Impact: New perf_counter features
This primarily adds a way for perf_counter users to enable and disable
counters and groups. Enabling or disabling a counter or group also
enables or disables all of the child counters that have been cloned
from it to monitor children of the task monitored by the top-level
counter. The userspace interface to enable/disable counters is via
ioctl on the counter file descriptor.
Along the way this extends the code that handles child counters to
handle child counter groups properly. A group with multiple counters
will be cloned to child tasks if and only if the group leader has the
hw_event.inherit bit set - if it is set the whole group is cloned as a
group in the child task.
In order to be able to enable or disable all child counters of a given
top-level counter, we need a way to find them all. Hence I have added
a child_list field to struct perf_counter, which is the head of the
list of children for a top-level counter, or the link in that list for
a child counter. That list is protected by the perf_counter.mutex
field.
This also adds a mutex to the perf_counter_context struct. Previously
the list of counters was protected just by the lock field in the
context, which meant that perf_counter_init_task had to take that lock
and then take whatever lock/mutex protects the top-level counter's
child_list. But the counter enable/disable functions need to take
that lock in order to traverse the list, then for each counter take
the lock in that counter's context in order to change the counter's
state safely, which will lead to a deadlock.
To solve this, we now have both a mutex and a spinlock in the context,
and taking either is sufficient to ensure the list of counters can't
change - you have to take both before changing the list. Now
perf_counter_init_task takes the mutex instead of the lock (which
incidentally means that inherit_counter can use GFP_KERNEL instead of
GFP_ATOMIC) and thus avoids the possible deadlock. Similarly the new
enable/disable functions can take the mutex while traversing the list
of child counters without incurring a possible deadlock when the
counter manipulation code locks the context for a child counter.
We also had an misfeature that the first counter added to a context
would possibly not go on until the next sched-in, because we were
using ctx->nr_active to detect if the context was running on a CPU.
But nr_active is the number of active counters, and if that was zero
(because the context didn't have any counters yet) it would look like
the context wasn't running on a cpu and so the retry code in
__perf_install_in_context wouldn't retry. So this adds an 'is_active'
field that is set when the context is on a CPU, even if it has no
counters. The is_active field is only used for task contexts, not for
per-cpu contexts.
If we enable a subsidiary counter in a group that is active on a CPU,
and the arch code can't enable the counter, then we have to pull the
whole group off the CPU. We do this with group_sched_out, which gets
moved up in the file so it comes before all its callers. This also
adds similar logic to __perf_install_in_context so that the "all on,
or none" invariant of groups is preserved when adding a new counter to
a group.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Impact: New perf_counter features
A pinned counter group is one that the user wants to have on the CPU
whenever possible, i.e. whenever the associated task is running, for
a per-task group, or always for a per-cpu group. If the system
cannot satisfy that, it puts the group into an error state where
it is not scheduled any more and reads from it return EOF (i.e. 0
bytes read). The group can be released from error state and made
readable again using prctl(PR_TASK_PERF_COUNTERS_ENABLE). When we
have finer-grained enable/disable controls on counters we'll be able
to reset the error state on individual groups.
An exclusive group is one that the user wants to be the only group
using the CPU performance monitor hardware whenever it is on. The
counter group scheduler will not schedule an exclusive group if there
are already other groups on the CPU and will not schedule other groups
onto the CPU if there is an exclusive group scheduled (that statement
does not apply to groups containing only software counters, which can
always go on and which do not prevent an exclusive group from going on).
With an exclusive group, we will be able to let users program PMU
registers at a low level without the concern that those settings will
perturb other measurements.
Along the way this reorganizes things a little:
- is_software_counter() is moved to perf_counter.h.
- cpuctx->active_oncpu now records the number of hardware counters on
the CPU, i.e. it now excludes software counters. Nothing was reading
cpuctx->active_oncpu before, so this change is harmless.
- A new cpuctx->exclusive field records whether we currently have an
exclusive group on the CPU.
- counter_sched_out moves higher up in perf_counter.c and gets called
from __perf_counter_remove_from_context and __perf_counter_exit_task,
where we used to have essentially the same code.
- __perf_counter_sched_in now goes through the counter list twice, doing
the pinned counters in the first loop and the non-pinned counters in
the second loop, in order to give the pinned counters the best chance
to be scheduled in.
Note that only a group leader can be exclusive or pinned, and that
attribute applies to the whole group. This avoids some awkwardness in
some corner cases (e.g. where a group leader is closed and the other
group members get added to the context list). If we want to relax that
restriction later, we can, and it is easier to relax a restriction than
to apply a new one.
This doesn't yet handle the case where a pinned counter is inherited
and goes into error state in the child - the error state is not
propagated up to the parent when the child exits, and arguably it
should.
Signed-off-by: Paul Mackerras <paulus@samba.org>
This makes sure that we call the platform-specific ppc_md.enable_pmcs
function on each CPU before we try to use the PMU on that CPU. If the
CPU goes off-line and then on-line, we need to do the enable_pmcs call
again, so we use the hw_perf_counter_setup hook to ensure that. It gets
called as each CPU comes online, but it isn't called on the CPU that is
coming up, so this adds the CPU number as an argument to it (there were
no non-empty instances of hw_perf_counter_setup before).
This also arranges to set the pmcregs_in_use field of the lppaca (data
structure shared with the hypervisor) on each CPU when we are using the
PMU and clear it when we are not. This allows the hypervisor to optimize
partition switches by not saving/restoring the PMU registers when we
aren't using the PMU.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Software counters aren't subject to the limitations imposed by the
fixed number of hardware counter registers, so there is no reason not
to enable them all in __perf_counter_sched_in. Previously we used to
break out of the loop when we got to a group that wouldn't fit on the
PMU; with this we continue through the list but only schedule in
software counters (or groups containing only software counters) from
there on.
Signed-off-by: Paul Mackerras <paulus@samba.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/arjan/linux-2.6-async-2:
async: make async a command line option for now
partial revert of asynchronous inode delete
* git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-2.6-nommu:
NOMMU: Support XIP on initramfs
NOMMU: Teach kobjsize() about VMA regions.
FLAT: Don't attempt to expand the userspace stack to fill the space allocated
FDPIC: Don't attempt to expand the userspace stack to fill the space allocated
NOMMU: Improve procfs output using per-MM VMAs
NOMMU: Make mmap allocation page trimming behaviour configurable.
NOMMU: Make VMAs per MM as for MMU-mode linux
NOMMU: Delete askedalloc and realalloc variables
NOMMU: Rename ARM's struct vm_region
NOMMU: Fix cleanup handling in ramfs_nommu_get_umapped_area()
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile: (31 commits)
powerpc/oprofile: fix whitespaces in op_model_cell.c
powerpc/oprofile: IBM CELL: add SPU event profiling support
powerpc/oprofile: fix cell/pr_util.h
powerpc/oprofile: IBM CELL: cleanup and restructuring
oprofile: make new cpu buffer functions part of the api
oprofile: remove #ifdef CONFIG_OPROFILE_IBS in non-ibs code
ring_buffer: fix ring_buffer_event_length()
oprofile: use new data sample format for ibs
oprofile: add op_cpu_buffer_get_data()
oprofile: add op_cpu_buffer_add_data()
oprofile: rework implementation of cpu buffer events
oprofile: modify op_cpu_buffer_read_entry()
oprofile: add op_cpu_buffer_write_reserve()
oprofile: rename variables in add_ibs_begin()
oprofile: rename add_sample() in cpu_buffer.c
oprofile: rename variable ibs_allowed to has_ibs in op_model_amd.c
oprofile: making add_sample_entry() inline
oprofile: remove backtrace code for ibs
oprofile: remove unused ibs macro
oprofile: remove unused components in struct oprofile_cpu_buffer
...
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (94 commits)
ACPICA: hide private headers
ACPICA: create acpica/ directory
ACPI: fix build warning
ACPI : Use RSDT instead of XSDT by adding boot option of "acpi=rsdt"
ACPI: Avoid array address overflow when _CST MWAIT hint bits are set
fujitsu-laptop: Simplify SBLL/SBL2 backlight handling
fujitsu-laptop: Add BL power, LED control and radio state information
ACPICA: delete utcache.c
ACPICA: delete acdisasm.h
ACPICA: Update version to 20081204.
ACPICA: FADT: Update error msgs for consistency
ACPICA: FADT: set acpi_gbl_use_default_register_widths to TRUE by default
ACPICA: FADT parsing changes and fixes
ACPICA: Add ACPI_MUTEX_TYPE configuration option
ACPICA: Fixes for various ACPI data tables
ACPICA: Restructure includes into public/private
ACPI: remove private acpica headers from driver files
ACPI: reboot.c: use new acpi_reset interface
ACPICA: New: acpi_reset interface - write to reset register
ACPICA: Move all public H/W interfaces to new hwxface
...
The newly allocated creds in prepare_kernel_cred() must be initialised
before get_uid() and get_group_info() can access them. They should be
copied from the old credentials.
Reported-by: Steve Dickson <steved@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: minimize requirements on architectures
Currently, an architecture just enabling CONFIG_PERF_COUNTERS but not
providing any extra functions will fail to build with
perf_counter_print_debug being undefined, since we don't provide an
empty dummy definition like we do with the hw_perf_* functions.
This provides an empty dummy perf_counter_print_debug() to make it
easier for architectures to turn on CONFIG_PERF_COUNTERS.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Impact: extend perf_counter infrastructure
This adds an optional hw_perf_group_sched_in() arch function that enables
a whole group of counters in one go. It returns 1 if it added the group
successfully, 0 if it did nothing (and therefore the core needs to add
the counters individually), or a negative number if an error occurred.
It should add all the counters and enable any software counters in the
group, or else add none of them and return an error.
There are a couple of related changes/improvements in the group handling
here:
* As an optimization, group_sched_out() and group_sched_in() now check the
state of the group leader, and do nothing if the leader is not active
or disabled.
* We now call hw_perf_save_disable/hw_perf_restore around the complete
set of counter enable/disable calls in __perf_counter_sched_in/out,
to give the arch code the opportunity to defer updating the hardware
state until the hw_perf_restore call if it wants.
* We no longer stop adding groups after we get to a group that has more
than one counter. We will ultimately add an option for a group to be
exclusive. The current code doesn't really implement exclusive groups
anyway, since a group could end up going on with other counters that
get added before it.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Impact: bug fix
Currently if you do (e.g.) timec -e -1 ls, it will report 0 for the
value of the cpu_clock counter. The reason is that the core assumes
that a counter's count field is up-to-date when the counter is inactive,
and doesn't call the counter's read function. However, the cpu_clock
counter code only updates the count in the read function.
This fixes it by making both the read and disable functions update the
count. It also makes the counter ignore time passing while the counter
is disabled, by making the enable function update the hw.prev_count field.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Impact: fix oops-causing bug
Currently, if you try to use perf_counters on an architecture that has
no hardware support, and you select an event that doesn't map to any of
the defined software counters, you get an oops rather than an error.
This is because the dummy hw_perf_counter_init returns ERR_PTR(-EINVAL)
but the caller (perf_counter_alloc) only tests for NULL.
This makes the dummy hw_perf_counter_init return NULL instead.
Signed-off-by: Paul Mackerras <paulus@samba.org>
turns out that there are real problems with allowing async
tasks that are scheduled from async tasks to run after
the async_synchronize_full() returns.
This patch makes the _full more strict and a complete
synchronization. Later I might need to add back a lighter
form of synchronization for other uses.. but not right now.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently task_active_pid_ns is not safe to call after a task becomes a
zombie and exit_task_namespaces is called, as nsproxy becomes NULL. By
reading the pid namespace from the pid of the task we can trivially solve
this problem at the cost of one extra memory read in what should be the
same cacheline as we read the namespace from.
When moving things around I have made task_active_pid_ns out of line
because keeping it in pid_namespace.h would require adding includes of
pid.h and sched.h that I don't think we want.
This change does make task_active_pid_ns unsafe to call during
copy_process until we attach a pid on the task_struct which seems to be a
reasonable trade off.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Bastian Blank <bastian@waldi.eu.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: cleanups, use new cpumask API
Final trivial cleanups: mainly s/cpumask_t/struct cpumask
Note there is a FIXME in generate_sched_domains(). A future patch will
change struct cpumask *doms to struct cpumask *doms[].
(I suppose Rusty will do this.)
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mike Travis <travis@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: use new cpumask API
This patch mainly does the following things:
- change cs->cpus_allowed from cpumask_t to cpumask_var_t
- call alloc_bootmem_cpumask_var() for top_cpuset in cpuset_init_early()
- call alloc_cpumask_var() for other cpusets
- replace cpus_xxx() to cpumask_xxx()
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mike Travis <travis@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: cleanups, reduce stack usage
This patch prepares for the next patch. When we convert
cpuset.cpus_allowed to cpumask_var_t, (trialcs = *cs) no longer works.
Another result of this patch is reducing stack usage of trialcs.
sizeof(*cs) can be as large as 148 bytes on x86_64, so it's really not
good to have it on stack.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mike Travis <travis@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset converts cpuset to use new cpumask API, and thus
remove on stack cpumask_t to reduce stack usage.
Before:
# cat kernel/cpuset.c include/linux/cpuset.h | grep -c cpumask_t
21
After:
# cat kernel/cpuset.c include/linux/cpuset.h | grep -c cpumask_t
0
This patch:
Impact: reduce stack usage
It's safe to call cpulist_scnprintf inside callback_mutex, and thus we can
just remove the cpumask_t and no need to allocate a cpumask_var_t.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mike Travis <travis@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I found a bug on my dual-cpu box. I created a sub cpuset in top cpuset
and assign 1 to its cpus. And then we attach some tasks into this sub
cpuset. After this, we offline CPU1. Now, the tasks in this new cpuset
are moved into top cpuset automatically because there is no cpu in sub
cpuset. Then we online CPU1, we find all the tasks which doesn't belong
to top cpuset originally just run on CPU0.
We fix this bug by setting task's cpu_allowed to cpu_possible_map when
attaching it into top cpuset. This method needn't modify the current
behavior of cpusets on CPU hotplug, and all of tasks in top cpuset use
cpu_possible_map to initialize their cpu_allowed.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
task_cs() calls task_subsys_state().
We must use rcu_read_lock() to protect cgroup_subsys_state().
It's correct that top_cpuset is never freed, but cgroup_subsys_state()
accesses css_set, this css_set maybe freed when task_cs() called.
We use use rcu_read_lock() to protect it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add css_tryget(), that obtains a counted reference on a CSS. It is used
in situations where the caller has a "weak" reference to the CSS, i.e.
one that does not protect the cgroup from removal via a reference count,
but would instead be cleaned up by a destroy() callback.
css_tryget() will return true on success, or false if the cgroup is being
removed.
This is similar to Kamezawa Hiroyuki's patch from a week or two ago, but
with the difference that in the event of css_tryget() racing with a
cgroup_rmdir(), css_tryget() will only return false if the cgroup really
does get removed.
This implementation is done by biasing css->refcnt, so that a refcnt of 1
means "releasable" and 0 means "released or releasing". In the event of a
race, css_tryget() distinguishes between "released" and "releasing" by
checking for the CSS_REMOVED flag in css->flags.
Signed-off-by: Paul Menage <menage@google.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These patches introduce new locking/refcount support for cgroups to
reduce the need for subsystems to call cgroup_lock(). This will
ultimately allow the atomicity of cgroup_rmdir() (which was removed
recently) to be restored.
These three patches give:
1/3 - introduce a per-subsystem hierarchy_mutex which a subsystem can
use to prevent changes to its own cgroup tree
2/3 - use hierarchy_mutex in place of calling cgroup_lock() in the
memory controller
3/3 - introduce a css_tryget() function similar to the one recently
proposed by Kamezawa, but avoiding spurious refcount failures in
the event of a race between a css_tryget() and an unsuccessful
cgroup_rmdir()
Future patches will likely involve:
- using hierarchy mutex in place of cgroup_lock() in more subsystems
where appropriate
- restoring the atomicity of cgroup_rmdir() with respect to cgroup_create()
This patch:
Add a hierarchy_mutex to the cgroup_subsys object that protects changes to
the hierarchy observed by that subsystem. It is taken by the cgroup
subsystem (in addition to cgroup_mutex) for the following operations:
- linking a cgroup into that subsystem's cgroup tree
- unlinking a cgroup from that subsystem's cgroup tree
- moving the subsystem to/from a hierarchy (including across the
bind() callback)
Thus if the subsystem holds its own hierarchy_mutex, it can safely
traverse its own hierarchy.
Signed-off-by: Paul Menage <menage@google.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for building hierarchies in resource counters. Cgroups allows
us to build a deep hierarchy, but we currently don't link the resource
counters belonging to the memory controller control groups, in the same
fashion as the corresponding cgroup entries in the cgroup hierarchy. This
patch provides the infrastructure for resource counters that have the same
hiearchy as their cgroup counter parts.
These set of patches are based on the resource counter hiearchy patches
posted by Pavel Emelianov.
NOTE: Building hiearchies is expensive, deeper hierarchies imply charging
the all the way up to the root. It is known that hiearchies are
expensive, so the user needs to be careful and aware of the trade-offs
before creating very deep ones.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix races between /proc/sched_debug by freeing cgroup objects via an RCU
callback. Thus any cgroup reference obtained from an RCU-safe source will
remain valid during the RCU section. Since dentries are also RCU-safe,
this allows us to traverse up the tree safely.
Additionally, make cgroup_path() check for a NULL cgrp->dentry to avoid
trying to report a path for a partially-created cgroup.
[lizf@cn.fujitsu.com: call deactive_super() in cgroup_diput()]
Signed-off-by: Paul Menage <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Once tasks are populated from system namespace inside cgroup, container
replaces other namespace task with 0 while listing tasks, inside
container.
Though this is expected behaviour from container end, there is no use of
showing unwanted 0s.
In this patch, we check if a process is in same namespace before loading
into pid array.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Gowrishankar M <gowrishankar.m@in.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Though for an inactive hierarchy, we have subsys->root == &rootnode, but
rootnode's subsys_list is always empty.
This conflicts with the code in find_css_set():
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
...
if (ss->root->subsys_list.next == &ss->sibling) {
...
}
}
if (list_empty(&rootnode.subsys_list)) {
...
}
The above code assumes rootnode.subsys_list links all inactive
hierarchies.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cgroup_iter_* do not need rcu_read_lock().
In cgroup_enable_task_cg_lists(), do_each_thread() and while_each_thread()
are protected by RCU, it's OK, for write_lock(&css_set_lock) implies
rcu_read_lock() in non-RT kernel.
If we need explicit rcu_read_lock(), we should add rcu_read_lock() in
cgroup_enable_task_cg_lists(), not cgroup_iter_*.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In cgroup_attach_task(), tsk maybe exit when we call find_css_set(). and
find_css_set() will access to invalid css_set.
This patch increases the count before get_css_set(), and decreases it
after find_css_set().
NOTE:
css_set's refcount is also taskcount, after this patch applied, taskcount
may be off-by-one WHEN cgroup_lock() is not held. but I reviewed other
code which use taskcount, they are still correct. No regression found by
reviewing and simply testing.
So I do not use two counters in css_set. (one counter for taskcount, the
other for refcount. like struct mm_struct) If this fix cause regression,
we will use two counters in css_set.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We don't access struct cgroupfs_root in fast path, so we should not put
struct cgroupfs_root protected by RCU
But the comment in struct cgroup_subsys.root confuse us.
struct cgroup_subsys.root is used in these places:
1 find_css_set(): if (ss->root->subsys_list.next == &ss->sibling)
2 rebind_subsystems(): if (ss->root != &rootnode)
rcu_assign_pointer(ss->root, root);
rcu_assign_pointer(subsys[i]->root, &rootnode);
3 cgroup_has_css_refs(): if (ss->root != cgrp->root)
4 cgroup_init_subsys(): ss->root = &rootnode;
5 proc_cgroupstats_show(): ss->name, ss->root->subsys_bits,
ss->root->number_of_cgroups, !ss->disabled);
6 cgroup_clone(): root = subsys->root;
if ((root != subsys->root) ||
All these place we have held cgroup_lock() or we don't dereference to
struct cgroupfs_root. It's means wo don't need RCU when use struct
cgroup_subsys.root, and we should not put struct cgroupfs_root protected
by RCU.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We access res->cgroups without the task_lock(), so res->cgroups may be
changed. it's unreliable, and "if (l == &res->cgroups->tasks)" may be
false forever.
We don't need add any lock for fixing this bug. we just access to struct
css_set by struct cg_cgroup_link, not by struct task_struct.
Since we hold css_set_lock, struct cg_cgroup_link is reliable.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- In cgroup_clone(), if vfs_mkdir() returns successfully,
dentry->d_fsdata will be the pointer to the newly created
cgroup and won't be NULL.
- a cgroup file's dentry->d_fsdata won't be NULL, guaranteed
by cgroup_add_file().
- When walking through the subsystems of a cgroup_fs (using
for_each_subsys), cgrp->subsys[ss->subsys_id] won't be NULL,
guaranteed by cgroup_create().
(Also remove 2 unused variables in cgroup_rmdir().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix commit_creds()'s handling of a process that has no mm (such as one that is
calling or has called daemonize()). commit_creds() should check to see if
task->mm is not NULL before calling set_dumpable() on it.
Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
NOMMU mmap allocates a piece of memory for an mmap that's rounded up in size to
the nearest power-of-2 number of pages. Currently it then discards the excess
pages back to the page allocator, making that memory available for use by other
things. This can, however, cause greater amount of fragmentation.
To counter this, a sysctl is added in order to fine-tune the trimming
behaviour. The default behaviour remains to trim pages aggressively, while
this can either be disabled completely or set to a higher page-granular
watermark in order to have finer-grained control.
vm region vm_top bits taken from an earlier patch by David Howells.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Mike Frysinger <vapier.adi@gmail.com>
