vma */
diff --git a/mm/madvise.c b/mm/madvise.c
index 14d260fa0d17..03dfa5c7adb3 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -69,10 +69,14 @@ static long madvise_behavior(struct vm_area_struct * vma,
                 new_flags &= ~VM_DONTCOPY;
                 break;
         case MADV_DONTDUMP:
-                new_flags |= VM_NODUMP;
+                new_flags |= VM_DONTDUMP;
                 break;
         case MADV_DODUMP:
-                new_flags &= ~VM_NODUMP;
+                if (new_flags & VM_SPECIAL) {
+                        error = -EINVAL;
+                        goto out;
+                }
+                new_flags &= ~VM_DONTDUMP;
                 break;
         case MADV_MERGEABLE:
         case MADV_UNMERGEABLE: