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-rw-r--r--include/linux/cgroup.h3
-rw-r--r--kernel/cgroup.c4
-rw-r--r--kernel/exit.c9
3 files changed, 9 insertions, 7 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c98dd7c..30934e4 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -326,7 +326,8 @@ struct cgroup_subsys {
*/
void (*mm_owner_changed)(struct cgroup_subsys *ss,
struct cgroup *old,
- struct cgroup *new);
+ struct cgroup *new,
+ struct task_struct *p);
int subsys_id;
int active;
int disabled;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a0123d7..8c6e1c1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2735,6 +2735,8 @@ void cgroup_fork_callbacks(struct task_struct *child)
* Called on every change to mm->owner. mm_init_owner() does not
* invoke this routine, since it assigns the mm->owner the first time
* and does not change it.
+ *
+ * The callbacks are invoked with mmap_sem held in read mode.
*/
void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
{
@@ -2750,7 +2752,7 @@ void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
if (oldcgrp == newcgrp)
continue;
if (ss->mm_owner_changed)
- ss->mm_owner_changed(ss, oldcgrp, newcgrp);
+ ss->mm_owner_changed(ss, oldcgrp, newcgrp, new);
}
}
}
diff --git a/kernel/exit.c b/kernel/exit.c
index 85a83c8..0ef4673 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -640,24 +640,23 @@ retry:
assign_new_owner:
BUG_ON(c == p);
get_task_struct(c);
+ read_unlock(&tasklist_lock);
+ down_write(&mm->mmap_sem);
/*
* The task_lock protects c->mm from changing.
* We always want mm->owner->mm == mm
*/
task_lock(c);
- /*
- * Delay read_unlock() till we have the task_lock()
- * to ensure that c does not slip away underneath us
- */
- read_unlock(&tasklist_lock);
if (c->mm != mm) {
task_unlock(c);
+ up_write(&mm->mmap_sem);
put_task_struct(c);
goto retry;
}
cgroup_mm_owner_callbacks(mm->owner, c);
mm->owner = c;
task_unlock(c);
+ up_write(&mm->mmap_sem);
put_task_struct(c);
}
#endif /* CONFIG_MM_OWNER */
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