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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2008-05-12 14:02:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-13 08:02:25 -0700
commit4cd1a8fc3d3cd740416b14ece2693dbb5d065eaf (patch)
tree2acebe40e15b91a3df78ea5b677a84c509a30ae0
parentc9bfcb3151040cff6714542d1da04ccd7e2d3efc (diff)
memcg: fix possible panic when CONFIG_MM_OWNER=y
When mm destruction happens, we should pass mm_update_next_owner() the old mm. But unfortunately new mm is passed in exec_mmap(). Thus, kernel panic is possible when a multi-threaded process uses exec(). Also, the owner member comment description is wrong. mm->owner does not necessarily point to the thread group leader. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: "Paul Menage" <menage@google.com> Cc: "KAMEZAWA Hiroyuki" <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/exec.c2
-rw-r--r--include/linux/mm_types.h13
2 files changed, 12 insertions, 3 deletions
diff --git a/fs/exec.c b/fs/exec.c
index aeaa9791d8be..1f8a24aa1f8b 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -736,7 +736,7 @@ static int exec_mmap(struct mm_struct *mm)
tsk->active_mm = mm;
activate_mm(active_mm, mm);
task_unlock(tsk);
- mm_update_next_owner(mm);
+ mm_update_next_owner(old_mm);
arch_pick_mmap_layout(mm);
if (old_mm) {
up_read(&old_mm->mmap_sem);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index eb7c16cc9559..02a27ae78539 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -226,8 +226,17 @@ struct mm_struct {
rwlock_t ioctx_list_lock; /* aio lock */
struct kioctx *ioctx_list;
#ifdef CONFIG_MM_OWNER
- struct task_struct *owner; /* The thread group leader that */
- /* owns the mm_struct. */
+ /*
+ * "owner" points to a task that is regarded as the canonical
+ * user/owner of this mm. All of the following must be true in
+ * order for it to be changed:
+ *
+ * current == mm->owner
+ * current->mm != mm
+ * new_owner->mm == mm
+ * new_owner->alloc_lock is held
+ */
+ struct task_struct *owner;
#endif
#ifdef CONFIG_PROC_FS