Messages in this thread | | | Date | Tue, 18 Dec 2007 22:19:22 +0000 (GMT) | From | Hugh Dickins <> | Subject | [PATCH 0/2] memcgroup: work better with tmpfs |
| |
Here's a couple of patches to get memcgroups working better with tmpfs and shmem, in conjunction with the tmpfs patches I just posted. There will be another to come later on, but I shouldn't wait any longer to get these out to you.
(The missing patch will want to leave a mem_cgroup associated with a tmpfs file or shm object, so that if its pages get brought back from swap by swapoff, they can be associated with that mem_cgroup rather than the one which happens to be running swapoff.)
mm/memcontrol.c | 81 ++++++++++++++++++++-------------------------- mm/shmem.c | 28 +++++++++++++++ 2 files changed, 63 insertions(+), 46 deletions(-)
But on the way I've noticed a number of issues with memcgroups not dealt with in these patches.
1. Why is spin_lock_irqsave rather than spin_lock needed on mz->lru_lock? If it is needed, doesn't mem_cgroup_isolate_pages need to use it too?
2. There's mem_cgroup_charge and mem_cgroup_cache_charge (wouldn't the former be better called mem_cgroup_charge_mapped? why does the latter test MEM_CGROUP_TYPE_ALL instead of MEM_CGROUP_TYPE_CACHED? I still don't understand your enums there). But there's only mem_cgroup_uncharge. So when, for example, an add_to_page_cache fails, the uncharge may not balance the charge?
3. mem_cgroup_charge_common has rcu_read_lock/unlock around its rcu_dereference; mem_cgroup_cache_charge does not: is that right?
4. That page_assign_page_cgroup in free_hot_cold_page, what case is that handling? Wouldn't there be a leak if it ever happens? I've been running with a BUG_ON(page->page_cgroup) there and not hit it - should it perhaps be a "Bad page state" case?
Hugh
| |