diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 5 | ||||
| -rw-r--r-- | kernel/exit.c | 12 |
2 files changed, 13 insertions, 4 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 13932abde15..a0123d75ec9 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2738,14 +2738,15 @@ void cgroup_fork_callbacks(struct task_struct *child) */ void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new) { - struct cgroup *oldcgrp, *newcgrp; + struct cgroup *oldcgrp, *newcgrp = NULL; if (need_mm_owner_callback) { int i; for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; oldcgrp = task_cgroup(old, ss->subsys_id); - newcgrp = task_cgroup(new, ss->subsys_id); + if (new) + newcgrp = task_cgroup(new, ss->subsys_id); if (oldcgrp == newcgrp) continue; if (ss->mm_owner_changed) diff --git a/kernel/exit.c b/kernel/exit.c index 16395644a98..85a83c83185 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -583,8 +583,6 @@ mm_need_new_owner(struct mm_struct *mm, struct task_struct *p) * If there are other users of the mm and the owner (us) is exiting * we need to find a new owner to take on the responsibility. */ - if (!mm) - return 0; if (atomic_read(&mm->mm_users) <= 1) return 0; if (mm->owner != p) @@ -627,6 +625,16 @@ retry: } while_each_thread(g, c); read_unlock(&tasklist_lock); + /* + * We found no owner yet mm_users > 1: this implies that we are + * most likely racing with swapoff (try_to_unuse()) or /proc or + * ptrace or page migration (get_task_mm()). Mark owner as NULL, + * so that subsystems can understand the callback and take action. + */ + down_write(&mm->mmap_sem); + cgroup_mm_owner_callbacks(mm->owner, NULL); + mm->owner = NULL; + up_write(&mm->mmap_sem); return; assign_new_owner: |