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2013-07-31vmpressure: make sure there are no events queued after memcg is offlinedMichal Hocko
vmpressure is called synchronously from reclaim where the target_memcg is guaranteed to be alive but the eventfd is signaled from the work queue context. This means that memcg (along with vmpressure structure which is embedded into it) might go away while the work item is pending which would result in use-after-release bug. We have two possible ways how to fix this. Either vmpressure pins memcg before it schedules vmpr->work and unpin it in vmpressure_work_fn or explicitely flush the work item from the css_offline context (as suggested by Tejun). This patch implements the later one and it introduces vmpressure_cleanup which flushes the vmpressure work queue item item. It hooks into mem_cgroup_css_offline after the memcg itself is cleaned up. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Tejun Heo <tj@kernel.org> Cc: Anton Vorontsov <anton.vorontsov@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Li Zefan <lizefan@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-14kernel: delete __cpuinit usage from all core kernel filesPaul Gortmaker
The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the uses of the __cpuinit macros from C files in the core kernel directories (kernel, init, lib, mm, and include) that don't really have a specific maintainer. [1] https://lkml.org/lkml/2013/5/20/589 Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-09memcg: don't need to free memcg via RCU or workqueueLi Zefan
Now memcg has the same life cycle with its corresponding cgroup, and a cgroup is freed via RCU and then mem_cgroup_css_free() will be called in a work function, so we can simply call __mem_cgroup_free() in mem_cgroup_css_free(). This actually reverts commit 59927fb984d ("memcg: free mem_cgroup by RCU to fix oops"). Signed-off-by: Li Zefan <lizefan@huawei.com> Cc: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: kill memcg refcntLi Zefan
Now memcg has the same life cycle as its corresponding cgroup. Kill the useless refcnt. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: don't need to get a reference to the parentLi Zefan
The cgroup core guarantees it's always safe to access the parent. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: use css_get/put for swap memcgLi Zefan
Use css_get/put instead of mem_cgroup_get/put. A simple replacement will do. The historical reason that memcg has its own refcnt instead of always using css_get/put, is that cgroup couldn't be removed if there're still css refs, so css refs can't be used as long-lived reference. The situation has changed so that rmdir a cgroup will succeed regardless css refs, but won't be freed until css refs goes down to 0. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: use css_get/put when charging/uncharging kmemLi Zefan
Use css_get/put instead of mem_cgroup_get/put. We can't do a simple replacement, because here mem_cgroup_put() is called during mem_cgroup_css_free(), while mem_cgroup_css_free() won't be called until css refcnt goes down to 0. Instead we increment css refcnt in mem_cgroup_css_offline(), and then check if there's still kmem charges. If not, css refcnt will be decremented immediately, otherwise the refcnt will be released after the last kmem allocation is uncahred. [akpm@linux-foundation.org: tweak comment] Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: don't use mem_cgroup_get() when creating a kmemcg cacheLi Zefan
Use css_get()/css_put() instead of mem_cgroup_get()/mem_cgroup_put(). There are two things being done in the current code: First, we acquired a css_ref to make sure that the underlying cgroup would not go away. That is a short lived reference, and it is put as soon as the cache is created. At this point, we acquire a long-lived per-cache memcg reference count to guarantee that the memcg will still be alive. so it is: enqueue: css_get create : memcg_get, css_put destroy: memcg_put So we only need to get rid of the memcg_get, change the memcg_put to css_put, and get rid of the now extra css_put. (This changelog is mostly written by Glauber) Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: use css_get() in sock_update_memcg()Li Zefan
Use css_get/css_put instead of mem_cgroup_get/put. Note, if at the same time someone is moving @current to a different cgroup and removing the old cgroup, css_tryget() may return false, and sock->sk_cgrp won't be initialized, which is fine. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg, kmem: fix reference count handling on the error pathMichal Hocko
mem_cgroup_css_online calls mem_cgroup_put if memcg_init_kmem fails. This is not correct because only memcg_propagate_kmem takes an additional reference while mem_cgroup_sockets_init is allowed to fail as well (although no current implementation fails) but it doesn't take any reference. This all suggests that it should be memcg_propagate_kmem that should clean up after itself so this patch moves mem_cgroup_put over there. Unfortunately this is not that easy (as pointed out by Li Zefan) because memcg_kmem_mark_dead marks the group dead (KMEM_ACCOUNTED_DEAD) if it is marked active (KMEM_ACCOUNTED_ACTIVE) which is the case even if memcg_propagate_kmem fails so the additional reference is dropped in that case in kmem_cgroup_destroy which means that the reference would be dropped two times. The easiest way then would be to simply remove mem_cgrroup_put from mem_cgroup_css_online and rely on kmem_cgroup_destroy doing the right thing. Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [3.8] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09Revert "memcg: avoid dangling reference count in creation failure"Michal Hocko
This reverts commit e4715f01be697a. mem_cgroup_put is hierarchy aware so mem_cgroup_put(memcg) already drops an additional reference from all parents so the additional mem_cgrroup_put(parent) potentially causes use-after-free. Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [3.9+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09memcg: do not account memory used for cache creationGlauber Costa
The memory we used to hold the memcg arrays is currently accounted to the current memcg. But that creates a problem, because that memory can only be freed after the last user is gone. Our only way to know which is the last user, is to hook up to freeing time, but the fact that we still have some in flight kmallocs will prevent freeing to happen. I believe therefore to be just easier to account this memory as global overhead. Signed-off-by: Glauber Costa <glommer@openvz.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> 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>
2013-07-09memcg: also test for skip accounting at the page allocation levelGlauber Costa
The memory we used to hold the memcg arrays is currently accounted to the current memcg. But that creates a problem, because that memory can only be freed after the last user is gone. Our only way to know which is the last user, is to hook up to freeing time, but the fact that we still have some in flight kmallocs will prevent freeing to happen. I believe therefore to be just easier to account this memory as global overhead. This patch (of 2): Disabling accounting is only relevant for some specific memcg internal allocations. Therefore we would initially not have such check at memcg_kmem_newpage_charge, since direct calls to the page allocator that are marked with GFP_KMEMCG only happen outside memcg core. We are mostly concerned with cache allocations and by having this test at memcg_kmem_get_cache we are already able to relay the allocation to the root cache and bypass the memcg caches altogether. There is one exception, though: the SLUB allocator does not create large order caches, but rather service large kmallocs directly from the page allocator. Therefore, the following sequence, when backed by the SLUB allocator: memcg_stop_kmem_account(); kmalloc(<large_number>) memcg_resume_kmem_account(); would effectively ignore the fact that we should skip accounting, since it will drive us directly to this function without passing through the cache selector memcg_kmem_get_cache. Such large allocations are extremely rare but can happen, for instance, for the cache arrays. This was never a problem in practice, because we weren't skipping accounting for the cache arrays. All the allocations we were skipping were fairly small. However, the fact that we were not skipping those allocations are a problem and can prevent the memcgs from going away. As we fix that, we need to make sure that the fix will also work with the SLUB allocator. Signed-off-by: Glauber Costa <glommer@openvz.org> Reported-by: Michal Hocko <mhocko@suze.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> 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>
2013-07-09memcg: clean up memcg->nodeinfoJohannes Weiner
Remove struct mem_cgroup_lru_info and fold its single member, the variably sized nodeinfo[0], directly into struct mem_cgroup. This should make it more obvious why it has to be the last member there. Also move the comment that's above that special last member below it, so it is more visible to somebody that considers appending to the struct mem_cgroup. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@openvz.org> 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>
2013-07-03mm: memcontrol: factor out reclaim iterator loading and updatingJohannes Weiner
mem_cgroup_iter() is too hard to follow. Factor out the lockless reclaim iterator loading and updating so it's easier to follow the big picture. Also document the iterator invalidation mechanism a bit more extensively. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03mm, memcg: don't take task_lock in task_in_mem_cgroupDavid Rientjes
For processes that have detached their mm's, task_in_mem_cgroup() unnecessarily takes task_lock() when rcu_read_lock() is all that is necessary to call mem_cgroup_from_task(). While we're here, switch task_in_mem_cgroup() to return bool. Signed-off-by: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-06-12mm: memcontrol: fix lockless reclaim hierarchy iteratorJohannes Weiner
The lockless reclaim hierarchy iterator currently has a misplaced barrier that can lead to use-after-free crashes. The reclaim hierarchy iterator consist of a sequence count and a position pointer that are read and written locklessly, with memory barriers enforcing ordering. The write side sets the position pointer first, then updates the sequence count to "publish" the new position. Likewise, the read side must read the sequence count first, then the position. If the sequence count is up to date, it's guaranteed that the position is up to date as well: writer: reader: iter->position = position if iter->sequence == expected: smp_wmb() smp_rmb() iter->sequence = sequence position = iter->position However, the read side barrier is currently misplaced, which can lead to dereferencing stale position pointers that no longer point to valid memory. Fix this. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com> Cc: <stable@kernel.org> [3.10+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-06-12memcg: don't initialize kmem-cache destroying work for root cachesAndrey Vagin
struct memcg_cache_params has a union. Different parts of this union are used for root and non-root caches. A part with destroying work is used only for non-root caches. BUG: unable to handle kernel paging request at 0000000fffffffe0 IP: kmem_cache_alloc+0x41/0x1f0 Modules linked in: netlink_diag af_packet_diag udp_diag tcp_diag inet_diag unix_diag ip6table_filter ip6_tables i2c_piix4 virtio_net virtio_balloon microcode i2c_core pcspkr floppy CPU: 0 PID: 1929 Comm: lt-vzctl Tainted: G D 3.10.0-rc1+ #2 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: kmem_cache_alloc+0x41/0x1f0 Call Trace: getname_flags.part.34+0x30/0x140 getname+0x38/0x60 do_sys_open+0xc5/0x1e0 SyS_open+0x22/0x30 system_call_fastpath+0x16/0x1b Code: f4 53 48 83 ec 18 8b 05 8e 53 b7 00 4c 8b 4d 08 21 f0 a8 10 74 0d 4c 89 4d c0 e8 1b 76 4a 00 4c 8b 4d c0 e9 92 00 00 00 4d 89 f5 <4d> 8b 45 00 65 4c 03 04 25 48 cd 00 00 49 8b 50 08 4d 8b 38 49 RIP [<ffffffff8116b641>] kmem_cache_alloc+0x41/0x1f0 Signed-off-by: Andrey Vagin <avagin@openvz.org> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Glauber Costa <glommer@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: Li Zefan <lizefan@huawei.com> Cc: <stable@vger.kernel.org> [3.9.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-24mm: memcg: remove incorrect VM_BUG_ON for swap cache pages in unchargeJohannes Weiner
Commit 0c59b89c81ea ("mm: memcg: push down PageSwapCache check into uncharge entry functions") added a VM_BUG_ON() on PageSwapCache in the uncharge path after checking that page flag once, assuming that the state is stable in all paths, but this is not the case and the condition triggers in user environments. An uncharge after the last page table reference to the page goes away can race with reclaim adding the page to swap cache. Swap cache pages are usually uncharged when they are freed after swapout, from a path that also handles swap usage accounting and memcg lifetime management. However, since the last page table reference is gone and thus no references to the swap slot left, the swap slot will be freed shortly when reclaim attempts to write the page to disk. The whole swap accounting is not even necessary. So while the race condition for which this VM_BUG_ON was added is real and actually existed all along, there are no negative effects. Remove the VM_BUG_ON again. Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reported-by: Lingzhu Xiang <lxiang@redhat.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-08mm, memcg: add rss_huge stat to memory.statDavid Rientjes
This exports the amount of anonymous transparent hugepages for each memcg via the new "rss_huge" stat in memory.stat. The units are in bytes. This is helpful to determine the hugepage utilization for individual jobs on the system in comparison to rss and opportunities where MADV_HUGEPAGE may be helpful. The amount of anonymous transparent hugepages is also included in "rss" for backwards compatibility. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> 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>
2013-04-30Merge branch 'for-3.10' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - Fixes and a lot of cleanups. Locking cleanup is finally complete. cgroup_mutex is no longer exposed to individual controlelrs which used to cause nasty deadlock issues. Li fixed and cleaned up quite a bit including long standing ones like racy cgroup_path(). - device cgroup now supports proper hierarchy thanks to Aristeu. - perf_event cgroup now supports proper hierarchy. - A new mount option "__DEVEL__sane_behavior" is added. As indicated by the name, this option is to be used for development only at this point and generates a warning message when used. Unfortunately, cgroup interface currently has too many brekages and inconsistencies to implement a consistent and unified hierarchy on top. The new flag is used to collect the behavior changes which are necessary to implement consistent unified hierarchy. It's likely that this flag won't be used verbatim when it becomes ready but will be enabled implicitly along with unified hierarchy. The option currently disables some of broken behaviors in cgroup core and also .use_hierarchy switch in memcg (will be routed through -mm), which can be used to make very unusual hierarchy where nesting is partially honored. It will also be used to implement hierarchy support for blk-throttle which would be impossible otherwise without introducing a full separate set of control knobs. This is essentially versioning of interface which isn't very nice but at this point I can't see any other options which would allow keeping the interface the same while moving towards hierarchy behavior which is at least somewhat sane. The planned unified hierarchy is likely to require some level of adaptation from userland anyway, so I think it'd be best to take the chance and update the interface such that it's supportable in the long term. Maintaining the existing interface does complicate cgroup core but shouldn't put too much strain on individual controllers and I think it'd be manageable for the foreseeable future. Maybe we'll be able to drop it in a decade. Fix up conflicts (including a semantic one adding a new #include to ppc that was uncovered by header the file changes) as per Tejun. * 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (45 commits) cpuset: fix compile warning when CONFIG_SMP=n cpuset: fix cpu hotplug vs rebuild_sched_domains() race cpuset: use rebuild_sched_domains() in cpuset_hotplug_workfn() cgroup: restore the call to eventfd->poll() cgroup: fix use-after-free when umounting cgroupfs cgroup: fix broken file xattrs devcg: remove parent_cgroup. memcg: force use_hierarchy if sane_behavior cgroup: remove cgrp->top_cgroup cgroup: introduce sane_behavior mount option move cgroupfs_root to include/linux/cgroup.h cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix cgroup: make cgroup_path() not print double slashes Revert "cgroup: remove bind() method from cgroup_subsys." perf: make perf_event cgroup hierarchical cgroup: implement cgroup_is_descendant() cgroup: make sure parent won't be destroyed before its children cgroup: remove bind() method from cgroup_subsys. devcg: remove broken_hierarchy tag cgroup: remove cgroup_lock_is_held() ...
2013-04-29memcg: take reference before releasing rcu_read_lockLi Zefan
The memcg is not referenced, so it can be destroyed at anytime right after we exit rcu read section, so it's not safe to access it. To fix this, we call css_tryget() to get a reference while we're still in rcu read section. This also removes a bogus comment above __memcg_create_cache_enqueue(). Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29mm, memcg: give exiting processes access to memory reservesDavid Rientjes
A memcg may livelock when oom if the process that grabs the hierarchy's oom lock is never the first process with PF_EXITING set in the memcg's task iteration. The oom killer, both global and memcg, will defer if it finds an eligible process that is in the process of exiting and it is not being ptraced. The idea is to allow it to exit without using memory reserves before needlessly killing another process. This normally works fine except in the memcg case with a large number of threads attached to the oom memcg. In this case, the memcg oom killer only gets called for the process that grabs the hierarchy's oom lock; all others end up blocked on the memcg's oom waitqueue. Thus, if the process that grabs the hierarchy's oom lock is never the first PF_EXITING process in the memcg's task iteration, the oom killer is constantly deferred without anything making progress. The fix is to give PF_EXITING processes access to memory reserves so that we've marked them as oom killed without any iteration. This allows __mem_cgroup_try_charge() to succeed so that the process may exit. This makes the memcg oom killer exemption for TIF_MEMDIE tasks, now immediately granted for processes with pending SIGKILLs and those in the exit path, to be equivalent to what is done for the global oom killer. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: avoid accessing memcg after releasing referenceLi Zefan
This might cause a use-after-free bug. Signed-off-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: add memory.pressure_level eventsAnton Vorontsov
With this patch userland applications that want to maintain the interactivity/memory allocation cost can use the pressure level notifications. The levels are defined like this: The "low" level means that the system is reclaiming memory for new allocations. Monitoring this reclaiming activity might be useful for maintaining cache level. Upon notification, the program (typically "Activity Manager") might analyze vmstat and act in advance (i.e. prematurely shutdown unimportant services). The "medium" level means that the system is experiencing medium memory pressure, the system might be making swap, paging out active file caches, etc. Upon this event applications may decide to further analyze vmstat/zoneinfo/memcg or internal memory usage statistics and free any resources that can be easily reconstructed or re-read from a disk. The "critical" level means that the system is actively thrashing, it is about to out of memory (OOM) or even the in-kernel OOM killer is on its way to trigger. Applications should do whatever they can to help the system. It might be too late to consult with vmstat or any other statistics, so it's advisable to take an immediate action. The events are propagated upward until the event is handled, i.e. the events are not pass-through. Here is what this means: for example you have three cgroups: A->B->C. Now you set up an event listener on cgroups A, B and C, and suppose group C experiences some pressure. In this situation, only group C will receive the notification, i.e. groups A and B will not receive it. This is done to avoid excessive "broadcasting" of messages, which disturbs the system and which is especially bad if we are low on memory or thrashing. So, organize the cgroups wisely, or propagate the events manually (or, ask us to implement the pass-through events, explaining why would you need them.) Performance wise, the memory pressure notifications feature itself is lightweight and does not require much of bookkeeping, in contrast to the rest of memcg features. Unfortunately, as of current memcg implementation, pages accounting is an inseparable part and cannot be turned off. The good news is that there are some efforts[1] to improve the situation; plus, implementing the same, fully API-compatible[2] interface for CONFIG_MEMCG=n case (e.g. embedded) is also a viable option, so it will not require any changes on the userland side. [1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291 [2] http://lkml.org/lkml/2013/2/21/454 [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings] Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Glauber Costa <glommer@parallels.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Leonid Moiseichuk <leonid.moiseichuk@nokia.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29mm/memcontrol.c: remove unnecessary ;Michel Lespinasse
Just a trivial issue I stumbled on while doing something else... Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: do not check for do_swap_account in mem_cgroup_{read,write,reset}Michal Hocko
Since commit 2d11085e404f ("memcg: do not create memsw files if swap accounting is disabled") memsw files are created only if memcg swap accounting is enabled so it doesn't make any sense to check for it explicitly in mem_cgroup_read(), mem_cgroup_write() and mem_cgroup_reset(). Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: further simplify mem_cgroup_iterMichal Hocko
mem_cgroup_iter basically does two things currently. It takes care of the house keeping (reference counting, raclaim cookie) and it iterates through a hierarchy tree (by using cgroup generic tree walk). The code would be much more easier to follow if we move the iteration outside of the function (to __mem_cgrou_iter_next) so the distinction is more clear. This patch doesn't introduce any functional changes. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Ying Han <yinghan@google.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: simplify mem_cgroup_iterMichal Hocko
The current implementation of mem_cgroup_iter has to consider both css and memcg to find out whether no group has been found (css==NULL - aka the loop is completed) and that no memcg is associated with the found node (!memcg - aka css_tryget failed because the group is no longer alive). This leads to awkward tweaks like tests for css && !memcg to skip the current node. It will be much easier if we got rid off css variable altogether and only rely on memcg. In order to do that the iteration part has to skip dead nodes. This sounds natural to me and as a nice side effect we will get a simple invariant that memcg is always alive when non-NULL and all nodes have been visited otherwise. We could get rid of the surrounding while loop but keep it in for now to make review easier. It will go away in the following patch. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Ying Han <yinghan@google.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: relax memcg iter cachingMichal Hocko
Now that the per-node-zone-priority iterator caches memory cgroups rather than their css ids we have to be careful and remove them from the iterator when they are on the way out otherwise they might live for unbounded amount of time even though their group is already gone (until the global/targeted reclaim triggers the zone under priority to find out the group is dead and let it to find the final rest). We can fix this issue by relaxing rules for the last_visited memcg. Instead of taking a reference to the css before it is stored into iter->last_visited we can just store its pointer and track the number of removed groups from each memcg's subhierarchy. This number would be stored into iterator everytime when a memcg is cached. If the iter count doesn't match the curent walker root's one we will start from the root again. The group counter is incremented upwards the hierarchy every time a group is removed. The iter_lock can be dropped because racing iterators cannot leak the reference anymore as the reference count is not elevated for last_visited when it is cached. Locking rules got a bit complicated by this change though. The iterator primarily relies on rcu read lock which makes sure that once we see a valid last_visited pointer then it will be valid for the whole RCU walk. smp_rmb makes sure that dead_count is read before last_visited and last_dead_count while smp_wmb makes sure that last_visited is updated before last_dead_count so the up-to-date last_dead_count cannot point to an outdated last_visited. css_tryget then makes sure that the last_visited is still alive in case the iteration races with the cached group removal (css is invalidated before mem_cgroup_css_offline increments dead_count). In short: mem_cgroup_iter rcu_read_lock() dead_count = atomic_read(parent->dead_count) smp_rmb() if (dead_count != iter->last_dead_count) last_visited POSSIBLY INVALID -> last_visited = NULL if (!css_tryget(iter->last_visited)) last_visited DEAD -> last_visited = NULL next = find_next(last_visited) css_tryget(next) css_put(last_visited) // css would be invalidated and parent->dead_count // incremented if this was the last reference iter->last_visited = next smp_wmb() iter->last_dead_count = dead_count rcu_read_unlock() cgroup_rmdir cgroup_destroy_locked atomic_add(CSS_DEACT_BIAS, &css->refcnt) // subsequent css_tryget fail mem_cgroup_css_offline mem_cgroup_invalidate_reclaim_iterators while(parent = parent_mem_cgroup) atomic_inc(parent->dead_count) css_put(css) // last reference held by cgroup core Spotted by Ying Han. Original idea from Johannes Weiner. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: rework mem_cgroup_iter to use cgroup iteratorsMichal Hocko
mem_cgroup_iter curently relies on css->id when walking down a group hierarchy tree. This is really awkward because the tree walk depends on the groups creation ordering. The only guarantee is that a parent node is visited before its children. Example: 1) mkdir -p a a/d a/b/c 2) mkdir -a a/b/c a/d Will create the same trees but the tree walks will be different: 1) a, d, b, c 2) a, b, c, d Commit 574bd9f7c7c1 ("cgroup: implement generic child / descendant walk macros") has introduced generic cgroup tree walkers which provide either pre-order or post-order tree walk. This patch converts css->id based iteration to pre-order tree walk to keep the semantic with the original iterator where parent is always visited before its subtree. cgroup_for_each_descendant_pre suggests using post_create and pre_destroy for proper synchronization with groups addidition resp. removal. This implementation doesn't use those because a new memory cgroup is initialized sufficiently for iteration in mem_cgroup_css_alloc already and css reference counting enforces that the group is alive for both the last seen cgroup and the found one resp. it signals that the group is dead and it should be skipped. If the reclaim cookie is used we need to store the last visited group into the iterator so we have to be careful that it doesn't disappear in the mean time. Elevated reference count on the css keeps it alive even though the group have been removed (parked waiting for the last dput so that it can be freed). Per node-zone-prio iter_lock has been introduced to ensure that css_tryget and iter->last_visited is set atomically. Otherwise two racing walkers could both take a references and only one release it leading to a css leak (which pins cgroup dentry). Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Ying Han <yinghan@google.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29memcg: keep prev's css alive for the whole mem_cgroup_iterMichal Hocko
The patchset tries to make mem_cgroup_iter saner in the way how it walks hierarchies. css->id based traversal is far from being ideal as it is not deterministic because it depends on the creation ordering. Additional to that css_id is considered a burden for cgroup maintainers because it is quite some code and memcg is the last user of it. After this series only the swap accounting uses css_id but that one will follow up later. Diffstat (if we exclude removed/added comments) looks quite promising. We got rid of some code: $ git diff mmotm... | grep -v "^[+-][[:space:]]*[/ ]\*" | diffstat b/include/linux/cgroup.h | 3 --- kernel/cgroup.c | 33 --------------------------------- mm/memcontrol.c | 4 +++- 3 files changed, 3 insertions(+), 37 deletions(-) The first patch is just preparatory and it changes when we release css of the previously returned memcg. Nothing controlversial. The second patch is the core of the patchset and it replaces css_get_next based on css_id by the generic cgroup pre-order. This brings some chalanges for the last visited group caching during the reclaim (mem_cgroup_per_zone::reclaim_iter). We have to use memcg pointers directly now which means that we have to keep a reference to those groups' css to keep them alive. I also folded iter_lock introduced by https://lkml.org/lkml/2013/1/3/295 in the previous version into this patch. Johannes felt the race I was describing should be mostly harmless and I haven't been able to trigger it so the lock doesn't deserve its own patch. It is still needed temporarily, though, because the reference counting on iter->last_visited depends on it. It will go away with the next patch. The next patch fixups an unbounded cgroup removal holdoff caused by the elevated css refcount. The issue has been observed by Ying Han. Johannes wasn't impressed by the previous version of the fix (https://lkml.org/lkml/2013/2/8/379) which cleaned up pending references during mem_cgroup_css_offline when a group is removed. He has suggested a different way when the iterator checks whether a cached memcg is still valid or no. More on that in the patch but the basic idea is that every memcg tracks the number removed subgroups and iterator records this number when a group is cached. These numbers are checked before iter->last_visited is about to be used and the iteration is restarted if it is invalid. The fourth and fifth patches are an attempt for simplification of the mem_cgroup_iter. css juggling is removed and the iteration logic is moved to a helper so that the reference counting and iteration are separated. The last patch just removes css_get_next as there is no user for it any longer. My testing looked as follows: A (use_hierarchy=1, limit_in_bytes=150M) /|\ 1 2 3 Children groups were created so that the number is never higher than 3 and their limits were random between 50-100M. Each group hosts a kernel build (starting with tar -xf so the tree is not shared and make -jNUM_CPUs/3) and terminated after random time - up to 5 minutes) and then it is removed. This should exercise both leaf and hierarchical reclaim as well as races with cgroup removals and debugging messages I added on top proved that. 100 groups were created during the test. This patch: css reference counting keeps the cgroup alive even though it has been already removed. mem_cgroup_iter relies on this fact and takes a reference to the returned group. The reference is then released on the next iteration or mem_cgroup_iter_break. mem_cgroup_iter currently releases the reference right after it gets the last css_id. This is correct because neither prev's memcg nor cgroup are accessed after then. This will change in the next patch so we need to hold the group alive a bit longer so let's move the css_put at the end of the function. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Ying Han <yinghan@google.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-15memcg: force use_hierarchy if sane_behaviorTejun Heo
Turn on use_hierarchy by default if sane_behavior is specified and don't create .use_hierarchy file. It is debatable whether to remove .use_hierarchy file or make it ro as the former could make transition easier in certain cases; however, the behavior changes which will be gated by sane_behavior are intensive including changing basic meaning of certain control knobs in a few controllers and I don't really think keeping this piece would make things easier in any noticeable way, so let's remove it. v2: Explain that mem_cgroup_bind() doesn't have to worry about children as suggested by Michal Hocko. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2013-04-07memcg: fix memcg_cache_name() to use cgroup_name()Michal Hocko
As cgroup supports rename, it's unsafe to dereference dentry->d_name without proper vfs locks. Fix this by using cgroup_name() rather than dentry directly. Also open code memcg_cache_name because it is called only from kmem_cache_dup which frees the returned name right after kmem_cache_create_memcg makes a copy of it. Such a short-lived allocation doesn't make too much sense. So replace it by a static buffer as kmem_cache_dup is called with memcg_cache_mutex. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Glauber Costa <glommer@parallels.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2013-03-08memcg: initialize kmem-cache destroying work earlierKonstantin Khlebnikov
Fix a warning from lockdep caused by calling cancel_work_sync() for uninitialized struct work. This path has been triggered by destructon kmem-cache hierarchy via destroying its root kmem-cache. cache ffff88003c072d80 obj ffff88003b410000 cache ffff88003c072d80 obj ffff88003b924000 cache ffff88003c20bd40 INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. Pid: 2825, comm: insmod Tainted: G O 3.9.0-rc1-next-20130307+ #611 Call Trace: __lock_acquire+0x16a2/0x1cb0 lock_acquire+0x8a/0x120 flush_work+0x38/0x2a0 __cancel_work_timer+0x89/0xf0 cancel_work_sync+0xb/0x10 kmem_cache_destroy_memcg_children+0x81/0xb0 kmem_cache_destroy+0xf/0xe0 init_module+0xcb/0x1000 [kmem_test] do_one_initcall+0x11a/0x170 load_module+0x19b0/0x2320 SyS_init_module+0xc6/0xf0 system_call_fastpath+0x16/0x1b Example module to demonstrate: #include <linux/module.h> #include <linux/slab.h> #include <linux/mm.h> #include <linux/workqueue.h> int __init mod_init(void) { int size = 256; struct kmem_cache *cache; void *obj; struct page *page; cache = kmem_cache_create("kmem_cache_test", size, size, 0, NULL); if (!cache) return -ENOMEM; printk("cache %p\n", cache); obj = kmem_cache_alloc(cache, GFP_KERNEL); if (obj) { page = virt_to_head_page(obj); printk("obj %p cache %p\n", obj, page->slab_cache); kmem_cache_free(cache, obj); } flush_scheduled_work(); obj = kmem_cache_alloc(cache, GFP_KERNEL); if (obj) { page = virt_to_head_page(obj); printk("obj %p cache %p\n", obj, page->slab_cache); kmem_cache_free(cache, obj); } kmem_cache_destroy(cache); return -EBUSY; } module_init(mod_init); MODULE_LICENSE("GPL"); Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: stop warning on memcg_propagate_kmemHugh Dickins
Whilst I run the risk of a flogging for disloyalty to the Lord of Sealand, I do have CONFIG_MEMCG=y CONFIG_MEMCG_KMEM not set, and grow tired of the "mm/memcontrol.c:4972:12: warning: `memcg_propagate_kmem' defined but not used [-Wunused-function]" seen in 3.8-rc: move the #ifdef outwards. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Glauber Costa <glommer@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: cleanup mem_cgroup_init commentMichal Hocko
We should encourage all memcg controller initialization independent on a specific mem_cgroup to be done here rather than exploit css_alloc callback and assume that nothing happens before root cgroup is created. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <htejun@gmail.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>
2013-02-24memcg: move memcg_stock initialization to mem_cgroup_initMichal Hocko
memcg_stock are currently initialized during the root cgroup allocation which is OK but it pointlessly pollutes memcg allocation code with something that can be called when the memcg subsystem is initialized by mem_cgroup_init along with other controller specific parts. This patch wraps the current memcg_stock initialization code into a helper calls it from the controller subsystem initialization code. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <htejun@gmail.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>
2013-02-24memcg: move mem_cgroup_soft_limit_tree_init to mem_cgroup_initMichal Hocko
Per-node-zone soft limit tree is currently initialized when the root cgroup is created which is OK but it pointlessly pollutes memcg allocation code with something that can be called when the memcg subsystem is initialized by mem_cgroup_init along with other controller specific parts. While we are at it let's make mem_cgroup_soft_limit_tree_init void because it doesn't make much sense to report memory failure because if we fail to allocate memory that early during the boot then we are screwed anyway (this saves some code). Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <htejun@gmail.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>
2013-02-24mm: refactor inactive_file_is_low() to use get_lru_size()Johannes Weiner
An inactive file list is considered low when its active counterpart is bigger, regardless of whether it is a global zone LRU list or a memcg zone LRU list. The only difference is in how the LRU size is assessed. get_lru_size() does the right thing for both global and memcg reclaim situations. Get rid of inactive_file_is_low_global() and mem_cgroup_inactive_file_is_low() by using get_lru_size() and compare the numbers in common code. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: avoid dangling reference count in creation failure.Glauber Costa
When use_hierarchy is enabled, we acquire an extra reference count in our parent during cgroup creation. We don't release it, though, if any failure exist in the creation process. Signed-off-by: Glauber Costa <glommer@parallels.com> Reported-by: Michal Hocko <mhocko@suse.cz> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: increment static branch right after limit setGlauber Costa
We were deferring the kmemcg static branch increment to a later time, due to a nasty dependency between the cpu_hotplug lock, taken by the jump label update, and the cgroup_lock. Now we no longer take the cgroup lock, and we can save ourselves the trouble. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: replace cgroup_lock with memcg specific memcg_lockGlauber Costa
After the preparation work done in earlier patches, the cgroup_lock can be trivially replaced with a memcg-specific lock. This is an automatic translation at every site where the values involved were queried. The sites where values are written, however, used to be naturally called under cgroup_lock. This is the case for instance in the css_online callback. For those, we now need to explicitly add the memcg lock. With this, all the calls to cgroup_lock outside cgroup core are gone. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: fast hierarchy-aware child testGlauber Costa
Currently, we use cgroups' provided list of children to verify if it is safe to proceed with any value change that is dependent on the cgroup being empty. This is less than ideal, because it enforces a dependency over cgroup core that we would be better off without. The solution proposed here is to iterate over the child cgroups and if any is found that is already online, we bounce and return: we don't really care how many children we have, only if we have any. This is also made to be hierarchy aware. IOW, cgroups with hierarchy disabled, while they still exist, will be considered for the purpose of this interface as having no children. [akpm@linux-foundation.org: tweak comments] Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: split part of memcg creation to css_onlineGlauber Costa
This patch is a preparatory work for later locking rework to get rid of big cgroup lock from memory controller code. The memory controller uses some tunables to adjust its operation. Those tunables are inherited from parent to children upon children intialization. For most of them, the value cannot be changed after the parent has a new children. cgroup core splits initialization in two phases: css_alloc and css_online. After css_alloc, the memory allocation and basic initialization are done. But the new group is not yet visible anywhere, not even for cgroup core code. It is only somewhere between css_alloc and css_online that it is inserted into the internal children lists. Copying tunable values in css_alloc will lead to inconsistent values: the children will copy the old parent values, that can change between the copy and the moment in which the groups is linked to any data structure that can indicate the presence of children. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: prevent changes to move_charge_at_immigrate during task attachGlauber Costa
In memcg, we use the cgroup_lock basically to synchronize against attaching new children to a cgroup. We do this because we rely on cgroup core to provide us with this information. We need to guarantee that upon child creation, our tunables are consistent. For those, the calls to cgroup_lock() all live in handlers like mem_cgroup_hierarchy_write(), where we change a tunable in the group that is hierarchy-related. For instance, the use_hierarchy flag cannot be changed if the cgroup already have children. Furthermore, those values are propagated from the parent to the child when a new child is created. So if we don't lock like this, we can end up with the following situation: A B memcg_css_alloc() mem_cgroup_hierarchy_write() copy use hierarchy from parent change use hierarchy in parent finish creation. This is mainly because during create, we are still not fully connected to the css tree. So all iterators and the such that we could use, will fail to show that the group has children. My observation is that all of creation can proceed in parallel with those tasks, except value assignment. So what this patch series does is to first move all value assignment that is dependent on parent values from css_alloc to css_online, where the iterators all work, and then we lock only the value assignment. This will guarantee that parent and children always have consistent values. Together with an online test, that can be derived from the observation that the refcount of an online memcg can be made to be always positive, we should be able to synchronize our side without the cgroup lock. This patch: Currently, we rely on the cgroup_lock() to prevent changes to move_charge_at_immigrate during task migration. However, this is only needed because the current strategy keeps checking this value throughout the whole process. Since all we need is serialization, one needs only to guarantee that whatever decision we made in the beginning of a specific migration is respected throughout the process. We can achieve this by just saving it in mc. By doing this, no kind of locking is needed. Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: reduce the size of struct memcg 244-fold.Glauber Costa
In order to maintain all the memcg bookkeeping, we need per-node descriptors, which will in turn contain a per-zone descriptor. Because we want to statically allocate those, this array ends up being very big. Part of the reason is that we allocate something large enough to hold MAX_NUMNODES, the compile time constant that holds the maximum number of nodes we would ever consider. However, we can do better in some cases if the firmware help us. This is true for modern x86 machines; coincidentally one of the architectures in which MAX_NUMNODES tends to be very big. By using the firmware-provided maximum number of nodes instead of MAX_NUMNODES, we can reduce the memory footprint of struct memcg considerably. In the extreme case in which we have only one node, this reduces the size of the structure from ~ 64k to ~2k. This is particularly important because it means that we will no longer resort to the vmalloc area for the struct memcg on defconfigs. We also have enough room for an extra node and still be outside vmalloc. One also has to keep in mind that with the industry's ability to fit more processors in a die as fast as the FED prints money, a nodes = 2 configuration is already respectably big. [akpm@linux-foundation.org: add check for invalid nid, remove inline] Signed-off-by: Glauber Costa <glommer@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ying Han <yinghan@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: clean up swap accounting initialization codeMichal Hocko
Memcg swap accounting is currently enabled by enable_swap_cgroup when the root cgroup is created. mem_cgroup_init acts as a memcg subsystem initializer which sounds like a much better place for enable_swap_cgroup as well. We already register memsw files from there so it makes a lot of sense to merge those two into a single enable_swap_cgroup function. This patch doesn't introduce any semantic changes. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Zhouping Liu <zliu@redhat.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Li Zefan <lizefan@huawei.com> Cc: CAI Qian <caiqian@redhat.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24memcg: do not create memsw files if swap accounting is disabledMichal Hocko
Zhouping Liu has reported that memsw files are exported even though swap accounting is runtime disabled if MEMCG_SWAP is enabled. This behavior has been introduced by commit af36f906c0f4 ("memcg: always create memsw files if CGROUP_MEM_RES_CTLR_SWAP") and it causes any attempt to open the file to return EOPNOTSUPP. Although EOPNOTSUPP should say be clear that memsw operations are not supported in the given configuration it is fair to say that this behavior could be quite confusing. Let's tear memsw files out of default cgroup files and add them only if the swap accounting is really enabled (either by MEMCG_SWAP_ENABLED or swapaccount=1 boot parameter). We can hook into mem_cgroup_init which is called when the memcg subsystem is initialized and which happens after boot command line is processed. Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Zhouping Liu <zliu@redhat.com> Tested-by: Zhouping Liu <zliu@redhat.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Li Zefan <lizefan@huawei.com> Cc: CAI Qian <caiqian@redhat.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-24swap: make each swap partition have one address_spaceShaohua Li
When I use several fast SSD to do swap, swapper_space.tree_lock is heavily contended. This makes each swap partition have one address_space to reduce the lock contention. There is an array of address_space for swap. The swap entry type is the index to the array. In my test with 3 SSD, this increases the swapout throughput 20%. [akpm@linux-foundation.org: revert unneeded change to __add_to_swap_cache] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>