mm_for_maps: shift down_read(mmap_sem) to the caller
mm_for_maps() takes ->mmap_sem after security checks, this looks
strange and obfuscates the locking rules. Move this lock to its
single caller, m_start().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 6f61b7c..9bd8be1 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -119,6 +119,7 @@
mm = mm_for_maps(priv->task);
if (!mm)
return NULL;
+ down_read(&mm->mmap_sem);
tail_vma = get_gate_vma(priv->task);
priv->tail_vma = tail_vma;