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path: root/include/linux/cgroup.h
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2013-01-24cgroup: remove synchronize_rcu() from cgroup_diput()Li Zefan
Free cgroup via call_rcu(). The actual work is done through workqueue. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2013-01-07cgroup: implement cgroup_rightmost_descendant()Tejun Heo
Implement cgroup_rightmost_descendant() which returns the right most descendant of the specified cgroup. This can be used to skip the cgroup's subtree while iterating with cgroup_for_each_descendant_pre(). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com>
2013-01-07cgroup: remove unused dummy cgroup_fork_callbacks()Tejun Heo
5edee61ede ("cgroup: cgroup_subsys->fork() should be called after the task is added to css_set") removed cgroup_fork_callbacks() but forgot to remove its dummy version for !CONFIG_CGROUPS. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
2012-11-20cgroup: remove obsolete guarantee from cgroup_task_migrate.Tao Ma
'guarantee' is already removed from cgroup_task_migrate, so remove the corresponding comments. Some other typos in cgroup are also changed. Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-19cgroup: add cgroup->idTejun Heo
With the introduction of generic cgroup hierarchy iterators, css_id is being phased out. It was unnecessarily complex, id'ing the wrong thing (cgroups need IDs, not CSSes) and has other oddities like not being available at ->css_alloc(). This patch adds cgroup->id, which is a simple per-hierarchy ida-allocated ID which is assigned before ->css_alloc() and released after ->css_free(). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com>
2012-11-19cgroup, cpuset: remove cgroup_subsys->post_clone()Tejun Heo
Currently CGRP_CPUSET_CLONE_CHILDREN triggers ->post_clone(). Now that clone_children is cpuset specific, there's no reason to have this rather odd option activation mechanism in cgroup core. cpuset can check the flag from its ->css_allocate() and take the necessary action. Move cpuset_post_clone() logic to the end of cpuset_css_alloc() and remove cgroup_subsys->post_clone(). Loosely based on Glauber's "generalize post_clone into post_create" patch. Signed-off-by: Tejun Heo <tj@kernel.org> Original-patch-by: Glauber Costa <glommer@parallels.com> Original-patch: <1351686554-22592-2-git-send-email-glommer@parallels.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>
2012-11-19cgroup: s/CGRP_CLONE_CHILDREN/CGRP_CPUSET_CLONE_CHILDREN/Tejun Heo
clone_children is only meaningful for cpuset and will stay that way. Rename the flag to reflect that and update documentation. Also, drop clone_children() wrapper in cgroup.c. The thin wrapper is used only a few times and one of them will go away soon. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>
2012-11-19cgroup: rename ->create/post_create/pre_destroy/destroy() to ↵Tejun Heo
->css_alloc/online/offline/free() Rename cgroup_subsys css lifetime related callbacks to better describe what their roles are. Also, update documentation. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19cgroup: allow ->post_create() to failTejun Heo
There could be cases where controllers want to do initialization operations which may fail from ->post_create(). This patch makes ->post_create() return -errno to indicate failure and online_css() relay such failures. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>
2012-11-19cgroup: introduce CSS_ONLINE flag and on/offline_css() helpersTejun Heo
New helpers on/offline_css() respectively wrap ->post_create() and ->pre_destroy() invocations. online_css() sets CSS_ONLINE after ->post_create() is complete and offline_css() invokes ->pre_destroy() iff CSS_ONLINE is set and clears it while also handling the temporary dropping of cgroup_mutex. This patch doesn't introduce any behavior change at the moment but will be used to improve cgroup_create() failure path and allow ->post_create() to fail. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19cgroup: make CSS_* flags bit masks instead of bit positionsTejun Heo
Currently, CSS_* flags are defined as bit positions and manipulated using atomic bitops. There's no reason to use atomic bitops for them and bit positions are clunkier to deal with than bit masks. Make CSS_* bit masks instead and use the usual C bitwise operators to access them. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-19cgroup: cgroup->dentry isn't a RCU pointerTejun Heo
cgroup->dentry is marked and used as a RCU pointer; however, it isn't one - the final dentry put doesn't go through call_rcu(). cgroup and dentry share the same RCU freeing rule via synchronize_rcu() in cgroup_diput() (kfree_rcu() used on cgrp is unnecessary). If cgrp is accessible under RCU read lock, so is its dentry and dereferencing cgrp->dentry doesn't need any further RCU protection or annotation. While not being accurate, before the previous patch, the RCU accessors served a purpose as memory barriers - cgroup->dentry used to be assigned after the cgroup was made visible to cgroup_path(), so the assignment and dereferencing in cgroup_path() needed the memory barrier pair. Now that list_add_tail_rcu() happens after cgroup->dentry is assigned, this no longer is necessary. Remove the now unnecessary and misleading RCU annotations from cgroup->dentry. To make up for the removal of rcu_dereference_check() in cgroup_path(), add an explicit rcu_lockdep_assert(), which asserts the dereference rule of @cgrp, not cgrp->dentry. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-09cgroup: implement generic child / descendant walk macrosTejun Heo
Currently, cgroup doesn't provide any generic helper for walking a given cgroup's children or descendants. This patch adds the following three macros. * cgroup_for_each_child() - walk immediate children of a cgroup. * cgroup_for_each_descendant_pre() - visit all descendants of a cgroup in pre-order tree traversal. * cgroup_for_each_descendant_post() - visit all descendants of a cgroup in post-order tree traversal. All three only require the user to hold RCU read lock during traversal. Verifying that each iterated cgroup is online is the responsibility of the user. When used with proper synchronization, cgroup_for_each_descendant_pre() can be used to propagate state updates to descendants in reliable way. See comments for details. v2: s/config/state/ in commit message and comments per Michal. More documentation on synchronization rules. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-09cgroup: use rculist ops for cgroup->childrenTejun Heo
Use RCU safe list operations for cgroup->children. This will be used to implement cgroup children / descendant walking which can be used by controllers. Note that cgroup_create() now puts a new cgroup at the end of the ->children list instead of head. This isn't strictly necessary but is done so that the iteration order is more conventional. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com>
2012-11-09cgroup: add cgroup_subsys->post_create()Tejun Heo
Currently, there's no way for a controller to find out whether a new cgroup finished all ->create() allocatinos successfully and is considered "live" by cgroup. This becomes a problem later when we add generic descendants walking to cgroup which can be used by controllers as controllers don't have a synchronization point where it can synchronize against new cgroups appearing in such walks. This patch adds ->post_create(). It's called after all ->create() succeeded and the cgroup is linked into the generic cgroup hierarchy. This plays the counterpart of ->pre_destroy(). When used in combination with the to-be-added generic descendant iterators, ->post_create() can be used to implement reliable state inheritance. It will be explained with the descendant iterators. v2: Added a paragraph about its future use w/ descendant iterators per Michal. v3: Forgot to add ->post_create() invocation to cgroup_load_subsys(). Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Glauber Costa <glommer@parallels.com>
2012-11-05Merge branch 'cgroup-rmdir-updates' into cgroup/for-3.8Tejun Heo
Pull rmdir updates into for-3.8 so that further callback updates can be put on top. This pull created a trivial conflict between the following two commits. 8c7f6edbda ("cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them") ed95779340 ("cgroup: kill cgroup_subsys->__DEPRECATED_clear_css_refs") The former added a field to cgroup_subsys and the latter removed one from it. They happen to be colocated causing the conflict. Keeping what's added and removing what's removed resolves the conflict. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-11-05cgroup: make ->pre_destroy() return voidTejun Heo
All ->pre_destory() implementations return 0 now, which is the only allowed return value. Make it return void. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Vivek Goyal <vgoyal@redhat.com>
2012-11-05cgroup: remove CGRP_WAIT_ON_RMDIR, cgroup_exclude_rmdir() and ↵Tejun Heo
cgroup_release_and_wakeup_rmdir() CGRP_WAIT_ON_RMDIR is another kludge which was added to make cgroup destruction rollback somewhat working. cgroup_rmdir() used to drain CSS references and CGRP_WAIT_ON_RMDIR and the associated waitqueue and helpers were used to allow the task performing rmdir to wait for the next relevant event. Unfortunately, the wait is visible to controllers too and the mechanism got exposed to memcg by 887032670d ("cgroup avoid permanent sleep at rmdir"). Now that the draining and retries are gone, CGRP_WAIT_ON_RMDIR is unnecessary. Remove it and all the mechanisms supporting it. Note that memcontrol.c changes are essentially revert of 887032670d ("cgroup avoid permanent sleep at rmdir"). Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Balbir Singh <bsingharora@gmail.com>
2012-11-05cgroup: kill CSS_REMOVEDTejun Heo
CSS_REMOVED is one of the several contortions which were necessary to support css reference draining on cgroup removal. All css->refcnts which need draining should be deactivated and verified to equal zero atomically w.r.t. css_tryget(). If any one isn't zero, all refcnts needed to be re-activated and css_tryget() shouldn't fail in the process. This was achieved by letting css_tryget() busy-loop until either the refcnt is reactivated (failed removal attempt) or CSS_REMOVED is set (committing to removal). Now that css refcnt draining is no longer used, there's no need for atomic rollback mechanism. css_tryget() simply can look at the reference count and fail if it's deactivated - it's never getting re-activated. This patch removes CSS_REMOVED and updates __css_tryget() to fail if the refcnt is deactivated. As deactivation and removal are a single step now, they no longer need to be protected against css_tryget() happening from irq context. Remove local_irq_disable/enable() from cgroup_rmdir(). Note that this removes css_is_removed() whose only user is VM_BUG_ON() in memcontrol.c. We can replace it with a check on the refcnt but given that the only use case is a debug assert, I think it's better to simply unexport it. v2: Comment updated and explanation on local_irq_disable/enable() added per Michal Hocko. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2012-11-05cgroup: kill cgroup_subsys->__DEPRECATED_clear_css_refsTejun Heo
2ef37d3fe4 ("memcg: Simplify mem_cgroup_force_empty_list error handling") removed the last user of __DEPRECATED_clear_css_refs. This patch removes __DEPRECATED_clear_css_refs and mechanisms to support it. * Conditionals dependent on __DEPRECATED_clear_css_refs removed. * cgroup_clear_css_refs() can no longer fail. All that needs to be done are deactivating refcnts, setting CSS_REMOVED and putting the base reference on each css. Remove cgroup_clear_css_refs() and the failure path, and open-code the loops into cgroup_rmdir(). This patch keeps the two for_each_subsys() loops separate while open coding them. They can be merged now but there are scheduled changes which need them to be separate, so keep them separate to reduce the amount of churn. local_irq_save/restore() from cgroup_clear_css_refs() are replaced with local_irq_disable/enable() for simplicity. This is safe as cgroup_rmdir() is always called with IRQ enabled. Note that this IRQ switching is necessary to ensure that css_tryget() isn't called from IRQ context on the same CPU while lower context is between CSS deactivation and setting CSS_REMOVED as css_tryget() would hang forever in such cases waiting for CSS to be re-activated or CSS_REMOVED set. This will go away soon. v2: cgroup_call_pre_destroy() removal dropped per Michal. Commit message updated to explain local_irq_disable/enable() conversion. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Michal Hocko <mhocko@suse.cz> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizefan@huawei.com>
2012-10-16cgroup: cgroup_subsys->fork() should be called after the task is added to ↵Tejun Heo
css_set cgroup core has a bug which violates a basic rule about event notifications - when a new entity needs to be added, you add that to the notification list first and then make the new entity conform to the current state. If done in the reverse order, an event happening inbetween will be lost. cgroup_subsys->fork() is invoked way before the new task is added to the css_set. Currently, cgroup_freezer is the only user of ->fork() and uses it to make new tasks conform to the current state of the freezer. If FROZEN state is requested while fork is in progress between cgroup_fork_callbacks() and cgroup_post_fork(), the child could escape freezing - the cgroup isn't frozen when ->fork() is called and the freezer couldn't see the new task on the css_set. This patch moves cgroup_subsys->fork() invocation to cgroup_post_fork() after the new task is added to the css_set. cgroup_fork_callbacks() is removed. Because now a task may be migrated during cgroup_subsys->fork(), freezer_fork() is updated so that it adheres to the usual RCU locking and the rather pointless comment on why locking can be different there is removed (if it doesn't make anything simpler, why even bother?). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@vger.kernel.org
2012-10-02Merge branch 'for-3.7-hierarchy' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup hierarchy update from Tejun Heo: "Currently, different cgroup subsystems handle nested cgroups completely differently. There's no consistency among subsystems and the behaviors often are outright broken. People at least seem to agree that the broken hierarhcy behaviors need to be weeded out if any progress is gonna be made on this front and that the fallouts from deprecating the broken behaviors should be acceptable especially given that the current behaviors don't make much sense when nested. This patch makes cgroup emit warning messages if cgroups for subsystems with broken hierarchy behavior are nested to prepare for fixing them in the future. This was put in a separate branch because more related changes were expected (didn't make it this round) and the memory cgroup wanted to pull in this and make changes on top." * 'for-3.7-hierarchy' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them
2012-09-14cgroup: mark subsystems with broken hierarchy support and whine if cgroups ↵Tejun Heo
are nested for them Currently, cgroup hierarchy support is a mess. cpu related subsystems behave correctly - configuration, accounting and control on a parent properly cover its children. blkio and freezer completely ignore hierarchy and treat all cgroups as if they're directly under the root cgroup. Others show yet different behaviors. These differing interpretations of cgroup hierarchy make using cgroup confusing and it impossible to co-mount controllers into the same hierarchy and obtain sane behavior. Eventually, we want full hierarchy support from all subsystems and probably a unified hierarchy. Users using separate hierarchies expecting completely different behaviors depending on the mounted subsystem is deterimental to making any progress on this front. This patch adds cgroup_subsys.broken_hierarchy and sets it to %true for controllers which are lacking in hierarchy support. The goal of this patch is two-fold. * Move users away from using hierarchy on currently non-hierarchical subsystems, so that implementing proper hierarchy support on those doesn't surprise them. * Keep track of which controllers are broken how and nudge the subsystems to implement proper hierarchy support. For now, start with a single warning message. We can whine louder later on. v2: Fixed a typo spotted by Michal. Warning message updated. v3: Updated memcg part so that it doesn't generate warning in the cases where .use_hierarchy=false doesn't make the behavior different from root.use_hierarchy=true. Fixed a typo spotted by Glauber. v4: Check ->broken_hierarchy after cgroup creation is complete so that ->create() can affect the result per Michal. Dropped unnecessary memcg root handling per Michal. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Turner <pjt@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Thomas Graf <tgraf@suug.ch> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2012-09-14cgroup: Define CGROUP_SUBSYS_COUNT according the configurationDaniel Wagner
Since we know exactly how many subsystems exists at compile time we are able to define CGROUP_SUBSYS_COUNT correctly. CGROUP_SUBSYS_COUNT will be at max 12 (all controllers enabled). Depending on the architecture we safe either 32 - 12 pointers (80 bytes) or 64 - 12 pointers (416 bytes) per cgroup. With this change we can also remove the temporary placeholder to avoid compilation errors. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: netdev@vger.kernel.org Cc: cgroups@vger.kernel.org
2012-09-14cgroup: Assign subsystem IDs during compile timeDaniel Wagner
WARNING: With this change it is impossible to load external built controllers anymore. In case where CONFIG_NETPRIO_CGROUP=m and CONFIG_NET_CLS_CGROUP=m is set, corresponding subsys_id should also be a constant. Up to now, net_prio_subsys_id and net_cls_subsys_id would be of the type int and the value would be assigned during runtime. By switching the macro definition IS_SUBSYS_ENABLED from IS_BUILTIN to IS_ENABLED, all *_subsys_id will have constant value. That means we need to remove all the code which assumes a value can be assigned to net_prio_subsys_id and net_cls_subsys_id. A close look is necessary on the RCU part which was introduces by following patch: commit f845172531fb7410c7fb7780b1a6e51ee6df7d52 Author: Herbert Xu <herbert@gondor.apana.org.au> Mon May 24 09:12:34 2010 Committer: David S. Miller <davem@davemloft.net> Mon May 24 09:12:34 2010 cls_cgroup: Store classid in struct sock Tis code was added to init_cgroup_cls() /* We can't use rcu_assign_pointer because this is an int. */ smp_wmb(); net_cls_subsys_id = net_cls_subsys.subsys_id; respectively to exit_cgroup_cls() net_cls_subsys_id = -1; synchronize_rcu(); and in module version of task_cls_classid() rcu_read_lock(); id = rcu_dereference(net_cls_subsys_id); if (id >= 0) classid = container_of(task_subsys_state(p, id), struct cgroup_cls_state, css)->classid; rcu_read_unlock(); Without an explicit explaination why the RCU part is needed. (The rcu_deference was fixed by exchanging it to rcu_derefence_index_check() in a later commit, but that is a minor detail.) So here is my pondering why it was introduced and why it safe to remove it now. Note that this code was copied over to net_prio the reasoning holds for that subsystem too. The idea behind the RCU use for net_cls_subsys_id is to make sure we get a valid pointer back from task_subsys_state(). task_subsys_state() is just blindly accessing the subsys array and returning the pointer. Obviously, passing in -1 as id into task_subsys_state() returns an invalid value (out of lower bound). So this code makes sure that only after module is loaded and the subsystem registered, the id is assigned. Before unregistering the module all old readers must have left the critical section. This is done by assigning -1 to the id and issuing a synchronized_rcu(). Any new readers wont call task_subsys_state() anymore and therefore it is safe to unregister the subsystem. The new code relies on the same trick, but it looks at the subsys pointer return by task_subsys_state() (remember the id is constant and therefore we allways have a valid index into the subsys array). No precautions need to be taken during module loading module. Eventually, all CPUs will get a valid pointer back from task_subsys_state() because rebind_subsystem() which is called after the module init() function will assigned subsys[net_cls_subsys_id] the newly loaded module subsystem pointer. When the subsystem is about to be removed, rebind_subsystem() will called before the module exit() function. In this case, rebind_subsys() will assign subsys[net_cls_subsys_id] a NULL pointer and then it calls synchronize_rcu(). All old readers have left by then the critical section. Any new reader wont access the subsystem anymore. At this point we are safe to unregister the subsystem. No synchronize_rcu() call is needed. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: netdev@vger.kernel.org Cc: cgroups@vger.kernel.org
2012-09-14cgroup: Wrap subsystem selection macroDaniel Wagner
Before we are able to define all subsystem ids at compile time we need a more fine grained control what gets defined when we include cgroup_subsys.h. For example we define the enums for the subsystems or to declare for struct cgroup_subsys (builtin subsystem) by including cgroup_subsys.h and defining SUBSYS accordingly. Currently, the decision if a subsys is used is defined inside the header by testing if CONFIG_*=y is true. By moving this test outside of cgroup_subsys.h we are able to control it on the include level. This is done by introducing IS_SUBSYS_ENABLED which then is defined according the task, e.g. is CONFIG_*=y or CONFIG_*=m. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: netdev@vger.kernel.org Cc: cgroups@vger.kernel.org
2012-09-14cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNTDaniel Wagner
CGROUP_BUILTIN_SUBSYS_COUNT is used as start index or stop index when looping over the subsys array looking either at the builtin or the module subsystems. Since all the builtin subsystems have an id which is lower then CGROUP_BUILTIN_SUBSYS_COUNT we know that any module will have an id larger than CGROUP_BUILTIN_SUBSYS_COUNT. In short the ids are sorted. We are about to change id assignment to happen only at compile time later in this series. That means we can't rely on the above trick since all ids will always be defined at compile time. Furthermore, ordering the builtin subsystems and the module subsystems is not really necessary. So we need a different way to know which subsystem is a builtin or a module one. We can use the subsys[]->module pointer for this. Any place where we need to know if a subsys is module we just check for the pointer. If it is NULL then the subsystem is a builtin one. With this we are able to drop the CGROUP_BUILTIN_SUBSYS_COUNT enum. Though we need to introduce a temporary placeholder so that we don't get a compilation error when only CONFIG_CGROUP is selected and no single controller. An empty enum definition is not valid. Later in this series we are able to remove the placeholder again. And with this change we get a fix for this: kernel/cgroup.c: In function ‘cgroup_load_subsys’: kernel/cgroup.c:4326:38: warning: array subscript is below array bounds [-Warray-bounds] when CONFIG_CGROUP=y and no built in controller was enabled. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: netdev@vger.kernel.org Cc: cgroups@vger.kernel.org
2012-08-24cgroup: add xattr supportAristeu Rozanski
This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-06-07cgroup: remove hierarchy_mutexLi Zefan
It was introduced for memcg to iterate cgroup hierarchy without holding cgroup_mutex, but soon after that it was replaced with a lockless way in memcg. No one used hierarchy_mutex since that, so remove it. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-11cgroup: remove cgroup_subsys->populate()Tejun Heo
With memcg converted, cgroup_subsys->populate() doesn't have any user left. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2012-04-01cgroup: make css->refcnt clearing on cgroup removal optionalTejun Heo
Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01cgroup: use negative bias on css->refcnt to block css_tryget()Tejun Heo
When a cgroup is about to be removed, cgroup_clear_css_refs() is called to check and ensure that there are no active css references. This is currently achieved by dropping the refcnt to zero iff it has only the base ref. If all css refs could be dropped to zero, ref clearing is successful and CSS_REMOVED is set on all css. If not, the base ref is restored. While css ref is zero w/o CSS_REMOVED set, any css_tryget() attempt on it busy loops so that they are atomic w.r.t. the whole css ref clearing. This does work but dropping and re-instating the base ref is somewhat hairy and makes it difficult to add more logic to the put path as there are two of them - the regular css_put() and the reversible base ref clearing. This patch updates css ref clearing such that blocking new css_tryget() and putting the base ref are separate operations. CSS_DEACT_BIAS, defined as INT_MIN, is added to css->refcnt and css_tryget() busy loops while refcnt is negative. After all css refs are deactivated, if they were all one, ref clearing succeeded and CSS_REMOVED is set and the base ref is put using the regular css_put(); otherwise, CSS_DEACT_BIAS is subtracted from the refcnts and the original postive values are restored. css_refcnt() accessor which always returns the unbiased positive reference counts is added and used to simplify refcnt usages. While at it, relocate and reformat comments in cgroup_has_css_refs(). This separates css->refcnt deactivation and putting the base ref, which enables the next patch to make ref clearing optional. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01cgroup: implement cgroup_rm_cftypes()Tejun Heo
Implement cgroup_rm_cftypes() which removes an array of cftypes from a subsystem. It can be called whether the target subsys is attached or not. cgroup core will remove the specified file from all existing cgroups. This will be used to improve sub-subsys modularity and will be helpful for unified hierarchy. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01cgroup: introduce struct cfentTejun Heo
This patch adds cfent (cgroup file entry) which is the association between a cgroup and a file. This is in-cgroup representation of files under a cgroup directory. This simplifies walking walking cgroup files and thus cgroup_clear_directory(), which is now implemented in two parts - cgroup_rm_file() and a loop around it. cgroup_rm_file() will be used to implement cftype removal and cfent is scheduled to serve cgroup specific per-file data (e.g. for sysfs-like "sever" semantics). v2: - cfe was freed from cgroup_rm_file() which led to use-after-free if the file had openers at the time of removal. Moved to cgroup_diput(). - cgroup_clear_directory() triggered WARN_ON_ONCE() if d_subdirs wasn't empty after removing all files. This triggered spuriously if some files were open during directory clearing. Removed. v3: - In cgroup_diput(), WARN_ONCE(!list_empty(&cfe->node)) could be spuriously triggered for root cgroups because they don't go through cgroup_clear_directory() on unmount. Don't trigger WARN for root cgroups. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Glauber Costa <glommer@parallels.com>
2012-04-01cgroup: remove cgroup_add_file[s]()Tejun Heo
No controller is using cgroup_add_files[s](). Unexport them, and convert cgroup_add_files() to handle NULL entry terminated array instead of taking count explicitly and continue creation on failure for internal use. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01cgroup: implement cgroup_add_cftypes() and friendsTejun Heo
Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01cgroup: build list of all cgroups under a given cgroupfs_rootTejun Heo
Build a list of all cgroups anchored at cgroupfs_root->allcg_list and going through cgroup->allcg_node. The list is protected by cgroup_mutex and will be used to improve cgroup file handling. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-03-22cgroup: revert ss_id_lock to spinlockHugh Dickins
Commit c1e2ee2dc436 ("memcg: replace ss->id_lock with a rwlock") has now been seen to cause the unfair behavior we should have expected from converting a spinlock to an rwlock: softlockup in cgroup_mkdir(), whose get_new_cssid() is waiting for the wlock, while there are 19 tasks using the rlock in css_get_next() to get on with their memcg workload (in an artificial test, admittedly). Yet lib/idr.c was made suitable for RCU way back: revert that commit, restoring ss->id_lock to a spinlock. Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Eric Dumazet <eric.dumazet@gmail.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>
2012-02-02cgroup: remove cgroup_subsys argument from callbacksLi Zefan
The argument is not used at all, and it's not necessary, because a specific callback handler of course knows which subsys it belongs to. Now only ->pupulate() takes this argument, because the handlers of this callback always call cgroup_add_file()/cgroup_add_files(). So we reduce a few lines of code, though the shrinking of object size is minimal. 16 files changed, 113 insertions(+), 162 deletions(-) text data bss dec hex filename 5486240 656987 7039960 13183187 c928d3 vmlinux.o.orig 5486170 656987 7039960 13183117 c9288d vmlinux.o Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-01-20cgroup: move struct cgroup_pidlist out from the header fileLi Zefan
It's internally used only. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-01-20cgroup: remove cgroup_attach_task_current_cg()Li Zefan
It's just a wrapper of cgroup_attach_task_all(), and it's no longer used after commit 87d6a412bd1ed82c14cabd4b408003b23bbd2880 (vhost: fix attach to cgroups regression) Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-01-09Merge branch 'for-3.3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup * 'for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits) cgroup: fix to allow mounting a hierarchy by name cgroup: move assignement out of condition in cgroup_attach_proc() cgroup: Remove task_lock() from cgroup_post_fork() cgroup: add sparse annotation to cgroup_iter_start() and cgroup_iter_end() cgroup: mark cgroup_rmdir_waitq and cgroup_attach_proc() as static cgroup: only need to check oldcgrp==newgrp once cgroup: remove redundant get/put of task struct cgroup: remove redundant get/put of old css_set from migrate cgroup: Remove unnecessary task_lock before fetching css_set on migration cgroup: Drop task_lock(parent) on cgroup_fork() cgroups: remove redundant get/put of css_set from css_set_check_fetched() resource cgroups: remove bogus cast cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task() cgroup, cpuset: don't use ss->pre_attach() cgroup: don't use subsys->can_attach_task() or ->attach_task() cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), cancel_attach() and attach() cgroup: improve old cgroup handling in cgroup_attach_proc() cgroup: always lock threadgroup during migration threadgroup: extend threadgroup_lock() to cover exit and exec threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem ... Fix up conflict in kernel/cgroup.c due to commit e0197aae59e5: "cgroups: fix a css_set not found bug in cgroup_attach_proc" that already mentioned that the bug is fixed (differently) in Tejun's cgroup patchset. This one, in other words.
2012-01-04cgroup: propagate mode_tAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-12-13cgroup: kill subsys->can_attach_task(), pre_attach() and attach_task()Tejun Heo
These three methods are no longer used. Kill them. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Menage <paul@paulmenage.org> Cc: Li Zefan <lizf@cn.fujitsu.com>
2011-12-13cgroup: introduce cgroup_taskset and use it in subsys->can_attach(), ↵Tejun Heo
cancel_attach() and attach() Currently, there's no way to pass multiple tasks to cgroup_subsys methods necessitating the need for separate per-process and per-task methods. This patch introduces cgroup_taskset which can be used to pass multiple tasks and their associated cgroups to cgroup_subsys methods. Three methods - can_attach(), cancel_attach() and attach() - are converted to use cgroup_taskset. This unifies passed parameters so that all methods have access to all information. Conversions in this patchset are identical and don't introduce any behavior change. -v2: documentation updated as per Paul Menage's suggestion. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Menage <paul@paulmenage.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: James Morris <jmorris@namei.org>
2011-11-02memcg: replace ss->id_lock with a rwlockAndrew Bresticker
While back-porting Johannes Weiner's patch "mm: memcg-aware global reclaim" for an internal effort, we noticed a significant performance regression during page-reclaim heavy workloads due to high contention of the ss->id_lock. This lock protects idr map, and serializes calls to idr_get_next() in css_get_next() (which is used during the memcg hierarchy walk). Since idr_get_next() is just doing a look up, we need only serialize it with respect to idr_remove()/idr_get_new(). By making the ss->id_lock a rwlock, contention is greatly reduced and performance improves. Tested: cat a 256m file from a ramdisk in a 128m container 50 times on each core (one file + container per core) in parallel on a NUMA machine. Result is the time for the test to complete in 1 of the containers. Both kernels included Johannes' memcg-aware global reclaim patches. Before rwlock patch: 1710.778s After rwlock patch: 152.227s Signed-off-by: Andrew Bresticker <abrestic@google.com> Cc: Paul Menage <menage@gmail.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-08rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_checkMichal Hocko
Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check use rcu_read_lock_held as a part of condition automatically so callers do not have to do that as well. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-05-27cgroup: remove the ns_cgroupDaniel Lezcano
The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier and leads to some problems: * cgroup creation is out-of-control * cgroup name can conflict when pids are looping * it is not possible to have a single process handling a lot of namespaces without falling in a exponential creation time * we may want to create a namespace without creating a cgroup The ns_cgroup was replaced by a compatibility flag 'clone_children', where a newly created cgroup will copy the parent cgroup values. The userspace has to manually create a cgroup and add a task to the 'tasks' file. This patch removes the ns_cgroup as suggested in the following thread: https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html The 'cgroup_clone' function is removed because it is no longer used. This is a userspace-visible change. Commit 45531757b45c ("cgroup: notify ns_cgroup deprecated") (merged into 2.6.27) caused the kernel to emit a printk warning users that the feature is planned for removal. Since that time we have heard from XXX users who were affected by this. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Acked-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-27cgroups: add per-thread subsystem callbacksBen Blum
Add cgroup subsystem callbacks for per-thread attachment in atomic contexts Add can_attach_task(), pre_attach(), and attach_task() as new callbacks for cgroups's subsystem interface. Unlike can_attach and attach, these are for per-thread operations, to be called potentially many times when attaching an entire threadgroup. Also, the old "bool threadgroup" interface is removed, as replaced by this. All subsystems are modified for the new interface - of note is cpuset, which requires from/to nodemasks for attach to be globally scoped (though per-cpuset would work too) to persist from its pre_attach to attach_task and attach. This is a pre-patch for cgroup-procs-writable.patch. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>