mm: prepare VM_DONTDUMP for using in drivers

koct9i · torvalds · commit 0103bd16fb90 · 2012-10-09T16:22:18.000+09:00
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  The next patch will use it for replacing the outdated flag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 &lt;khlebnikov@openvz.org&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Carsten Otte &lt;cotte@de.ibm.com&gt;
Cc: Chris Metcalf &lt;cmetcalf@tilera.com&gt;
Cc: Cyrill Gorcunov &lt;gorcunov@openvz.org&gt;
Cc: Eric Paris &lt;eparis@redhat.com&gt;
Cc: H. Peter Anvin &lt;hpa@zytor.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: James Morris &lt;james.l.morris@oracle.com&gt;
Cc: Jason Baron &lt;jbaron@redhat.com&gt;
Cc: Kentaro Takeda &lt;takedakn@nttdata.co.jp&gt;
Cc: Matt Helsley &lt;matthltc@us.ibm.com&gt;
Cc: Nick Piggin &lt;npiggin@kernel.dk&gt;
Cc: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Robert Richter &lt;robert.richter@amd.com&gt;
Cc: Suresh Siddha &lt;suresh.b.siddha@intel.com&gt;
Cc: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Cc: Venkatesh Pallipadi &lt;venki@google.com&gt;
Acked-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git 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
@@ -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
@@ -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:
