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authorCyrill Gorcunov <gorcunov@gmail.com>2013-09-11 14:22:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:57:56 -0700
commitd9104d1ca9662498339c0de975b4666c30485f4e (patch)
treecb95c72dde19930ca985b9834d604958ef4eecde /fs/exec.c
parent3b11f0aaae830f0f569cb8fb7fd26f4133ebdabd (diff)
downloadlinux-d9104d1ca9662498339c0de975b4666c30485f4e.tar.gz
mm: track vma changes with VM_SOFTDIRTY bit
Pavel reported that in case if vma area get unmapped and then mapped (or expanded) in-place, the soft dirty tracker won't be able to recognize this situation since it works on pte level and ptes are get zapped on unmap, loosing soft dirty bit of course. So to resolve this situation we need to track actions on vma level, there VM_SOFTDIRTY flag comes in. When new vma area created (or old expanded) we set this bit, and keep it here until application calls for clearing soft dirty bit. Thus when user space application track memory changes now it can detect if vma area is renewed. Reported-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Rob Landley <rob@landley.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/exec.c b/fs/exec.c
index fd774c7cb48..2d1e52a58fe 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -266,7 +266,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
vma->vm_end = STACK_TOP_MAX;
vma->vm_start = vma->vm_end - PAGE_SIZE;
- vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
+ vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
INIT_LIST_HEAD(&vma->anon_vma_chain);