Pull cgroup fix from Tejun Heo:
"Fix for a minor memory leak bug in the cgroup init failure path"
* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: fix a leak when percpu_ref_init() fails
Pull cgroup changes from Tejun Heo:
"This contains two patches, both of which aren't fixes per-se but I
think it'd be better to fast-track them.
One removes bcache_subsys_id which was added without proper review
through the block tree. Fortunately, bcache cgroup code is
unconditionally disabled, so this was never exposed to userland. The
cgroup subsys_id is removed. Kent will remove the affected (disabled)
code through bcache branch.
The other simplifies task_group_path_from_hierarchy(). The function
doesn't currently have in-kernel users but there are external code and
development going on dependent on the function and making the function
available for 3.11 would make things go smoother"
* 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: replace task_cgroup_path_from_hierarchy() with task_cgroup_path()
cgroup: remove bcache_subsys_id which got added stealthily
task_cgroup_path_from_hierarchy() was added for the planned new users
and none of the currently planned users wants to know about multiple
hierarchies. This patch drops the multiple hierarchy part and makes
it always return the path in the first non-dummy hierarchy.
As unified hierarchy will always have id 1, this is guaranteed to
return the path for the unified hierarchy if mounted; otherwise, it
will return the path from the hierarchy which happens to occupy the
lowest hierarchy id, which will usually be the first hierarchy mounted
after boot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Jan Kaluža <jkaluza@redhat.com>
0ce6cba357 ("cgroup: CGRP_ROOT_SUBSYS_BOUND should be ignored when
comparing mount options") only updated the remount path but
CGRP_ROOT_SUBSYS_BOUND should also be ignored when comparing options
while mounting an existing hierarchy. As option mismatch triggers a
warning but doesn't fail the mount without sane_behavior, this only
triggers a spurious warning message.
Fix it by only comparing CGRP_ROOT_OPTION_MASK bits when comparing new
and existing root options.
Signed-off-by: Tejun Heo <tj@kernel.org>
1672d04070 ("cgroup: fix cgroupfs_root early destruction path")
introduced CGRP_ROOT_SUBSYS_BOUND which is used to mark completion of
subsys binding on a new root; however, this broke remounts.
cgroup_remount() doesn't allow changing root options via remount and
CGRP_ROOT_SUBSYS_BOUND, which is set on all fully initialized roots,
makes the function reject all remounts.
Fix it by putting the options part in the lower 16 bits of root->flags
and masking the comparions. While at it, make cgroup_remount() emit
an error message explaining why it's rejecting a remount request, so
that it's less of a mystery.
Signed-off-by: Tejun Heo <tj@kernel.org>
kernel/cgroup.c still has places where a RCU pointer is set and
accessed directly without going through RCU_INIT_POINTER() or
rcu_dereference_protected(). They're all properly protected accesses
so nothing is broken but it leads to spurious sparse RCU address space
warnings.
Substitute direct accesses with RCU_INIT_POINTER() and
rcu_dereference_protected(). Note that %true is specified as the
extra condition for all derference updates. This isn't ideal as all
it does is suppressing warning without actually policing
synchronization rules; however, most are scheduled to be removed
pretty soon along with css_id itself, so no reason to be more
elaborate.
Combined with the previous changes, this removes all RCU related
sparse warnings from cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by; Li Zefan <lizefan@huawei.com>
There are several places in kernel/cgroup.c where task->cgroups is
accessed and modified without going through proper RCU accessors.
None is broken as they're all lock protected accesses; however, this
still triggers sparse RCU address space warnings.
* Consistently use task_css_set() for task->cgroups dereferencing.
* Use RCU_INIT_POINTER() to clear task->cgroups to &init_css_set on
exit.
* Remove unnecessary rcu_dereference_raw() from cset->subsys[]
dereference in cgroup_exit().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Li Zefan <lizefan@huawei.com>
This isn't strictly necessary as all subsystems specified in
@subsys_mask are guaranteed to be pinned; however, it does spuriously
trigger lockdep warning. Let's grab cgroup_mutex around it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroupfs_root used to have ->actual_subsys_mask in addition to
->subsys_mask. a8a648c4ac ("cgroup: remove
cgroup->actual_subsys_mask") removed it noting that the subsys_mask is
essentially temporary and doesn't belong in cgroupfs_root; however,
the patch made it impossible to tell whether a cgroupfs_root actually
has the subsystems bound or just have the bits set leading to the
following BUG when trying to mount with subsystems which are already
mounted elsewhere.
kernel BUG at kernel/cgroup.c:1038!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
...
CPU: 1 PID: 7973 Comm: mount Tainted: G W 3.10.0-rc7-next-20130625-sasha-00011-g1c1dc0e #1105
task: ffff880fc0ae8000 ti: ffff880fc0b9a000 task.ti: ffff880fc0b9a000
RIP: 0010:[<ffffffff81249b29>] [<ffffffff81249b29>] rebind_subsystems+0x409/0x5f0
...
Call Trace:
[<ffffffff8124bd4f>] cgroup_kill_sb+0xff/0x210
[<ffffffff813d21af>] deactivate_locked_super+0x4f/0x90
[<ffffffff8124f3b3>] cgroup_mount+0x673/0x6e0
[<ffffffff81257169>] cpuset_mount+0xd9/0x110
[<ffffffff813d2580>] mount_fs+0xb0/0x2d0
[<ffffffff81404afd>] vfs_kern_mount+0xbd/0x180
[<ffffffff814070b5>] do_new_mount+0x145/0x2c0
[<ffffffff814085d6>] do_mount+0x356/0x3c0
[<ffffffff8140873d>] SyS_mount+0xfd/0x140
[<ffffffff854eb600>] tracesys+0xdd/0xe2
We still want rebind_subsystems() to take added/removed masks, so
let's fix it by marking whether a cgroupfs_root has finished binding
or not. Also, document what's going on around ->subsys_mask
initialization so that similar mistakes aren't repeated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Before 1a57423166 ("cgroup: make hierarchy_id use cyclic idr"),
hierarchy IDs were allocated from 0. As the dummy hierarchy was
always the one first initialized, it got assigned 0 and all other
hierarchies from 1. The patch accidentally changed the minimum
useable ID to 2.
Let's restore ID 0 for dummy_root and while at it reserve 1 for
unified hierarchy.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
There are quite a few places where all loaded [builtin] subsys are
iterated. Implement for_each_[builtin_]subsys() and replace manual
iterations with those to simplify those places a bit. The new
iterators automatically skip NULL subsystems. This shouldn't cause
any functional difference.
Iteration loops which scan all subsystems and then skipping modular
ones explicitly are converted to use for_each_builtin_subsys().
While at it, reorder variable declarations and adjust whitespaces a
bit in the affected functions.
v2: Add lockdep_assert_held() in for_each_subsys() and add comments
about synchronization as suggested by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_init() was doing init_css_set initialization outside
cgroup_mutex, which is fine but we want to add lockdep annotation on
subsystem iterations and cgroup_init() will trigger it spuriously.
Move init_css_set initialization inside cgroup_mutex.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
for_each_subsys() walks over subsystems attached to a hierarchy and
we're gonna add iterators which walk over all available subsystems.
Rename for_each_subsys() to for_each_root_subsys() so that it's more
appropriately named and for_each_subsys() can be used to iterate all
subsystems.
While at it, remove unnecessary underbar prefix from macro arguments,
put them inside parentheses, and adjust indentation for the two
for_each_*() macros.
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
find_css_set() passes uninitialized on-stack template[] array to
find_existing_css_set() which sets the entries for all subsystems.
Passing around an uninitialized array is a bit icky and we want to
introduce an iterator which only iterates loaded subsystems. Let's
initialize it on definition.
While at it, also make the following cosmetic cleanups.
* Convert to proper /** comments.
* Reorder variable declarations.
* Replace comment on synchronization with lockdep_assert_held().
This patch doesn't make any functional differences.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup curiously has two subsystem masks, ->subsys_mask and
->actual_subsys_mask. The latter only exists because the new target
subsys_mask is passed into rebind_subsystems() via @root>subsys_mask.
rebind_subsystems() needs to know what the current mask is to decide
how to reach the target mask so ->actual_subsys_mask is used as the
temp location to remember the current state.
Adding a temporary field to a permanent data structure is rather silly
and can be misleading. Update rebind_subsystems() to take @added_mask
and @removed_mask instead and remove @root->actual_subsys_mask.
This patch shouldn't introduce any behavior changes.
v2: Comment and description updated as suggested by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Global variable names in kernel/cgroup.c are asking for trouble -
subsys, roots, rootnode and so on. Rename them to have "cgroup_"
prefix.
* s/subsys/cgroup_subsys/
* s/rootnode/cgroup_dummy_root/
* s/dummytop/cgroup_cummy_top/
* s/roots/cgroup_roots/
* s/root_count/cgroup_root_count/
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cont is short for container. control group was named process container
at first, but then people found container already has a meaning in
linux kernel.
Clean up the leftover variable name @cont.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup_serial_nr_cursor was created atomic64_t because I thought it
was never gonna used for anything other than assigning unique numbers
to cgroups and didn't want to worry about synchronization; however,
now we're using it as an event-stamp to distinguish cgroups created
before and after certain point which assumes that it's protected by
cgroup_mutex.
Let's make it clear by making it a u64. Also, rename it to
cgroup_serial_nr_next and make it point to the next nr to allocate so
that where it's pointing to is clear and more conventional.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
We used root->allcg_list to iterate cgroup hierarchy because at that time
cgroup_for_each_descendant_pre() hasn't been invented.
tj: In cgroup_cfts_commit(), s/@serial_nr/@update_upto/, move the
assignment right above releasing cgroup_mutex and explain what's
going on there.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The next patch will use it to determine if a cgroup is newly created
while we're iterating the cgroup hierarchy.
tj: Rephrased the comment on top of cgroup_serial_nr_cursor.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The memory allocated in cgroup_add_cftypes() should be freed. The
effect of this bug is we leak a bit memory everytime we unload
cfq-iosched module if blkio cgroup is enabled.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
commit 5db9a4d99b
Author: Tejun Heo <tj@kernel.org>
Date: Sat Jul 7 16:08:18 2012 -0700
cgroup: fix cgroup hierarchy umount race
This commit fixed a race caused by the dput() in css_dput_fn(), but
the dput() in cgroup_event_remove() can also lead to the same BUG().
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
