Revert "mm: correctly synchronize rss-counters at exit/exec"

This reverts commit 40af1bbdca47e5c8a2044039bb78ca8fd8b20f94.

It's horribly and utterly broken for at least the following reasons:

 - calling sync_mm_rss() from mmput() is fundamentally wrong, because
   there's absolutely no reason to believe that the task that does the
   mmput() always does it on its own VM.  Example: fork, ptrace, /proc -
   you name it.

 - calling it *after* having done mmdrop() on it is doubly insane, since
   the mm struct may well be gone now.

 - testing mm against NULL before you call it is insane too, since a
NULL mm there would have caused oopses long before.

.. and those are just the three bugs I found before I decided to give up
looking for me and revert it asap.  I should have caught it before I
even took it, but I trusted Andrew too much.

Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/exec.c b/fs/exec.c
index b926ed19301e..a79786a8d2c8 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -819,6 +819,7 @@ static int exec_mmap(struct mm_struct *mm)
 	/* Notify parent that we're no longer interested in the old VM */
 	tsk = current;
 	old_mm = current->mm;
+	sync_mm_rss(old_mm);
 	mm_release(tsk, old_mm);
 
 	if (old_mm) {