[RFC PATCH 08/13] kernel/fork: Define explicitly which mm_struct to duplicate during fork

Till Smejkal
2017-03-13T22:14:10Z

The dup_mm-function used during 'do_fork' to duplicate the current task's
mm_struct for the newly forked task always implicitly uses current->mm for
this purpose. However, during copy_mm it was already decided which
mm_struct to copy/duplicate. So pass this mm_struct to dup_mm instead of
again deciding which mm_struct to use.

Signed-off-by: Till Smejkal <till.smejkal@gmail.com>
---
kernel/fork.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 9209f6d5d7c0..d3087d870855 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1158,9 +1158,10 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
* Allocate a new mm structure and copy contents from the
* mm structure of the passed in task structure.
*/
-static struct mm_struct *dup_mm(struct task_struct *tsk)
+static struct mm_struct *dup_mm(struct task_struct *tsk,
+ struct mm_struct *oldmm)
{
- struct mm_struct *mm, *oldmm = current->mm;
+ struct mm_struct *mm;
int err;

mm = allocate_mm();
@@ -1226,7 +1227,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
}

retval = -ENOMEM;
- mm = dup_mm(tsk);
+ mm = dup_mm(tsk, oldmm);
if (!mm)
goto fail_nomem;

--
2.12.0