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Since the tasklist is protected by rcu list operations, it is safe
to convert the read_lock()s to rcu_read_lock().
Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: extend the scope of hung-task checks
Changed the default value of hung_task_check_count to PID_MAX_LIMIT.
hung_task_batch_count added to put an upper bound on the critical
section. Every hung_task_batch_count checks, the rcu lock is never
held for a too long time.
Keeping the critical section small minimizes time preemption is disabled
and keeps rcu grace periods small.
To prevent following a stale pointer, get_task_struct is called on g and t.
To verify that g and t have not been unhashed while outside the critical
section, the task states are checked.
The design was proposed by Frédéric Weisbecker.
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Suggested-by: Frédéric Weisbecker <fweisbec@gmail.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: fix potential false panic
A potential race exists if sysctl_hung_task_timeout_secs is reset to 0
while inside check_hung_uniterruptible_tasks(). If check_task() is
entered, a comparison with 0 will result in a false hung_task being
detected.
If sysctl_hung_task_panic is set, the system will panic.
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Fixes the following compile error:
kernel/fork.c:1049: error: 'struct task_struct' has no member named 'last_switch_count'
kernel/fork.c:1050: error: 'struct task_struct' has no member named 'last_switch_timestamp'
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Decoupling allows:
* hung tasks check to happen at very low priority
* hung tasks check and softlockup to be enabled/disabled independently
at compile and/or run-time
* individual panic settings to be enabled disabled independently
at compile and/or run-time
* softlockup threshold to be reduced without increasing hung tasks
poll frequency (hung task check is expensive relative to softlock watchdog)
* hung task check to be zero over-head when disabled at run-time
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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At run-time, if softlockup_thresh is changed to a much lower value,
touch_timestamp is likely to be much older than the new softlock_thresh.
This will cause a false softlockup to be detected. If softlockup_panic
is enabled, the system will panic.
The fix is to touch all watchdogs before changing softlockup_thresh.
Signed-off-by: Mandeep Singh Baines <msb@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: reduce memory footprint
add __cpuinit to rcu_init_percpu_data(), and this function's text
will be discarded after boot when !CONFIG_HOTPLUG_CPU.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
smp_call_function_single(): be slightly less stupid, fix #2
lockdep, mm: fix might_fault() annotation
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At 37000 feet somewhere near Greenland I woke up from a half-sleep with the
realisation that __lowest_in_progress() is buggy. After landing I checked
and there were indeed 2 problems with it; this patch fixes both:
* The order of the list checks was wrong
* The locking was not correct.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
kernel/sched.c: add missing forward declaration for 'double_rq_lock'
sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()"
cpumask: fix CONFIG_NUMA=y sched.c
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fix m68k build failure:
tip/kernel/up.c: In function 'smp_call_function_single':
tip/kernel/up.c:16: error: dereferencing pointer to incomplete type
make[2]: *** [kernel/up.o] Error 1
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: build fix on certain configs
Added 'double_rq_lock' forward declaration, allowing double_rq_lock
to be used in _double_lock_balance().
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: build fix on Alpha
kernel/up.c: In function 'smp_call_function_single':
kernel/up.c:12: error: 'cpuid' undeclared (first use in this function)
kernel/up.c:12: error: (Each undeclared identifier is reported only once
kernel/up.c:12: error: for each function it appears in.)
The typo didnt show up on x86 because 'cpuid' happens to be a
function address as well ...
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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If you do
smp_call_function_single(expression-with-side-effects, ...)
then expression-with-side-effects never gets evaluated on UP builds.
As always, implementing it in C is the correct thing to do.
While we're there, uninline it for size and possible header dependency
reasons.
And create a new kernel/up.c, as a place in which to put
uniprocessor-specific code and storage. It should mirror kernel/smp.c.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: avoid accessing NULL tg.css->cgroup
In commit 0a0db8f5c9d4bbb9bbfcc2b6cb6bce2d0ef4d73d, I removed checking
NULL tg.css->cgroup, but I realized I was wrong when I found reading
/proc/sched_debug can race with cgroup_create().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: fix panic on ia64 with NR_CPUS=1024
struct sched_domain is now a dangling structure; where we really want
static ones, we need to use static_sched_domain.
(As the FIXME in this file says, cpumask_var_t would be better, but
this code is hairy enough without trying to add initialization code to
the right places).
Reported-by: Mike Travis <travis@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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* 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
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* 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()
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git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
CRED: Fix commit_creds() on a process that has no mm
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... and have it default off.
This does allow people to work with it for testing.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile
* '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
...
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* '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
...
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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>
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Missing put_cred() in the error handling path of prepare_kernel_cred().
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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>
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Use the new generic implementation.
Signed-off-by: Wu Fengguang <wfg@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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>
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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>
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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>
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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>
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Impact: reduce stack usage
Allocate a global cpumask_var_t at boot, and use it in cpuset_attach(), so
we won't fail cpuset_attach().
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>
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Impact: reduce stack usage
Just use cs->cpus_allowed, and no need to allocate a cpumask_var_t.
Signed-off-by: Li Zefan <lizf@cn.fujistu.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>
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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>
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top cpuset
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>
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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>
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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>
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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>
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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>
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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>
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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>
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Add a common function link_css_set() to link a css_set to a cgroup.
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>
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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>
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Don't link rootnode to the root list, so root_list contains active
hierarchies only as the comment indicates. And rename for_each_root() to
for_each_active_root().
Also remove redundant check in cgroup_kill_sb().
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>
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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>
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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>
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Use task_lock() protect tsk->cgroups and get_css_set(tsk->cgroups).
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>
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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>
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