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2015-01-06cgroup: add dummy css_put() for !CONFIG_CGROUPSTejun Heo1-0/+4
This will later be depended upon by the scheduled cgroup writeback support. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-12-12Merge branch 'for-3.19' of ↵Linus Torvalds1-0/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup update from Tejun Heo: "cpuset got simplified a bit. cgroup core got a fix on unified hierarchy and grew some effective css related interfaces which will be used for blkio support for writeback IO traffic which is currently being worked on" * 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: implement cgroup_get_e_css() cgroup: add cgroup_subsys->css_e_css_changed() cgroup: add cgroup_subsys->css_released() cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write() cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask() cpuset: lock vs unlock typo cpuset: simplify cpuset_node_allowed API cpuset: convert callback_mutex to a spinlock
2014-12-11Merge branch 'akpm' (patchbomb from Andrew)Linus Torvalds1-0/+26
Merge first patchbomb from Andrew Morton: - a few minor cifs fixes - dma-debug upadtes - ocfs2 - slab - about half of MM - procfs - kernel/exit.c - panic.c tweaks - printk upates - lib/ updates - checkpatch updates - fs/binfmt updates - the drivers/rtc tree - nilfs - kmod fixes - more kernel/exit.c - various other misc tweaks and fixes * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits) exit: pidns: fix/update the comments in zap_pid_ns_processes() exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting exit: exit_notify: re-use "dead" list to autoreap current exit: reparent: call forget_original_parent() under tasklist_lock exit: reparent: avoid find_new_reaper() if no children exit: reparent: introduce find_alive_thread() exit: reparent: introduce find_child_reaper() exit: reparent: document the ->has_child_subreaper checks exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper() exit: reparent: fix the cross-namespace PR_SET_CHILD_SUBREAPER reparenting exit: reparent: fix the dead-parent PR_SET_CHILD_SUBREAPER reparenting exit: proc: don't try to flush /proc/tgid/task/tgid exit: release_task: fix the comment about group leader accounting exit: wait: drop tasklist_lock before psig->c* accounting exit: wait: don't use zombie->real_parent exit: wait: cleanup the ptrace_reparented() checks usermodehelper: kill the kmod_thread_locker logic usermodehelper: don't use CLONE_VFORK for ____call_usermodehelper() fs/hfs/catalog.c: fix comparison bug in hfs_cat_keycmp nilfs2: fix the nilfs_iget() vs. nilfs_new_inode() races ...
2014-12-11mm: memcontrol: take a css reference for each charged pageJohannes Weiner1-0/+26
Charges currently pin the css indirectly by playing tricks during css_offline(): user pages stall the offlining process until all of them have been reparented, whereas kmemcg acquires a keep-alive reference if outstanding kernel pages are detected at that point. In preparation for removing all this complexity, make the pinning explicit and acquire a css references for every charged page. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.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>
2014-11-19kill f_dentry usesAl Viro1-2/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-18cgroup: implement cgroup_get_e_css()Tejun Heo1-0/+2
Implement cgroup_get_e_css() which finds and gets the effective css for the specified cgroup and subsystem combination. This function always returns a valid pinned css. This will be used by cgroup writeback support. While at it, add comment to cgroup_e_css() to explain why that function is different from cgroup_get_e_css() and has to test cgrp->child_subsys_mask instead of cgroup_css(cgrp, ss). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2014-11-18cgroup: add cgroup_subsys->css_e_css_changed()Tejun Heo1-0/+1
Add a new cgroup_subsys operatoin ->css_e_css_changed(). This is invoked if any of the effective csses seen from the css's cgroup may have changed. This will be used to implement cgroup writeback support. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2014-11-18cgroup: add cgroup_subsys->css_released()Tejun Heo1-0/+1
Add a new cgroup subsys callback css_released(). This is called when the reference count of the css (cgroup_subsys_state) reaches zero before RCU scheduling free. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2014-09-19cgroup: remove CGRP_RELEASABLE flagZefan Li1-5/+0
We call put_css_set() after setting CGRP_RELEASABLE flag in cgroup_task_migrate(), but in other places we call it without setting the flag. I don't see the necessity of this flag. Moreover once the flag is set, it will never be cleared, unless writing to the notify_on_release control file, so it can be quite confusing if we look at the output of debug.releasable. # mount -t cgroup -o debug xxx /cgroup # mkdir /cgroup/child # cat /cgroup/child/debug.releasable 0 <-- shows 0 though the cgroup is empty # echo $$ > /cgroup/child/tasks # cat /cgroup/child/debug.releasable 0 # echo $$ > /cgroup/tasks && echo $$ > /cgroup/child/tasks # cat /proc/child/debug.releasable 1 <-- shows 1 though the cgroup is not empty This patch removes the flag, and now debug.releasable shows if the cgroup is empty or not. Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-19cgroup: remove redundant check in cgroup_ino()Zefan Li1-5/+2
After we implemented default unified hierarchy, cgrp->kn can never be NULL. Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18cgroup: simplify proc_cgroup_show()Zefan Li1-1/+2
Use the ONE macro instead of REG, and we can simplify proc_cgroup_show(). Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18cgroup: use a per-cgroup work for release agentZefan Li1-7/+3
Instead of using a global work to schedule release agent on removable cgroups, we change to use a per-cgroup work to do this, which makes the code much simpler. v2: use a dedicated work instead of reusing css->destroy_work. (Tejun) Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18cgroup: remove some useless forward declarationsLi Zefan1-1/+0
Signed-off-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-07-15cgroup: make CFTYPE_ONLY_ON_DFL and CFTYPE_NO_ internal to cgroup coreTejun Heo1-2/+4
cgroup now distinguishes cftypes for the default and legacy hierarchies more explicitly by using separate arrays and CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE should be and are used only inside cgroup core proper. Let's make it clear that the flags are internal by prefixing them with double underscores. CFTYPE_INSANE is renamed to __CFTYPE_NOT_ON_DFL for consistency. The two flags are also collected and assigned bits >= 16 so that they aren't mixed with the published flags. v2: Convert the extra ones in cgroup_exit_cftypes() which are added by revision to the previous patch. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-07-15cgroup: distinguish the default and legacy hierarchies when handling cftypesTejun Heo1-2/+7
Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15cgroup: replace cgroup_add_cftypes() with cgroup_add_legacy_cftypes()Tejun Heo1-1/+1
Currently, cftypes added by cgroup_add_cftypes() are used for both the unified default hierarchy and legacy ones and subsystems can mark each file with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE if it has to appear only on one of them. This is quite hairy and error-prone. Also, we may end up exposing interface files to the default hierarchy without thinking it through. cgroup_subsys will grow two separate cftype addition functions and apply each only on the hierarchies of the matching type. This will allow organizing cftypes in a lot clearer way and encourage subsystems to scrutinize the interface which is being exposed in the new default hierarchy. In preparation, this patch adds cgroup_add_legacy_cftypes() which currently is a simple wrapper around cgroup_add_cftypes() and replaces all cgroup_add_cftypes() usages with it. While at it, this patch drops a completely spurious return from __hugetlb_cgroup_file_init(). This patch doesn't introduce any functional differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypesTejun Heo1-1/+1
Currently, cgroup_subsys->base_cftypes is used for both the unified default hierarchy and legacy ones and subsystems can mark each file with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE if it has to appear only on one of them. This is quite hairy and error-prone. Also, we may end up exposing interface files to the default hierarchy without thinking it through. cgroup_subsys will grow two separate cftype arrays and apply each only on the hierarchies of the matching type. This will allow organizing cftypes in a lot clearer way and encourage subsystems to scrutinize the interface which is being exposed in the new default hierarchy. In preparation, this patch renames cgroup_subsys->base_cftypes to cgroup_subsys->legacy_cftypes. This patch is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-09cgroup: remove sane_behavior support on non-default hierarchiesTejun Heo1-71/+54
sane_behavior has been used as a development vehicle for the default unified hierarchy. Now that the default hierarchy is in place, the flag became redundant and confusing as its usage is allowed on all hierarchies. There are gonna be either the default hierarchy or legacy ones. Let's make that clear by removing sane_behavior support on non-default hierarchies. This patch replaces cgroup_sane_behavior() with cgroup_on_dfl(). The comment on top of CGRP_ROOT_SANE_BEHAVIOR is moved to on top of cgroup_on_dfl() with sane_behavior specific part dropped. On the default and legacy hierarchies w/o sane_behavior, this shouldn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz>
2014-07-09cgroup: remove CGRP_ROOT_OPTION_MASKTejun Heo1-3/+0
cgroup_root->flags only contains CGRP_ROOT_* flags and there's no reason to mask the flags. Remove CGRP_ROOT_OPTION_MASK. This doesn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-07-09cgroup: implement cgroup_subsys->depends_onTejun Heo1-0/+9
Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09cgroup: implement cgroup_subsys->css_reset()Tejun Heo1-0/+1
cgroup is implementing support for subsystem dependency which would require a way to enable a subsystem even when it's not directly configured through "cgroup.subtree_control". The previous patches added support for explicitly and implicitly enabled subsystems and showing/hiding their interface files. An explicitly enabled subsystem may become implicitly enabled if it's turned off through "cgroup.subtree_control" but there are subsystems depending on it. In such cases, the subsystem, as it's turned off when seen from userland, shouldn't enforce any resource control. Also, the subsystem may be explicitly turned on later again and its interface files should be as close to the intial state as possible. This patch adds cgroup_subsys->css_reset() which is invoked when a css is hidden. The callback should disable resource control and reset the state to the vanilla state. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09cgroup: make interface files visible iff enabled on cgroup->subtree_controlTejun Heo1-0/+2
cgroup is implementing support for subsystem dependency which would require a way to enable a subsystem even when it's not directly configured through "cgroup.subtree_control". The preceding patch distinguished cgroup->subtree_control and ->child_subsys_mask where the former is the subsystems explicitly configured by the userland and the latter is all enabled subsystems currently is equal to the former but will include subsystems implicitly enabled through dependency. Subsystems which are enabled due to dependency shouldn't be visible to userland. This patch updates cgroup_subtree_control_write() and create_css() such that interface files are not created for implicitly enabled subsytems. * @visible paramter is added to create_css(). Interface files are created only when true. * If an already implicitly enabled subsystem is turned on through "cgroup.subtree_control", the existing css should be used. css draining is skipped. * cgroup_subtree_control_write() computes the new target cgroup->child_subsys_mask and create/kill or show/hide csses accordingly. As the two subsystem masks are still kept identical, this patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09cgroup: introduce cgroup->subtree_controlTejun Heo1-1/+7
cgroup is implementing support for subsystem dependency which would require a way to enable a subsystem even when it's not directly configured through "cgroup.subtree_control". Previously, cgroup->child_subsys_mask directly reflected "cgroup.subtree_control" and the enabled subsystems in the child cgroups. This patch adds cgroup->subtree_control which "cgroup.subtree_control" operates on. cgroup->child_subsys_mask is now calculated from cgroup->subtree_control by cgroup_refresh_child_subsys_mask(), which sets it identical to cgroup->subtree_control for now. This will allow using cgroup->child_subsys_mask for all the enabled subsystems including the implicit ones and ->subtree_control for tracking the explicitly requested ones. This patch keeps the two masks identical and doesn't introduce any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-05-20cgroup: disallow debug controller on the default hierarchyTejun Heo1-0/+2
The debug controller, as its name suggests, exposes cgroup core internals to userland to aid debugging. Unfortunately, except for the name, there's no provision to prevent its usage in production configurations and the controller is widely enabled and mounted leaking internal details to userland. Like most other debug information, the information exposed by debug isn't interesting even for debugging itself once the related parts are working reliably. This controller has no reason for existing. This patch implements cgrp_dfl_root_inhibit_ss_mask which can suppress specific subsystems on the default hierarchy and adds the debug subsystem to it so that it can be gradually deprecated as usages move towards the unified hierarchy. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-05-16cgroup: implement css_tryget()Tejun Heo1-0/+18
Implement css_tryget() which tries to grab a cgroup_subsys_state's reference as long as it already hasn't reached zero. Combined with the recent css iterator changes to include offline && !released csses during traversal, this can be used to access csses regardless of its online state. v2: Take the new flag CSS_NO_REF into account. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16cgroup: convert cgroup_has_live_children() into css_has_online_children()Tejun Heo1-0/+2
Now that cgroup liveliness and css onliness are the same state, convert cgroup_has_live_children() into css_has_online_children() so that it can be used for actual csses too. The function now uses css_for_each_child() for iteration and is published. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: use CSS_ONLINE instead of CGRP_DEADTejun Heo1-2/+0
Use CSS_ONLINE on the self css to indicate whether a cgroup has been killed instead of CGRP_DEAD. This will allow re-using css online test for cgroup liveliness test. This doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: iterate cgroup_subsys_states directlyTejun Heo1-18/+26
Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16cgroup: introduce CSS_RELEASED and reduce css iteration fallback windowTejun Heo1-0/+1
css iterations allow the caller to drop RCU read lock. As long as the caller keeps the current position accessible, it can simply re-grab RCU read lock later and continue iteration. This is achieved by using CGRP_DEAD to detect whether the current positions next pointer is safe to dereference and if not re-iterate from the beginning to the next position using ->serial_nr. CGRP_DEAD is used as the marker to invalidate the next pointer and the only requirement is that the marker is set before the next sibling starts its RCU grace period. Because CGRP_DEAD is set at the end of cgroup_destroy_locked() but the cgroup is unlinked when the reference count reaches zero, we currently have a rather large window where this fallback re-iteration logic can be triggered. This patch introduces CSS_RELEASED which is set when a css is unlinked from its sibling list. This still keeps the re-iteration logic working while drastically reducing the window of its activation. While at it, rewrite the comment in css_next_child() to reflect the new flag and better explain the synchronization. This will also enable iterating csses directly instead of through cgroups. v2: CSS_RELEASED now assigned to 1 << 2 as 1 << 0 is used by CSS_NO_REF. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: move cgroup->serial_nr into cgroup_subsys_stateTejun Heo1-8/+8
We're moving towards using cgroup_subsys_states as the fundamental structural blocks. All csses including the cgroup->self and actual ones now form trees through css->children and ->sibling which follow the same rules as what cgroup->children and ->sibling followed. This patch moves cgroup->serial_nr which is used to implement css iteration into css. Note that all csses, regardless of their types, allocate their serial numbers from the same monotonically increasing counter. This doesn't affect the ordering needed by css iteration or cause any other material behavior changes. This will be used to update css iteration. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: move cgroup->sibling and ->children into cgroup_subsys_stateTejun Heo1-7/+4
We're moving towards using cgroup_subsys_states as the fundamental structural blocks. Let's move cgroup->sibling and ->children into cgroup_subsys_state. This is pure move without functional change and only cgroup->self's fields are actually used. Other csses will make use of the fields later. While at it, update init_and_link_css() so that it zeroes the whole css before initializing it and remove explicit zeroing of ->flags. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: remove cgroup->parentTejun Heo1-1/+0
cgroup->parent is redundant as cgroup->self.parent can also be used to determine the parent cgroup and we're moving towards using cgroup_subsys_states as the fundamental structural blocks. This patch introduces cgroup_parent() which follows cgroup->self.parent and removes cgroup->parent. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-16cgroup: remove css_parent()Tejun Heo1-18/+11
cgroup in general is moving towards using cgroup_subsys_state as the fundamental structural component and css_parent() was introduced to convert from using cgroup->parent to css->parent. It was quite some time ago and we're moving forward with making css more prominent. This patch drops the trivial wrapper css_parent() and let the users dereference css->parent. While at it, explicitly mark fields of css which are public and immutable. v2: New usage from device_cgroup.c converted. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16cgroup: skip refcnting on normal root csses and cgrp_dfl_root self cssTejun Heo1-3/+8
9395a4500404 ("cgroup: enable refcnting for root csses") enabled reference counting for root csses (cgroup_subsys_states) so that cgroup's self csses can be used to manage the lifetime of the containing cgroups. Unfortunately, this change was incorrect. During early init, cgrp_dfl_root self css refcnt is used. percpu_ref can't initialized during early init and its initialization is deferred till cgroup_init() time. This means that cpu was using percpu_ref which wasn't properly initialized. Due to the way percpu variables are laid out on x86, this didn't blow up immediately on x86 but ended up incrementing and decrementing the percpu variable at offset zero, whatever it may be; however, on other archs, this caused fault and early boot failure. As cgroup self csses for root cgroups of non-dfl hierarchies need working refcounting, we can't revert 9395a4500404. This patch adds CSS_NO_REF which explicitly inhibits reference counting on the css and sets it on all normal (non-self) csses and cgroup_dfl_root self css. v2: cgrp_dfl_root.self is the offending one. Set the flag on it. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Stephen Warren <swarren@nvidia.com> Tested-by: Stephen Warren <swarren@nvidia.com> Fixes: 9395a4500404 ("cgroup: enable refcnting for root csses")
2014-05-14cgroup: use cgroup->self.refcnt for cgroup refcntingTejun Heo1-6/+0
Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14cgroup: enable refcnting for root cssesTejun Heo1-8/+2
Currently, css_get(), css_tryget() and css_tryget_online() are noops for root csses as an optimization; however, we're planning to use css refcnts to track of cgroup lifetime too and root cgroups also need to be reference counted. Since css has been converted to percpu_refcnt, the overhead of refcnting is miniscule and this optimization isn't too meaningful anymore. Furthermore, controllers which optimize the root cgroup often never even invoke these functions in their hot paths. This patch enables refcnting for root csses too. This makes CSS_ROOT flag unused and removes it. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14cgroup: remove cgroup_destory_css_killed()Tejun Heo1-3/+0
cgroup_destroy_css_killed() is cgroup destruction stage which happens after all csses are offlined. After the recent updates, it no longer does anything other than putting the base reference. This patch removes the function and makes cgroup_destroy_locked() put the base ref at the end isntead. This also makes cgroup->nr_css unnecessary. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14cgroup: rename cgroup->dummy_css to ->self and move it to the topTejun Heo1-3/+3
cgroup->dummy_css is used as the placeholder css when performing css oriended operations on the cgroup. We're gonna shift more cgroup management to this css. Let's rename it to ->self and move it to the top. This is pure rename and field relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-13cgroup: remove cgroup->control_knTejun Heo1-1/+0
Now that cgroup_subtree_control_write() has access to the associated kernfs_open_file and thus the kernfs_node, there's no need to cache it in cgroup->control_kn on creation. Remove cgroup->control_kn and use @of->kn directly. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-13cgroup: replace cftype->trigger() with cftype->write()Tejun Heo1-8/+0
cftype->trigger() is pointless. It's trivial to ignore the input buffer from a regular ->write() operation. Convert all ->trigger() users to ->write() and remove ->trigger(). This patch doesn't introduce any visible behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz>
2014-05-13cgroup: replace cftype->write_string() with cftype->write()Tejun Heo1-9/+1
Convert all cftype->write_string() users to the new cftype->write() which maps directly to kernfs write operation and has full access to kernfs and cgroup contexts. The conversions are mostly mechanical. * @css and @cft are accessed using of_css() and of_cft() accessors respectively instead of being specified as arguments. * Should return @nbytes on success instead of 0. * @buf is not trimmed automatically. Trim if necessary. Note that blkcg and netprio don't need this as the parsers already handle whitespaces. cftype->write_string() has no user left after the conversions and removed. While at it, remove unnecessary local variable @p in cgroup_subtree_control_write() and stale comment about CGROUP_LOCAL_BUFFER_SIZE in cgroup_freezer.c. This patch doesn't introduce any visible behavior changes. v2: netprio was missing from conversion. Converted. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Aristeu Rozanski <arozansk@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: "David S. Miller" <davem@davemloft.net>
2014-05-13cgroup: implement cftype->write()Tejun Heo1-4/+23
During the recent conversion to kernfs, cftype's seq_file operations are updated so that they are directly mapped to kernfs operations and thus can fully access the associated kernfs and cgroup contexts; however, write path hasn't seen similar updates and none of the existing write operations has access to, for example, the associated kernfs_open_file. Let's introduce a new operation cftype->write() which maps directly to the kernfs write operation and has access to all the arguments and contexts. This will replace ->write_string() and ->trigger() and ease manipulation of kernfs active protection from cgroup file operations. Two accessors - of_cft() and of_css() - are introduced to enable accessing the associated cgroup context from cftype->write() which only takes kernfs_open_file for the context information. The accessors for seq_file operations - seq_cft() and seq_css() - are rewritten to wrap the of_ accessors. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-13cgroup: rename css_tryget*() to css_tryget_online*()Tejun Heo1-7/+7
Unlike the more usual refcnting, what css_tryget() provides is the distinction between online and offline csses instead of protection against upping a refcnt which already reached zero. cgroup is planning to provide actual tryget which fails if the refcnt already reached zero. Let's rename the existing trygets so that they clearly indicate that they're onliness. I thought about keeping the existing names as-are and introducing new names for the planned actual tryget; however, given that each controller participates in the synchronization of the online state, it seems worthwhile to make it explicit that these functions are about on/offline state. Rename css_tryget() to css_tryget_online() and css_tryget_from_dir() to css_tryget_online_from_dir(). This is pure rename. v2: cgroup_freezer grew new usages of css_tryget(). Update accordingly. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2014-05-13Merge branch 'for-3.15-fixes' of ↵Tejun Heo1-0/+15
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup into for-3.16 Pull to receive e37a06f10994 ("cgroup: fix the retry path of cgroup_mount()") to avoid unnecessary conflicts with planned cgroup_tree_mutex removal and also to be able to remove the temp fix added by 36c38fb7144a ("blkcg: use trylock on blkcg_pol_mutex in blkcg_reset_stats()") afterwards. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-05-13Merge branch 'for-3.16' of ↵Tejun Heo1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu into for-3.16 Pull to receive percpu_ref_tryget[_live]() changes. Planned cgroup changes will make use of them. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-05-13cgroup: introduce task_css_is_root()Tejun Heo1-0/+15
Determining the css of a task usually requires RCU read lock as that's the only thing which keeps the returned css accessible till its reference is acquired; however, testing whether a task belongs to the root can be performed without dereferencing the returned css by comparing the returned pointer against the root one in init_css_set[] which never changes. Implement task_css_is_root() which can be invoked in any context. This will be used by the scheduled cgroup_freezer change. v2: cgroup no longer supports modular controllers. No need to export init_css_set. Pointed out by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-09percpu-refcount: rename percpu_ref_tryget() to percpu_ref_tryget_live()Tejun Heo1-1/+1
percpu_ref_tryget() is different from the usual tryget semantics in that it fails if the refcnt is in its dying stage even if the refcnt hasn't reached zero yet. We're about to introduce the more conventional tryget and the current one has only one user. Let's rename it to percpu_ref_tryget_live() so that it explicitly signifies the peculiarities of its semantics. This is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Kent Overstreet <kmo@daterainc.com>
2014-05-07cgroup: remove unused CGRP_SANE_BEHAVIORTejun Heo1-2/+0
This cgroup flag has never been used. Only CGRP_ROOT_SANE_BEHAVIOR is used. Remove it. Signed-off-by: Tejun Heo <tj@kernel.org>
2014-05-04cgroup, memcg: implement css->id and convert css_from_id() to use itTejun Heo1-0/+9
Until now, cgroup->id has been used to identify all the associated csses and css_from_id() takes cgroup ID and returns the matching css by looking up the cgroup and then dereferencing the css associated with it; however, now that the lifetimes of cgroup and css are separate, this is incorrect and breaks on the unified hierarchy when a controller is disabled and enabled back again before the previous instance is released. This patch adds css->id which is a subsystem-unique ID and converts css_from_id() to look up by the new css->id instead. memcg is the only user of css_from_id() and also converted to use css->id instead. For traditional hierarchies, this shouldn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jianyu Zhan <nasa4836@gmail.com> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-04cgroup, memcg: allocate cgroup ID from 1Tejun Heo1-2/+2
Currently, cgroup->id is allocated from 0, which is always assigned to the root cgroup; unfortunately, memcg wants to use ID 0 to indicate invalid IDs and ends up incrementing all IDs by one. It's reasonable to reserve 0 for special purposes. This patch updates cgroup core so that ID 0 is not used and the root cgroups get ID 1. The ID incrementing is removed form memcg. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Li Zefan <lizefan@huawei.com>