diff options
| -rw-r--r-- | mm/memcontrol.c | 43 |
1 files changed, 26 insertions, 17 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 9be3cf8a5da4..e6aadd65a71a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -269,13 +269,14 @@ enum move_type { /* "mc" and its members are protected by cgroup_mutex */ static struct move_charge_struct { - spinlock_t lock; /* for from, to, moving_task */ + spinlock_t lock; /* for from, to */ struct mem_cgroup *from; struct mem_cgroup *to; unsigned long precharge; unsigned long moved_charge; unsigned long moved_swap; struct task_struct *moving_task; /* a task moving charges */ + struct mm_struct *mm; wait_queue_head_t waitq; /* a waitq for other context */ } mc = { .lock = __SPIN_LOCK_UNLOCKED(mc.lock), @@ -4445,7 +4446,7 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) unsigned long precharge; struct vm_area_struct *vma; - down_read(&mm->mmap_sem); + /* We've already held the mmap_sem */ for (vma = mm->mmap; vma; vma = vma->vm_next) { struct mm_walk mem_cgroup_count_precharge_walk = { .pmd_entry = mem_cgroup_count_precharge_pte_range, @@ -4457,7 +4458,6 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) walk_page_range(vma->vm_start, vma->vm_end, &mem_cgroup_count_precharge_walk); } - up_read(&mm->mmap_sem); precharge = mc.precharge; mc.precharge = 0; @@ -4508,11 +4508,16 @@ static void mem_cgroup_clear_mc(void) mc.moved_swap = 0; } + if (mc.mm) { + up_read(&mc.mm->mmap_sem); + mmput(mc.mm); + } spin_lock(&mc.lock); mc.from = NULL; mc.to = NULL; - mc.moving_task = NULL; spin_unlock(&mc.lock); + mc.moving_task = NULL; + mc.mm = NULL; memcg_oom_recover(from); memcg_oom_recover(to); wake_up_all(&mc.waitq); @@ -4537,26 +4542,37 @@ static int mem_cgroup_can_attach(struct cgroup_subsys *ss, return 0; /* We move charges only when we move a owner of the mm */ if (mm->owner == p) { + /* + * We do all the move charge works under one mmap_sem to + * avoid deadlock with down_write(&mmap_sem) + * -> try_charge() -> if (mc.moving_task) -> sleep. + */ + down_read(&mm->mmap_sem); + VM_BUG_ON(mc.from); VM_BUG_ON(mc.to); VM_BUG_ON(mc.precharge); VM_BUG_ON(mc.moved_charge); VM_BUG_ON(mc.moved_swap); VM_BUG_ON(mc.moving_task); + VM_BUG_ON(mc.mm); + spin_lock(&mc.lock); mc.from = from; mc.to = mem; mc.precharge = 0; mc.moved_charge = 0; mc.moved_swap = 0; - mc.moving_task = current; spin_unlock(&mc.lock); + mc.moving_task = current; + mc.mm = mm; ret = mem_cgroup_precharge_mc(mm); if (ret) mem_cgroup_clear_mc(); - } - mmput(mm); + /* We call up_read() and mmput() in clear_mc(). */ + } else + mmput(mm); } return ret; } @@ -4644,7 +4660,7 @@ static void mem_cgroup_move_charge(struct mm_struct *mm) struct vm_area_struct *vma; lru_add_drain_all(); - down_read(&mm->mmap_sem); + /* We've already held the mmap_sem */ for (vma = mm->mmap; vma; vma = vma->vm_next) { int ret; struct mm_walk mem_cgroup_move_charge_walk = { @@ -4663,7 +4679,6 @@ static void mem_cgroup_move_charge(struct mm_struct *mm) */ break; } - up_read(&mm->mmap_sem); } static void mem_cgroup_move_task(struct cgroup_subsys *ss, @@ -4672,17 +4687,11 @@ static void mem_cgroup_move_task(struct cgroup_subsys *ss, struct task_struct *p, bool threadgroup) { - struct mm_struct *mm; - - if (!mc.to) + if (!mc.mm) /* no need to move charge */ return; - mm = get_task_mm(p); - if (mm) { - mem_cgroup_move_charge(mm); - mmput(mm); - } + mem_cgroup_move_charge(mc.mm); mem_cgroup_clear_mc(); } #else /* !CONFIG_MMU */ |