- 18 11月, 2014 4 次提交
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NZefan Li <lizefan@huawei.com>
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由 Tejun Heo 提交于
When a subsystem is offlined, its entry on @cgrp->subsys[] is cleared asynchronously. If cgroup_subtree_control_write() is requested to enable the subsystem again before the entry is cleared, it has to wait for the previous offlining to finish and clear the @cgrp->subsys[] entry before trying to enable the subsystem again. This is currently done while verifying the input enable / disable parameters. This used to be correct but f63070d3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") breaks it. The commit is one of the commits implementing subsystem dependency. Through subsystem dependency, some subsystems may be enabled and disabled implicitly in addition to the explicitly requested ones. The actual subsystems to be enabled and disabled are determined during @css_enable/disable calculation. The current offline wait logic skips the ones which are already implicitly enabled and then waits for subsystems in @enable; however, this misses the subsystems which may be implicitly enabled through dependency from @enable. If such implicitly subsystem hasn't yet finished offlining yet, the function ends up trying to create a css when its @cgrp->subsys[] slot is already occupied triggering BUG_ON() in init_and_link_css(). Fix it by moving the wait logic after @css_enable is calculated and waiting for all the subsystems in @css_enable. This fixes the above bug as the mask contains all subsystems which are to be enabled including the ones enabled through dependencies. Signed-off-by: NTejun Heo <tj@kernel.org> Fixes: f63070d3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") Acked-by: NZefan Li <lizefan@huawei.com>
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由 Tejun Heo 提交于
Make cgroup_subtree_control_write() first calculate new subtree_control (new_sc), child_subsys_mask (new_ss) and css_enable/disable masks before applying them to the cgroup. Also, store the original subtree_control (old_sc) and child_subsys_mask (old_ss) and use them to restore the orignal state after failure. This patch shouldn't cause any behavior changes. This prepares for a fix for a bug in the async css offline wait logic. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NZefan Li <lizefan@huawei.com>
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由 Tejun Heo 提交于
cgroup_refresh_child_subsys_mask() calculates and updates the effective @cgrp->child_subsys_maks according to the current @cgrp->subtree_control. Separate out the calculation part into cgroup_calc_child_subsys_mask(). This will be used to fix a bug in the async css offline wait logic. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NZefan Li <lizefan@huawei.com>
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- 26 9月, 2014 1 次提交
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由 Zefan Li 提交于
This reverts commit 0c7bf3e8. If there are child cgroups in the cgroupfs and then we umount it, the superblock will be destroyed but the cgroup_root will be kept around. When we mount it again, cgroup_mount() will find this cgroup_root and allocate a new sb for it. So with this commit we will be trapped in a dead loop in the case described above, because kernfs_pin_sb() keeps returning NULL. Currently I don't see how we can avoid using both pinned_sb and new_sb, so just revert it. Cc: Al Viro <viro@ZenIV.linux.org.uk> Reported-by: NAndrey Wagin <avagin@gmail.com> Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 25 9月, 2014 1 次提交
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由 Tejun Heo 提交于
With the recent addition of percpu_ref_reinit(), percpu_ref now can be used as a persistent switch which can be turned on and off repeatedly where turning off maps to killing the ref and waiting for it to drain; however, there currently isn't a way to initialize a percpu_ref in its off (killed and drained) state, which can be inconvenient for certain persistent switch use cases. Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic selection of operation mode; however, currently a newly initialized percpu_ref is always in percpu mode making it impossible to avoid the latency overhead of switching to atomic mode. This patch adds @flags to percpu_ref_init() and implements the following flags. * PERCPU_REF_INIT_ATOMIC : start ref in atomic mode * PERCPU_REF_INIT_DEAD : start ref killed and drained These flags should be able to serve the above two use cases. v2: target_core_tpg.c conversion was missing. Fixed. Signed-off-by: NTejun Heo <tj@kernel.org> Reviewed-by: NKent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org>
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- 21 9月, 2014 2 次提交
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由 Zefan Li 提交于
Both pinned_sb and new_sb indicate if a new superblock is needed, so we can just remove new_sb. Note now we must check if kernfs_tryget_sb() returns NULL, because when it returns NULL, kernfs_mount() may still re-use an existing superblock, which is just allocated by another concurent mount. Suggested-by: NTejun Heo <tj@kernel.org> Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Zefan Li 提交于
The patch 971ff493: "cgroup: use a per-cgroup work for release agent" from Sep 18, 2014, leads to the following static checker warning: kernel/cgroup.c:5310 cgroup_release_agent() warn: 'mutex:&cgroup_mutex' is sometimes locked here and sometimes unlocked. Reported-by: NDan Carpenter <dan.carpenter@oracle.com> Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 19 9月, 2014 4 次提交
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由 Zefan Li 提交于
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: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Zefan Li 提交于
Use the ONE macro instead of REG, and we can simplify proc_cgroup_show(). Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Zefan Li 提交于
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: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Zefan Li 提交于
cgroup_pidlist_start() holds cgrp->pidlist_mutex and then calls pidlist_array_load(), and cgroup_pidlist_stop() releases the mutex. It is wrong that we release the mutex in the failure path in pidlist_array_load(), because cgroup_pidlist_stop() will be called no matter if cgroup_pidlist_start() returns errno or not. Fixes: 4bac00d1 Cc: <stable@vger.kernel.org> # 3.14+ Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NCong Wang <xiyou.wangcong@gmail.com>
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- 18 9月, 2014 3 次提交
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由 Li Zefan 提交于
We never grab cgroup mutex in fork and exit paths no matter whether notify_on_release is set or not. Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Li Zefan 提交于
We no longer clear kn->priv in cgroup_rmdir(), so we don't need to get an extra refcnt. Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Li Zefan 提交于
Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 08 9月, 2014 1 次提交
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由 Tejun Heo 提交于
Percpu allocator now supports allocation mask. Add @gfp to percpu_ref_init() so that !GFP_KERNEL allocation masks can be used with percpu_refs too. This patch doesn't make any functional difference. v2: blk-mq conversion was missing. Updated. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Kent Overstreet <koverstreet@google.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Jens Axboe <axboe@kernel.dk>
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- 05 9月, 2014 2 次提交
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由 Li Zefan 提交于
When cgroup_kn_lock_live() is called through some kernfs operation and another thread is calling cgroup_rmdir(), we'll trigger the warning in cgroup_get(). ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1228 at kernel/cgroup.c:1034 cgroup_get+0x89/0xa0() ... Call Trace: [<c16ee73d>] dump_stack+0x41/0x52 [<c10468ef>] warn_slowpath_common+0x7f/0xa0 [<c104692d>] warn_slowpath_null+0x1d/0x20 [<c10bb999>] cgroup_get+0x89/0xa0 [<c10bbe58>] cgroup_kn_lock_live+0x28/0x70 [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230 [<c10be5b2>] cgroup_tasks_write+0x12/0x20 [<c10bb7b0>] cgroup_file_write+0x40/0x130 [<c11aee71>] kernfs_fop_write+0xd1/0x160 [<c1148e58>] vfs_write+0x98/0x1e0 [<c114934d>] SyS_write+0x4d/0xa0 [<c16f656b>] sysenter_do_call+0x12/0x12 ---[ end trace 6f2e0c38c2108a74 ]--- Fix this by calling css_tryget() instead of cgroup_get(). v2: - move cgroup_tryget() right below cgroup_get() definition. (Tejun) Cc: <stable@vger.kernel.org> # 3.15+ Reported-by: NToralf Förster <toralf.foerster@gmx.de> Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Li Zefan 提交于
Run these two scripts concurrently: for ((; ;)) { mkdir /cgroup/sub rmdir /cgroup/sub } for ((; ;)) { echo $$ > /cgroup/sub/cgroup.procs echo $$ > /cgroup/cgroup.procs } A kernel bug will be triggered: BUG: unable to handle kernel NULL pointer dereference at 00000038 IP: [<c10bbd69>] cgroup_put+0x9/0x80 ... Call Trace: [<c10bbe19>] cgroup_kn_unlock+0x39/0x50 [<c10bbe91>] cgroup_kn_lock_live+0x61/0x70 [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230 [<c10be5b2>] cgroup_tasks_write+0x12/0x20 [<c10bb7b0>] cgroup_file_write+0x40/0x130 [<c11aee71>] kernfs_fop_write+0xd1/0x160 [<c1148e58>] vfs_write+0x98/0x1e0 [<c114934d>] SyS_write+0x4d/0xa0 [<c16f656b>] sysenter_do_call+0x12/0x12 We clear cgrp->kn->priv in the end of cgroup_rmdir(), but another concurrent thread can access kn->priv after the clearing. We should move the clearing to css_release_work_fn(). At that time no one is holding reference to the cgroup and no one can gain a new reference to access it. v2: - move RCU_INIT_POINTER() into the else block. (Tejun) - remove the cgroup_parent() check. (Tejun) - update the comment in css_tryget_online_from_dir(). Cc: <stable@vger.kernel.org> # 3.15+ Reported-by: NToralf Förster <toralf.foerster@gmx.de> Signed-off-by: NZefan Li <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 25 8月, 2014 1 次提交
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由 Dongsheng Yang 提交于
There is no function named cgroup_enable_task_cg_links(). Instead, the correct function name in this comment should be cgroup_enabled_task_cg_lists(). Signed-off-by: NDongsheng Yang <yangds.fnst@cn.fujitsu.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 23 8月, 2014 1 次提交
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由 Vivek Goyal 提交于
Kernel command line parameter cgroup__DEVEL__legacy_files_on_dfl forces legacy cgroup files to show up on default hierarhcy if susbsystem does not have any files defined for default hierarchy. But this seems to be working only if legacy files are defined in ss->legacy_cftypes. If one adds some cftypes later using cgroup_add_legacy_cftypes(), these files don't show up on default hierarchy. Update the function accordingly so that the dynamically added legacy files also show up in the default hierarchy if the target subsystem is also using the base legacy files for the default hierarchy. tj: Patch description and comment updates. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 18 8月, 2014 1 次提交
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由 Alban Crequy 提交于
/proc/<pid>/cgroup contains one cgroup path on each line. If cgroup names are allowed to contain "\n", applications cannot parse /proc/<pid>/cgroup safely. Signed-off-by: NAlban Crequy <alban.crequy@collabora.co.uk> Signed-off-by: NTejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org
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- 15 7月, 2014 6 次提交
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由 Tejun Heo 提交于
cgrp_dfl_root_inhibit_ss_mask determines which subsystems are not supported on the default hierarchy and is currently initialized statically and just includes the debug subsystem. Now that there's cgroup_subsys->dfl_files, we can easily tell which subsystems support the default hierarchy or not. Let's initialize cgrp_dfl_root_inhibit_ss_mask by testing whether cgroup_subsys->dfl_files is NULL. After all, subsystems with NULL ->dfl_files aren't useable on the default hierarchy anyway. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NNeil Horman <nhorman@tuxdriver.com> Acked-by: NLi 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>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NNeil Horman <nhorman@tuxdriver.com> Acked-by: NLi 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>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NNeil Horman <nhorman@tuxdriver.com> Acked-by: NLi 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>
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由 Tejun Heo 提交于
Currently cgroup_base_files[] contains the cgroup core interface files for both legacy and default hierarchies with each file tagged with CFTYPE_INSANE and CFTYPE_ONLY_ON_DFL. This is difficult to read. Let's separate it out to two separate tables, cgroup_dfl_base_files[] and cgroup_legacy_base_files[], and use the appropriate one in cgroup_mkdir() depending on the hierarchy type. This makes tagging each file unnecessary. This patch doesn't introduce any behavior changes. v2: cgroup_dfl_base_files[] was missing the termination entry triggering WARN in cgroup_init_cftypes() for 0day kernel testing robot. Fixed. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Cc: Jet Chen <jet.chen@intel.com>
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- 09 7月, 2014 9 次提交
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由 Tejun Heo 提交于
After the previous patch to remove sane_behavior support from non-default hierarchies, CGRP_ROOT_SANE_BEHAVIOR is used only to indicate the default hierarchy while parsing mount options. This patch makes the following cleanups around it. * Don't show it in the mount option. Eventually the default hierarchy will be assigned a different filesystem type. * As sane_behavior is no longer effective on non-default hierarchies and the default hierarchy doesn't accept any mount options, parse_cgroupfs_options() can consider sane_behavior mount option as indicating the default hierarchy and fail if any other options are specified with it. While at it, remove one of the double blank lines in the function. * cgroup_mount() can now simply test CGRP_ROOT_SANE_BEHAVIOR to tell whether to mount the default hierarchy or not. * As CGROUP_ROOT_SANE_BEHAVIOR's only role now is indicating whether to select the default hierarchy or not during mount, it doesn't need to be set in the default hierarchy itself. cgroup_init_early() updated accordingly. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NVivek Goyal <vgoyal@redhat.com> Acked-by: NLi Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz>
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由 Tejun Heo 提交于
"cgroup.sane_behavior" is added to help distinguishing whether sane_behavior is in effect or not. We now have the default hierarchy where the flag is always in effect and are planning to remove supporting sane behavior on the legacy hierarchies making this file on the default hierarchy rather pointless. Let's make it legacy only and thus always zero. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
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由 Tejun Heo 提交于
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: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
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由 Tejun Heo 提交于
Make the following two reorganizations to cgroup_subtree_control_write(). These are to prepare for future changes and shouldn't cause any functional difference. * Move availability above css offlining wait. * Move cgrp->child_subsys_mask update above new css creation. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NLi Zefan <lizefan@huawei.com> Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
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- 30 6月, 2014 2 次提交
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由 Li Zefan 提交于
We've converted cgroup to kernfs so cgroup won't be intertwined with vfs objects and locking, but there are dark areas. Run two instances of this script concurrently: for ((; ;)) { mount -t cgroup -o cpuacct xxx /cgroup umount /cgroup } After a while, I saw two mount processes were stuck at retrying, because they were waiting for a subsystem to become free, but the root associated with this subsystem never got freed. This can happen, if thread A is in the process of killing superblock but hasn't called percpu_ref_kill(), and at this time thread B is mounting the same cgroup root and finds the root in the root list and performs percpu_ref_try_get(). To fix this, we try to increase both the refcnt of the superblock and the percpu refcnt of cgroup root. v2: - we should try to get both the superblock refcnt and cgroup_root refcnt, because cgroup_root may have no superblock assosiated with it. - adjust/add comments. tj: Updated comments. Renamed @sb to @pinned_sb. Cc: <stable@vger.kernel.org> # 3.15 Signed-off-by: NLi Zefan <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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由 Li Zefan 提交于
# cat test.sh #! /bin/bash mount -t cgroup -o cpu xxx /cgroup umount /cgroup mount -t cgroup -o cpu,cpuacct xxx /cgroup umount /cgroup # ./test.sh mount: xxx already mounted or /cgroup busy mount: according to mtab, xxx is already mounted on /cgroup It's because the cgroupfs_root of the first mount was under destruction asynchronously. Fix this by delaying and then retrying mount for this case. v3: - put the refcnt immediately after getting it. (Tejun) v2: - use percpu_ref_tryget_live() rather that introducing percpu_ref_alive(). (Tejun) - adjust comment. tj: Updated the comment a bit. Cc: <stable@vger.kernel.org> # 3.15 Signed-off-by: NLi Zefan <lizefan@huawei.com> Signed-off-by: NTejun Heo <tj@kernel.org>
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- 28 6月, 2014 1 次提交
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由 Tejun Heo 提交于
Currently, a percpu_ref undoes percpu_ref_init() automatically by freeing the allocated percpu area when the percpu_ref is killed. While seemingly convenient, this has the following niggles. * It's impossible to re-init a released reference counter without going through re-allocation. * In the similar vein, it's impossible to initialize a percpu_ref count with static percpu variables. * We need and have an explicit destructor anyway for failure paths - percpu_ref_cancel_init(). This patch removes the automatic percpu counter freeing in percpu_ref_kill_rcu() and repurposes percpu_ref_cancel_init() into a generic destructor now named percpu_ref_exit(). percpu_ref_destroy() is considered but it gets confusing with percpu_ref_kill() while "exit" clearly indicates that it's the counterpart of percpu_ref_init(). All percpu_ref_cancel_init() users are updated to invoke percpu_ref_exit() instead and explicit percpu_ref_exit() calls are added to the destruction path of all percpu_ref users. Signed-off-by: NTejun Heo <tj@kernel.org> Acked-by: NBenjamin LaHaise <bcrl@kvack.org> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Li Zefan <lizefan@huawei.com>
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- 18 6月, 2014 1 次提交
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由 Li Zefan 提交于
After running: # mount -t cgroup cpu xxx /cgroup && mkdir /cgroup/sub && \ rmdir /cgroup/sub && umount /cgroup I found the cgroup root still existed: # cat /proc/cgroups #subsys_name hierarchy num_cgroups enabled cpuset 0 1 1 cpu 1 1 1 ... It turned out css_has_online_children() is broken. Signed-off-by: NLi Zefan <lizefan@huawei.com> Sigend-off-by: NTejun Heo <tj@kernel.org>
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