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The membarrier_state field is located within the mm_struct, which
is not guaranteed to exist when used from runqueue-lock-free iteration
on runqueues by the membarrier system call.
Copy the membarrier_state from the mm_struct into the scheduler runqueue
when the scheduler switches between mm.
When registering membarrier for mm, after setting the registration bit
in the mm membarrier state, issue a synchronize_rcu() to ensure the
scheduler observes the change. In order to take care of the case
where a runqueue keeps executing the target mm without swapping to
other mm, iterate over each runqueue and issue an IPI to copy the
membarrier_state from the mm_struct into each runqueue which have the
same mm which state has just been modified.
Move the mm membarrier_state field closer to pgd in mm_struct to use
a cache line already touched by the scheduler switch_mm.
The membarrier_execve() (now membarrier_exec_mmap) hook now needs to
clear the runqueue's membarrier state in addition to clear the mm
membarrier state, so move its implementation into the scheduler
membarrier code so it can access the runqueue structure.
Add memory barrier in membarrier_exec_mmap() prior to clearing
the membarrier state, ensuring memory accesses executed prior to exec
are not reordered with the stores clearing the membarrier state.
As suggested by Linus, move all membarrier.c RCU read-side locks outside
of the for each cpu loops.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-5-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Checking that the number of threads is 1 is redundant with checking
mm_users == 1.
No change in functionality intended.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Fix a logic flaw in the way membarrier_register_private_expedited()
handles ready state checks for private expedited sync core and private
expedited registrations.
If a private expedited membarrier registration is first performed, and
then a private expedited sync_core registration is performed, the ready
state check will skip the second registration when it really should not.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-2-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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The current task on the runqueue is currently read with rcu_dereference().
To obtain ordinary RCU semantics for an rcu_dereference() of rq->curr it needs
to be paired with rcu_assign_pointer() of rq->curr. Which provides the
memory barrier necessary to order assignments to the task_struct
and the assignment to rq->curr.
Unfortunately the assignment of rq->curr in __schedule is a hot path,
and it has already been show that additional barriers in that code
will reduce the performance of the scheduler. So I will attempt to
describe below why you can effectively have ordinary RCU semantics
without any additional barriers.
The assignment of rq->curr in init_idle is a slow path called once
per cpu and that can use rcu_assign_pointer() without any concerns.
As I write this there are effectively two users of rcu_dereference() on
rq->curr. There is the membarrier code in kernel/sched/membarrier.c
that only looks at "->mm" after the rcu_dereference(). Then there is
task_numa_compare() in kernel/sched/fair.c. My best reading of the
code shows that task_numa_compare only access: "->flags",
"->cpus_ptr", "->numa_group", "->numa_faults[]",
"->total_numa_faults", and "->se.cfs_rq".
The code in __schedule() essentially does:
rq_lock(...);
smp_mb__after_spinlock();
next = pick_next_task(...);
rq->curr = next;
context_switch(prev, next);
At the start of the function the rq_lock/smp_mb__after_spinlock
pair provides a full memory barrier. Further there is a full memory barrier
in context_switch().
This means that any task that has already run and modified itself (the
common case) has already seen two memory barriers before __schedule()
runs and begins executing. A task that modifies itself then sees a
third full memory barrier pair with the rq_lock();
For a brand new task that is enqueued with wake_up_new_task() there
are the memory barriers present from the taking and release the
pi_lock and the rq_lock as the processes is enqueued as well as the
full memory barrier at the start of __schedule() assuming __schedule()
happens on the same cpu.
This means that by the time we reach the assignment of rq->curr
except for values on the task struct modified in pick_next_task
the code has the same guarantees as if it used rcu_assign_pointer().
Reading through all of the implementations of pick_next_task it
appears pick_next_task is limited to modifying the task_struct fields
"->se", "->rt", "->dl". These fields are the sched_entity structures
of the varies schedulers.
Further "->se.cfs_rq" is only changed in cgroup attach/move operations
initialized by userspace.
Unless I have missed something this means that in practice that the
users of "rcu_dereference(rq->curr)" get normal RCU semantics of
rcu_dereference() for the fields the care about, despite the
assignment of rq->curr in __schedule() ot using rcu_assign_pointer.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20190903200603.GW2349@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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unnecessary code
Remove work arounds that were written before there was a grace period
after tasks left the runqueue in finish_task_switch().
In particular now that there tasks exiting the runqueue exprience
a RCU grace period none of the work performed by task_rcu_dereference()
excpet the rcu_dereference() is necessary so replace task_rcu_dereference()
with rcu_dereference().
Remove the code in rcuwait_wait_event() that checks to ensure the current
task has not exited. It is no longer necessary as it is guaranteed
that any running task will experience a RCU grace period after it
leaves the run queueue.
Remove the comment in rcuwait_wake_up() as it is no longer relevant.
Ref: 8f95c90ceb54 ("sched/wait, RCU: Introduce rcuwait machinery")
Ref: 150593bf8693 ("sched/api: Introduce task_rcu_dereference() and try_get_task_struct()")
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87lfurdpk9.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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leaving the runqueue
In the ordinary case today the RCU grace period for a task_struct is
triggered when another process wait's for it's zombine and causes the
kernel to call release_task(). As the waiting task has to receive a
signal and then act upon it before this happens, typically this will
occur after the original task as been removed from the runqueue.
Unfortunaty in some cases such as self reaping tasks it can be shown
that release_task() will be called starting the grace period for
task_struct long before the task leaves the runqueue.
Therefore use put_task_struct_rcu_user() in finish_task_switch() to
guarantee that the there is a RCU lifetime after the task
leaves the runqueue.
Besides the change in the start of the RCU grace period for the
task_struct this change may cause perf_event_delayed_put and
trace_sched_process_free. The function perf_event_delayed_put boils
down to just a WARN_ON for cases that I assume never show happen. So
I don't see any problem with delaying it.
The function trace_sched_process_free is a trace point and thus
visible to user space. Occassionally userspace has the strangest
dependencies so this has a miniscule chance of causing a regression.
This change only changes the timing of when the tracepoint is called.
The change in timing arguably gives userspace a more accurate picture
of what is going on. So I don't expect there to be a regression.
In the case where a task self reaps we are pretty much guaranteed that
the RCU grace period is delayed. So we should get quite a bit of
coverage in of this worst case for the change in a normal threaded
workload. So I expect any issues to turn up quickly or not at all.
I have lightly tested this change and everything appears to work
fine.
Inspired-by: Linus Torvalds <torvalds@linux-foundation.org>
Inspired-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87r24jdpl5.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Add a count of the number of RCU users (currently 1) of the task
struct so that we can later add the scheduler case and get rid of the
very subtle task_rcu_dereference(), and just use rcu_dereference().
As suggested by Oleg have the count overlap rcu_head so that no
additional space in task_struct is required.
Inspired-by: Linus Torvalds <torvalds@linux-foundation.org>
Inspired-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/87woebdplt.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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cfs_rq_clock_task() was first introduced and used in:
f1b17280efbd ("sched: Maintain runnable averages across throttled periods")
Over time its use has been graduately removed by the following commits:
d31b1a66cbe0 ("sched/fair: Factorize PELT update")
23127296889f ("sched/fair: Update scale invariance of PELT")
Today, there is no single user left, so it can be safely removed.
Found via the -Wunused-function build warning.
Signed-off-by: Qian Cai <cai@lca.pw>
Cc: Ben Segall <bsegall@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/1568668775-2127-1-git-send-email-cai@lca.pw
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu-feature updates from Ingo Molnar:
- Rework the Intel model names symbols/macros, which were decades of
ad-hoc extensions and added random noise. It's now a coherent, easy
to follow nomenclature.
- Add new Intel CPU model IDs:
- "Tiger Lake" desktop and mobile models
- "Elkhart Lake" model ID
- and the "Lightning Mountain" variant of Airmont, plus support code
- Add the new AVX512_VP2INTERSECT instruction to cpufeatures
- Remove Intel MPX user-visible APIs and the self-tests, because the
toolchain (gcc) is not supporting it going forward. This is the
first, lowest-risk phase of MPX removal.
- Remove X86_FEATURE_MFENCE_RDTSC
- Various smaller cleanups and fixes
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
x86/cpu: Update init data for new Airmont CPU model
x86/cpu: Add new Airmont variant to Intel family
x86/cpu: Add Elkhart Lake to Intel family
x86/cpu: Add Tiger Lake to Intel family
x86: Correct misc typos
x86/intel: Add common OPTDIFFs
x86/intel: Aggregate microserver naming
x86/intel: Aggregate big core graphics naming
x86/intel: Aggregate big core mobile naming
x86/intel: Aggregate big core client naming
x86/cpufeature: Explain the macro duplication
x86/ftrace: Remove mcount() declaration
x86/PCI: Remove superfluous returns from void functions
x86/msr-index: Move AMD MSRs where they belong
x86/cpu: Use constant definitions for CPU models
lib: Remove redundant ftrace flag removal
x86/crash: Remove unnecessary comparison
x86/bitops: Use __builtin_constant_p() directly instead of IS_IMMEDIATE()
x86: Remove X86_FEATURE_MFENCE_RDTSC
x86/mpx: Remove MPX APIs
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and
Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann,
Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers.
As perf and the scheduler is getting bigger and more complex,
document the status quo of current responsibilities and interests,
and spread the review pain^H^H^H^H fun via an increase in the Cc:
linecount generated by scripts/get_maintainer.pl. :-)
- Add another series of patches that brings the -rt (PREEMPT_RT) tree
closer to mainline: split the monolithic CONFIG_PREEMPT dependencies
into a new CONFIG_PREEMPTION category that will allow the eventual
introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches
to go though.
- Extend the CPU cgroup controller with uclamp.min and uclamp.max to
allow the finer shaping of CPU bandwidth usage.
- Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS).
- Improve the behavior of high CPU count, high thread count
applications running under cpu.cfs_quota_us constraints.
- Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present.
- Improve CPU isolation housekeeping CPU allocation NUMA locality.
- Fix deadline scheduler bandwidth calculations and logic when cpusets
rebuilds the topology, or when it gets deadline-throttled while it's
being offlined.
- Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from
setscheduler() system calls without creating global serialization.
Add new synchronization between cpuset topology-changing events and
the deadline acceptance tests in setscheduler(), which were broken
before.
- Rework the active_mm state machine to be less confusing and more
optimal.
- Rework (simplify) the pick_next_task() slowpath.
- Improve load-balancing on AMD EPYC systems.
- ... and misc cleanups, smaller fixes and improvements - please see
the Git log for more details.
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
sched/psi: Correct overly pessimistic size calculation
sched/fair: Speed-up energy-aware wake-ups
sched/uclamp: Always use 'enum uclamp_id' for clamp_id values
sched/uclamp: Update CPU's refcount on TG's clamp changes
sched/uclamp: Use TG's clamps to restrict TASK's clamps
sched/uclamp: Propagate system defaults to the root group
sched/uclamp: Propagate parent clamps
sched/uclamp: Extend CPU's cgroup controller
sched/topology: Improve load balancing on AMD EPYC systems
arch, ia64: Make NUMA select SMP
sched, perf: MAINTAINERS update, add submaintainers and reviewers
sched/fair: Use rq_lock/unlock in online_fair_sched_group
cpufreq: schedutil: fix equation in comment
sched: Rework pick_next_task() slow-path
sched: Allow put_prev_task() to drop rq->lock
sched/fair: Expose newidle_balance()
sched: Add task_struct pointer to sched_class::set_curr_task
sched: Rework CPU hotplug task selection
sched/{rt,deadline}: Fix set_next_task vs pick_next_task
sched: Fix kerneldoc comment for ia64_set_curr_task
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
"Kernel side changes:
- Improved kbprobes robustness
- Intel PEBS support for PT hardware tracing
- Other Intel PT improvements: high order pages memory footprint
reduction and various related cleanups
- Misc cleanups
The perf tooling side has been very busy in this cycle, with over 300
commits. This is an incomplete high-level summary of the many
improvements done by over 30 developers:
- Lots of updates to the following tools:
'perf c2c'
'perf config'
'perf record'
'perf report'
'perf script'
'perf test'
'perf top'
'perf trace'
- Updates to libperf and libtraceevent, and a consolidation of the
proliferation of x86 instruction decoder libraries.
- Vendor event updates for Intel and PowerPC CPUs,
- Updates to hardware tracing tooling for ARM and Intel CPUs,
- ... and lots of other changes and cleanups - see the shortlog and
Git log for details"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (322 commits)
kprobes: Prohibit probing on BUG() and WARN() address
perf/x86: Make more stuff static
x86, perf: Fix the dependency of the x86 insn decoder selftest
objtool: Ignore intentional differences for the x86 insn decoder
objtool: Update sync-check.sh from perf's check-headers.sh
perf build: Ignore intentional differences for the x86 insn decoder
perf intel-pt: Use shared x86 insn decoder
perf intel-pt: Remove inat.c from build dependency list
perf: Update .gitignore file
objtool: Move x86 insn decoder to a common location
perf metricgroup: Support multiple events for metricgroup
perf metricgroup: Scale the metric result
perf pmu: Change convert_scale from static to global
perf symbols: Move mem_info and branch_info out of symbol.h
perf auxtrace: Uninline functions that touch perf_session
perf tools: Remove needless evlist.h include directives
perf tools: Remove needless evlist.h include directives
perf tools: Remove needless thread_map.h include directives
perf tools: Remove needless thread.h include directives
perf tools: Remove needless map.h include directives
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- improve rwsem scalability
- add uninitialized rwsem debugging check
- reduce lockdep's stacktrace memory usage and add diagnostics
- misc cleanups, code consolidation and constification
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mutex: Fix up mutex_waiter usage
locking/mutex: Use mutex flags macro instead of hard code
locking/mutex: Make __mutex_owner static to mutex.c
locking/qspinlock,x86: Clarify virt_spin_lock_key
locking/rwsem: Check for operations on an uninitialized rwsem
locking/rwsem: Make handoff writer optimistically spin on owner
locking/lockdep: Report more stack trace statistics
locking/lockdep: Reduce space occupied by stack traces
stacktrace: Constify 'entries' arguments
locking/lockdep: Make it clear that what lock_class::key points at is not modified
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar:
"This cycle's RCU changes were:
- A few more RCU flavor consolidation cleanups.
- Updates to RCU's list-traversal macros improving lockdep usability.
- Forward-progress improvements for no-CBs CPUs: Avoid ignoring
incoming callbacks during grace-period waits.
- Forward-progress improvements for no-CBs CPUs: Use ->cblist
structure to take advantage of others' grace periods.
- Also added a small commit that avoids needlessly inflicting
scheduler-clock ticks on callback-offloaded CPUs.
- Forward-progress improvements for no-CBs CPUs: Reduce contention on
->nocb_lock guarding ->cblist.
- Forward-progress improvements for no-CBs CPUs: Add ->nocb_bypass
list to further reduce contention on ->nocb_lock guarding ->cblist.
- Miscellaneous fixes.
- Torture-test updates.
- minor LKMM updates"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits)
MAINTAINERS: Update from paulmck@linux.ibm.com to paulmck@kernel.org
rcu: Don't include <linux/ktime.h> in rcutiny.h
rcu: Allow rcu_do_batch() to dynamically adjust batch sizes
rcu/nocb: Don't wake no-CBs GP kthread if timer posted under overload
rcu/nocb: Reduce __call_rcu_nocb_wake() leaf rcu_node ->lock contention
rcu/nocb: Reduce nocb_cb_wait() leaf rcu_node ->lock contention
rcu/nocb: Advance CBs after merge in rcutree_migrate_callbacks()
rcu/nocb: Avoid synchronous wakeup in __call_rcu_nocb_wake()
rcu/nocb: Print no-CBs diagnostics when rcutorture writer unduly delayed
rcu/nocb: EXP Check use and usefulness of ->nocb_lock_contended
rcu/nocb: Add bypass callback queueing
rcu/nocb: Atomic ->len field in rcu_segcblist structure
rcu/nocb: Unconditionally advance and wake for excessive CBs
rcu/nocb: Reduce ->nocb_lock contention with separate ->nocb_gp_lock
rcu/nocb: Reduce contention at no-CBs invocation-done time
rcu/nocb: Reduce contention at no-CBs registry-time CB advancement
rcu/nocb: Round down for number of no-CBs grace-period kthreads
rcu/nocb: Avoid ->nocb_lock capture by corresponding CPU
rcu/nocb: Avoid needless wakeups of no-CBs grace-period kthread
rcu/nocb: Make __call_rcu_nocb_wake() safe for many callbacks
...
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
Pull parisc updates from Helge Deller:
- Make the powerpc implementation to read elf files available as a
public kexec interface so it can be re-used on other architectures
(Sven)
- Implement kexec on parisc (Sven)
- Add kprobes on ftrace on parisc (Sven)
- Fix kernel crash with HSC-PCI cards based on card-mode Dino
- Add assembly implementations for memset, strlen, strcpy, strncpy and
strcat
- Some cleanups, documentation updates, warning fixes, ...
* 'parisc-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: (25 commits)
parisc: Have git ignore generated real2.S and firmware.c
parisc: Disable HP HSC-PCI Cards to prevent kernel crash
parisc: add support for kexec_file_load() syscall
parisc: wire up kexec_file_load syscall
parisc: add kexec syscall support
parisc: add __pdc_cpu_rendezvous()
kprobes/parisc: remove arch_kprobe_on_func_entry()
kexec_elf: support 32 bit ELF files
kexec_elf: remove unused variable in kexec_elf_load()
kexec_elf: remove Elf_Rel macro
kexec_elf: remove PURGATORY_STACK_SIZE
kexec_elf: remove parsing of section headers
kexec_elf: change order of elf_*_to_cpu() functions
kexec: add KEXEC_ELF
parisc: Save some bytes in dino driver
parisc: Drop comments which are already in pci.h
parisc: Convert eisa_enumerator to use pr_cont()
parisc: Avoid warning when loading hppb driver
parisc: speed up flush_tlb_all_local with qemu
parisc: Add ALTERNATIVE_CODE() and ALT_COND_RUN_ON_QEMU
...
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux
Pull ia64 updates from Tony Luck:
"The big change here is removal of support for SGI Altix"
* tag 'please-pull-ia64_for_5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux: (33 commits)
genirq: remove the is_affinity_mask_valid hook
ia64: remove CONFIG_SWIOTLB ifdefs
ia64: remove support for machvecs
ia64: move the screen_info setup to common code
ia64: move the ROOT_DEV setup to common code
ia64: rework iommu probing
ia64: remove the unused sn_coherency_id symbol
ia64: remove the SGI UV simulator support
ia64: remove the zx1 swiotlb machvec
ia64: remove CONFIG_ACPI ifdefs
ia64: remove CONFIG_PCI ifdefs
ia64: remove the hpsim platform
ia64: remove now unused machvec indirections
ia64: remove support for the SGI SN2 platform
drivers: remove the SGI SN2 IOC4 base support
drivers: remove the SGI SN2 IOC3 base support
qla2xxx: remove SGI SN2 support
qla1280: remove SGI SN2 support
misc/sgi-xp: remove SGI SN2 support
char/mspec: remove SGI SN2 support
...
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
"Although there isn't tonnes of code in terms of line count, there are
a fair few headline features which I've noted both in the tag and also
in the merge commits when I pulled everything together.
The part I'm most pleased with is that we had 35 contributors this
time around, which feels like a big jump from the usual small group of
core arm64 arch developers. Hopefully they all enjoyed it so much that
they'll continue to contribute, but we'll see.
It's probably worth highlighting that we've pulled in a branch from
the risc-v folks which moves our CPU topology code out to where it can
be shared with others.
Summary:
- 52-bit virtual addressing in the kernel
- New ABI to allow tagged user pointers to be dereferenced by
syscalls
- Early RNG seeding by the bootloader
- Improve robustness of SMP boot
- Fix TLB invalidation in light of recent architectural
clarifications
- Support for i.MX8 DDR PMU
- Remove direct LSE instruction patching in favour of static keys
- Function error injection using kprobes
- Support for the PPTT "thread" flag introduced by ACPI 6.3
- Move PSCI idle code into proper cpuidle driver
- Relaxation of implicit I/O memory barriers
- Build with RELR relocations when toolchain supports them
- Numerous cleanups and non-critical fixes"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (114 commits)
arm64: remove __iounmap
arm64: atomics: Use K constraint when toolchain appears to support it
arm64: atomics: Undefine internal macros after use
arm64: lse: Make ARM64_LSE_ATOMICS depend on JUMP_LABEL
arm64: asm: Kill 'asm/atomic_arch.h'
arm64: lse: Remove unused 'alt_lse' assembly macro
arm64: atomics: Remove atomic_ll_sc compilation unit
arm64: avoid using hard-coded registers for LSE atomics
arm64: atomics: avoid out-of-line ll/sc atomics
arm64: Use correct ll/sc atomic constraints
jump_label: Don't warn on __exit jump entries
docs/perf: Add documentation for the i.MX8 DDR PMU
perf/imx_ddr: Add support for AXI ID filtering
arm64: kpti: ensure patched kernel text is fetched from PoU
arm64: fix fixmap copy for 16K pages and 48-bit VA
perf/smmuv3: Validate groups for global filtering
perf/smmuv3: Validate group size
arm64: Relax Documentation/arm64/tagged-pointers.rst
arm64: kvm: Replace hardcoded '1' with SYS_PAR_EL1_F
arm64: mm: Ignore spurious translation faults taken from the kernel
...
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|
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu
Pull iommu updates from Joerg Roedel:
- batched unmap support for the IOMMU-API
- support for unlocked command queueing in the ARM-SMMU driver
- rework the ATS support in the ARM-SMMU driver
- more refactoring in the ARM-SMMU driver to support hardware
implemention specific quirks and errata
- bounce buffering DMA-API implementatation in the Intel VT-d driver
for untrusted devices (like Thunderbolt devices)
- fixes for runtime PM support in the OMAP iommu driver
- MT8183 IOMMU support in the Mediatek IOMMU driver
- rework of the way the IOMMU core sets the default domain type for
groups. Changing the default domain type on x86 does not require two
kernel parameters anymore.
- more smaller fixes and cleanups
* tag 'iommu-updates-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (113 commits)
iommu/vt-d: Declare Broadwell igfx dmar support snafu
iommu/vt-d: Add Scalable Mode fault information
iommu/vt-d: Use bounce buffer for untrusted devices
iommu/vt-d: Add trace events for device dma map/unmap
iommu/vt-d: Don't switch off swiotlb if bounce page is used
iommu/vt-d: Check whether device requires bounce buffer
swiotlb: Split size parameter to map/unmap APIs
iommu/omap: Mark pm functions __maybe_unused
iommu/ipmmu-vmsa: Disable cache snoop transactions on R-Car Gen3
iommu/ipmmu-vmsa: Move IMTTBCR_SL0_TWOBIT_* to restore sort order
iommu: Don't use sme_active() in generic code
iommu/arm-smmu-v3: Fix build error without CONFIG_PCI_ATS
iommu/qcom: Use struct_size() helper
iommu: Remove wrong default domain comments
iommu/dma: Fix for dereferencing before null checking
iommu/mediatek: Clean up struct mtk_smi_iommu
memory: mtk-smi: Get rid of need_larbid
iommu/mediatek: Fix VLD_PA_RNG register backup when suspend
memory: mtk-smi: Add bus_sel for mt8183
memory: mtk-smi: Invoke pm runtime_callback to enable clocks
...
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|
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull pidfd/waitid updates from Christian Brauner:
"This contains two features and various tests.
First, it adds support for waiting on process through pidfds by adding
the P_PIDFD type to the waitid() syscall. This completes the basic
functionality of the pidfd api (cf. [1]). In the meantime we also have
a new adition to the userspace projects that make use of the pidfd
api. The qt project was nice enough to send a mail pointing out that
they have a pr up to switch to the pidfd api (cf. [2]).
Second, this tag contains an extension to the waitid() syscall to make
it possible to wait on the current process group in a race free manner
(even though the actual problem is very unlikely) by specifing 0
together with the P_PGID type. This extension traces back to a
discussion on the glibc development mailing list.
There are also a range of tests for the features above. Additionally,
the test-suite which detected the pidfd-polling race we fixed in [3]
is included in this tag"
[1] https://lwn.net/Articles/794707/
[2] https://codereview.qt-project.org/c/qt/qtbase/+/108456
[3] commit b191d6491be6 ("pidfd: fix a poll race when setting exit_state")
* tag 'core-process-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
waitid: Add support for waiting for the current process group
tests: add pidfd poll tests
tests: move common definitions and functions into pidfd.h
pidfd: add pidfd_wait tests
pidfd: add P_PIDFD to waitid()
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Pick up the first couple of patches working towards PREEMPT_RT.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
Pull networking fixes from David Miller:
1) Don't corrupt xfrm_interface parms before validation, from Nicolas
Dichtel.
2) Revert use of usb-wakeup in btusb, from Mario Limonciello.
3) Block ipv6 packets in bridge netfilter if ipv6 is disabled, from
Leonardo Bras.
4) IPS_OFFLOAD not honored in ctnetlink, from Pablo Neira Ayuso.
5) Missing ULP check in sock_map, from John Fastabend.
6) Fix receive statistic handling in forcedeth, from Zhu Yanjun.
7) Fix length of SKB allocated in 6pack driver, from Christophe
JAILLET.
8) ip6_route_info_create() returns an error pointer, not NULL. From
Maciej Żenczykowski.
9) Only add RDS sock to the hashes after rs_transport is set, from
Ka-Cheong Poon.
10) Don't double clean TX descriptors in ixgbe, from Ilya Maximets.
11) Presence of transmit IPSEC offload in an SKB is not tested for
correctly in ixgbe and ixgbevf. From Steffen Klassert and Jeff
Kirsher.
12) Need rcu_barrier() when register_netdevice() takes one of the
notifier based failure paths, from Subash Abhinov Kasiviswanathan.
13) Fix leak in sctp_do_bind(), from Mao Wenan.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (72 commits)
cdc_ether: fix rndis support for Mediatek based smartphones
sctp: destroy bucket if failed to bind addr
sctp: remove redundant assignment when call sctp_get_port_local
sctp: change return type of sctp_get_port_local
ixgbevf: Fix secpath usage for IPsec Tx offload
sctp: Fix the link time qualifier of 'sctp_ctrlsock_exit()'
ixgbe: Fix secpath usage for IPsec TX offload.
net: qrtr: fix memort leak in qrtr_tun_write_iter
net: Fix null de-reference of device refcount
ipv6: Fix the link time qualifier of 'ping_v6_proc_exit_net()'
tun: fix use-after-free when register netdev failed
tcp: fix tcp_ecn_withdraw_cwr() to clear TCP_ECN_QUEUE_CWR
ixgbe: fix double clean of Tx descriptors with xdp
ixgbe: Prevent u8 wrapping of ITR value to something less than 10us
mlx4: fix spelling mistake "veify" -> "verify"
net: hns3: fix spelling mistake "undeflow" -> "underflow"
net: lmc: fix spelling mistake "runnin" -> "running"
NFC: st95hf: fix spelling mistake "receieve" -> "receive"
net/rds: An rds_sock is added too early to the hash table
mac80211: Do not send Layer 2 Update frame before authorization
...
|
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When passing a equal or more then 32 bytes long string to psi_write(),
psi_write() copies 31 bytes to its buf and overwrites buf[30]
with '\0'. Which makes the input string 1 byte shorter than
it should be.
Fix it by copying sizeof(buf) bytes when nbytes >= sizeof(buf).
This does not cause problems in normal use case like:
"some 500000 10000000" or "full 500000 10000000" because they
are less than 32 bytes in length.
/* assuming nbytes == 35 */
char buf[32];
buf_size = min(nbytes, (sizeof(buf) - 1)); /* buf_size = 31 */
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
buf[buf_size - 1] = '\0'; /* buf[30] = '\0' */
Before:
%cd /proc/pressure/
%echo "123456789|123456789|123456789|1234" > memory
[ 22.473497] nbytes=35,buf_size=31
[ 22.473775] 123456789|123456789|123456789| (print 30 chars)
%sh: write error: Invalid argument
%echo "123456789|123456789|123456789|1" > memory
[ 64.916162] nbytes=32,buf_size=31
[ 64.916331] 123456789|123456789|123456789| (print 30 chars)
%sh: write error: Invalid argument
After:
%cd /proc/pressure/
%echo "123456789|123456789|123456789|1234" > memory
[ 254.837863] nbytes=35,buf_size=32
[ 254.838541] 123456789|123456789|123456789|1 (print 31 chars)
%sh: write error: Invalid argument
%echo "123456789|123456789|123456789|1" > memory
[ 9965.714935] nbytes=32,buf_size=32
[ 9965.715096] 123456789|123456789|123456789|1 (print 31 chars)
%sh: write error: Invalid argument
Also remove the superfluous parentheses.
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Cc: <linux-mediatek@lists.infradead.org>
Cc: <wsd_upstream@mediatek.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190912103452.13281-1-miles.chen@mediatek.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
EAS computes the energy impact of migrating a waking task when deciding
on which CPU it should run. However, the current approach is known to
have a high algorithmic complexity, which can result in prohibitively
high wake-up latencies on systems with complex energy models, such as
systems with per-CPU DVFS. On such systems, the algorithm complexity is
in O(n^2) (ignoring the cost of searching for performance states in the
EM) with 'n' the number of CPUs.
To address this, re-factor the EAS wake-up path to compute the energy
'delta' (with and without the task) on a per-performance domain basis,
rather than system-wide, which brings the complexity down to O(n).
No functional changes intended.
Test results
~~~~~~~~~~~~
* Setup: Tested on a Google Pixel 3, with a Snapdragon 845 (4+4 CPUs,
A55/A75). Base kernel is 5.3-rc5 + Pixel3 specific patches. Android
userspace, no graphics.
* Test case: Run a periodic rt-app task, with 16ms period, ramping down
from 70% to 10%, in 5% steps of 500 ms each (json avail. at [1]).
Frequencies of all CPUs are pinned to max (using scaling_min_freq
CPUFreq sysfs entries) to reduce variability. The time to run
select_task_rq_fair() is measured using the function profiler
(/sys/kernel/debug/tracing/trace_stat/function*). See the test script
for more details [2].
Test 1:
I hacked the DT to 'fake' per-CPU DVFS. That is, we end up with one
CPUFreq policy per CPU (8 policies in total). Since all frequencies are
pinned to max for the test, this should have no impact on the actual
frequency selection, but it does in the EAS calculation.
+---------------------------+----------------------------------+
| Without patch | With patch |
+-----+-----+----------+----------+-----+-----------------+----------+
| CPU | Hit | Avg (us) | s^2 (us) | Hit | Avg (us) | s^2 (us) |
|-----+-----+----------+----------+-----+-----------------+----------+
| 0 | 274 | 38.303 | 1750.239 | 401 | 14.126 (-63.1%) | 146.625 |
| 1 | 197 | 49.529 | 1695.852 | 314 | 16.135 (-67.4%) | 167.525 |
| 2 | 142 | 34.296 | 1758.665 | 302 | 14.133 (-58.8%) | 130.071 |
| 3 | 172 | 31.734 | 1490.975 | 641 | 14.637 (-53.9%) | 139.189 |
| 4 | 316 | 7.834 | 178.217 | 425 | 5.413 (-30.9%) | 20.803 |
| 5 | 447 | 8.424 | 144.638 | 556 | 5.929 (-29.6%) | 27.301 |
| 6 | 581 | 14.886 | 346.793 | 456 | 5.711 (-61.6%) | 23.124 |
| 7 | 456 | 10.005 | 211.187 | 997 | 4.708 (-52.9%) | 21.144 |
+-----+-----+----------+----------+-----+-----------------+----------+
* Hit, Avg and s^2 are as reported by the function profiler
Test 2:
I also ran the same test with a normal DT, with 2 CPUFreq policies, to
see if this causes regressions in the most common case.
+---------------------------+----------------------------------+
| Without patch | With patch |
+-----+-----+----------+----------+-----+-----------------+----------+
| CPU | Hit | Avg (us) | s^2 (us) | Hit | Avg (us) | s^2 (us) |
|-----+-----+----------+----------+-----+-----------------+----------+
| 0 | 345 | 22.184 | 215.321 | 580 | 18.635 (-16.0%) | 146.892 |
| 1 | 358 | 18.597 | 200.596 | 438 | 12.934 (-30.5%) | 104.604 |
| 2 | 359 | 25.566 | 200.217 | 397 | 10.826 (-57.7%) | 74.021 |
| 3 | 362 | 16.881 | 200.291 | 718 | 11.455 (-32.1%) | 102.280 |
| 4 | 457 | 3.822 | 9.895 | 757 | 4.616 (+20.8%) | 13.369 |
| 5 | 344 | 4.301 | 7.121 | 594 | 5.320 (+23.7%) | 18.798 |
| 6 | 472 | 4.326 | 7.849 | 464 | 5.648 (+30.6%) | 22.022 |
| 7 | 331 | 4.630 | 13.937 | 408 | 5.299 (+14.4%) | 18.273 |
+-----+-----+----------+----------+-----+-----------------+----------+
* Hit, Avg and s^2 are as reported by the function profiler
In addition to these two tests, I also ran 50 iterations of the Lisa
EAS functional test suite [3] with this patch applied on Arm Juno r0,
Arm Juno r2, Arm TC2 and Hikey960, and could not see any regressions
(all EAS functional tests are passing).
[1] https://paste.debian.net/1100055/
[2] https://paste.debian.net/1100057/
[3] https://github.com/ARM-software/lisa/blob/master/lisa/tests/scheduler/eas_behaviour.py
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Cc: qperret@qperret.net
Cc: rjw@rjwysocki.net
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190912094404.13802-1-qperret@qperret.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
If a new child cgroup is created in the frozen cgroup hierarchy
(one or more of ancestor cgroups is frozen), the CGRP_FREEZE cgroup
flag should be set. Otherwise if a process will be attached to the
child cgroup, it won't become frozen.
The problem can be reproduced with the test_cgfreezer_mkdir test.
This is the output before this patch:
~/test_freezer
ok 1 test_cgfreezer_simple
ok 2 test_cgfreezer_tree
ok 3 test_cgfreezer_forkbomb
Cgroup /sys/fs/cgroup/cg_test_mkdir_A/cg_test_mkdir_B isn't frozen
not ok 4 test_cgfreezer_mkdir
ok 5 test_cgfreezer_rmdir
ok 6 test_cgfreezer_migrate
ok 7 test_cgfreezer_ptrace
ok 8 test_cgfreezer_stopped
ok 9 test_cgfreezer_ptraced
ok 10 test_cgfreezer_vfork
And with this patch:
~/test_freezer
ok 1 test_cgfreezer_simple
ok 2 test_cgfreezer_tree
ok 3 test_cgfreezer_forkbomb
ok 4 test_cgfreezer_mkdir
ok 5 test_cgfreezer_rmdir
ok 6 test_cgfreezer_migrate
ok 7 test_cgfreezer_ptrace
ok 8 test_cgfreezer_stopped
ok 9 test_cgfreezer_ptraced
ok 10 test_cgfreezer_vfork
Reported-by: Mark Crossen <mcrossen@fb.com>
Signed-off-by: Roman Gushchin <guro@fb.com>
Fixes: 76f969e8948d ("cgroup: cgroup v2 freezer")
Cc: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Tejun Heo <tj@kernel.org>
|
|
gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux
Pull clone3 fix from Christian Brauner:
"This is a last-minute bugfix for clone3() that should go in before we
release 5.3 with clone3().
clone3() did not verify that the exit_signal argument was set to a
valid signal. This can be used to cause a crash by specifying a signal
greater than NSIG. e.g. -1.
The commit from Eugene adds a check to copy_clone_args_from_user() to
verify that the exit signal is limited by CSIGNAL as with legacy
clone() and that the signal is valid. With this we don't get the
legacy clone behavior were an invalid signal could be handed down and
would only be detected and then ignored in do_notify_parent(). Users
of clone3() will now get a proper error right when they pass an
invalid exit signal. Note, that this is not a change in user-visible
behavior since no kernel with clone3() has been released yet"
* tag 'for-linus-20190912' of gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux:
fork: block invalid exit signals with clone3()
|
|
Previously, higher 32 bits of exit_signal fields were lost when copied
to the kernel args structure (that uses int as a type for the respective
field). Moreover, as Oleg has noted, exit_signal is used unchecked, so
it has to be checked for sanity before use; for the legacy syscalls,
applying CSIGNAL mask guarantees that it is at least non-negative;
however, there's no such thing is done in clone3() code path, and that
can break at least thread_group_leader.
This commit adds a check to copy_clone_args_from_user() to verify that
the exit signal is limited by CSIGNAL as with legacy clone() and that
the signal is valid. With this we don't get the legacy clone behavior
were an invalid signal could be handed down and would only be detected
and ignored in do_notify_parent(). Users of clone3() will now get a
proper error when they pass an invalid exit signal. Note, that this is
not user-visible behavior since no kernel with clone3() has been
released yet.
The following program will cause a splat on a non-fixed clone3() version
and will fail correctly on a fixed version:
#define _GNU_SOURCE
#include <linux/sched.h>
#include <linux/types.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
pid_t pid = -1;
struct clone_args args = {0};
args.exit_signal = -1;
pid = syscall(__NR_clone3, &args, sizeof(struct clone_args));
if (pid < 0)
exit(EXIT_FAILURE);
if (pid == 0)
exit(EXIT_SUCCESS);
wait(NULL);
exit(EXIT_SUCCESS);
}
Fixes: 7f192e3cd316 ("fork: add clone3")
Reported-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Link: https://lore.kernel.org/r/4b38fa4ce420b119a4c6345f42fe3cec2de9b0b5.1568223594.git.esyr@redhat.com
[christian.brauner@ubuntu.com: simplify check and rework commit message]
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Ingo Molnar:
"Fix an initialization bug in the hw-breakpoints, which triggered on
the ARM platform"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/hw_breakpoint: Fix arch_hw_breakpoint use-before-initialization
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fix from Ingo Molnar:
"Fix a race in the IRQ resend mechanism, which can result in a NULL
dereference crash"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Prevent NULL pointer dereference in resend_irqs()
|
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'arm/qcom', 'arm/renesas', 'x86/amd', 'x86/vt-d' and 'core' into next
|
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This splits the size parameter to swiotlb_tbl_map_single() and
swiotlb_tbl_unmap_single() into an alloc_size and a mapping_size
parameter, where the latter one is rounded up to the iommu page
size.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
|
|
It was recently discovered that the linux version of waitid is not a
superset of the other wait functions because it does not include support
for waiting for the current process group. This has two downsides:
1. An extra system call is needed to get the current process group.
2. After the current process group is received and before it is passed
to waitid a signal could arrive causing the current process group to change.
Inherent race-conditions as these make it impossible for userspace to
emulate this functionaly and thus violate async-signal safety
requirements for waitpid.
Arguments can be made for using a different choice of idtype and id
for this case but the BSDs already use this P_PGID and 0 to indicate
waiting for the current process's process group. So be nice to user
space programmers and don't introduce an unnecessary incompatibility.
Some people have noted that the posix description is that
waitpid will wait for the current process group, and that in
the presence of pthreads that process group can change. To get
clarity on this issue I looked at XNU, FreeBSD, and Luminos. All of
those flavors of unix waited for the current process group at the
time of call and as written could not adapt to the process group
changing after the call.
At one point Linux did adapt to the current process group changing but
that stopped in 161550d74c07 ("pid: sys_wait... fixes"). It has been
over 11 years since Linux has that behavior, no programs that fail
with the change in behavior have been reported, and I could not
find any other unix that does this. So I think it is safe to clarify
the definition of current process group, to current process group
at the time of the wait function.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Alistair Francis <alistair23@gmail.com>
Cc: Zong Li <zongbox@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: GNU C Library <libc-alpha@sourceware.org>
Link: https://lore.kernel.org/r/20190814154400.6371-2-christian.brauner@ubuntu.com
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The powerpc version only supported 64 bit. Add some
code to switch decoding of fields during runtime so
we can kexec a 32 bit kernel from a 64 bit kernel and
vice versa.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
base was never assigned, so we can remove it.
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
It wasn't used anywhere, so lets drop it.
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
It's not used anywhere so just drop it.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
We're not using them, so we can drop the parsing.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
Change the order to have a 64/32/16 order, no functional change.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
Right now powerpc provides an implementation to read elf files
with the kexec_file_load() syscall. Make that available as a public
kexec interface so it can be re-used on other architectures.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Helge Deller <deller@gmx.de>
|
|
If we disable the compiler's auto-initialization feature, if
-fplugin-arg-structleak_plugin-byref or -ftrivial-auto-var-init=pattern
are disabled, arch_hw_breakpoint may be used before initialization after:
9a4903dde2c86 ("perf/hw_breakpoint: Split attribute parse and commit")
On our ARM platform, the struct step_ctrl in arch_hw_breakpoint, which
used to be zero-initialized by kzalloc(), may be used in
arch_install_hw_breakpoint() without initialization.
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alix Wu <alix.wu@mediatek.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Link: https://lkml.kernel.org/r/20190906060115.9460-1-mark-pk.tsai@mediatek.com
[ Minor edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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|
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
The following crash was observed:
Unable to handle kernel NULL pointer dereference at 0000000000000158
Internal error: Oops: 96000004 [#1] SMP
pc : resend_irqs+0x68/0xb0
lr : resend_irqs+0x64/0xb0
...
Call trace:
resend_irqs+0x68/0xb0
tasklet_action_common.isra.6+0x84/0x138
tasklet_action+0x2c/0x38
__do_softirq+0x120/0x324
run_ksoftirqd+0x44/0x60
smpboot_thread_fn+0x1ac/0x1e8
kthread+0x134/0x138
ret_from_fork+0x10/0x18
The reason for this is that the interrupt resend mechanism happens in soft
interrupt context, which is a asynchronous mechanism versus other
operations on interrupts. free_irq() does not take resend handling into
account. Thus, the irq descriptor might be already freed before the resend
tasklet is executed. resend_irqs() does not check the return value of the
interrupt descriptor lookup and derefences the return value
unconditionally.
1):
__setup_irq
irq_startup
check_irq_resend // activate softirq to handle resend irq
2):
irq_domain_free_irqs
irq_free_descs
free_desc
call_rcu(&desc->rcu, delayed_free_desc)
3):
__do_softirq
tasklet_action
resend_irqs
desc = irq_to_desc(irq)
desc->handle_irq(desc) // desc is NULL --> Ooops
Fix this by adding a NULL pointer check in resend_irqs() before derefencing
the irq descriptor.
Fixes: a4633adcdbc1 ("[PATCH] genirq: add genirq sw IRQ-retrigger")
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com
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|
The problem can be seen in the following two tests:
0: (bf) r3 = r10
1: (55) if r3 != 0x7b goto pc+0
2: (7a) *(u64 *)(r3 -8) = 0
3: (79) r4 = *(u64 *)(r10 -8)
..
0: (85) call bpf_get_prandom_u32#7
1: (bf) r3 = r10
2: (55) if r3 != 0x7b goto pc+0
3: (7b) *(u64 *)(r3 -8) = r0
4: (79) r4 = *(u64 *)(r10 -8)
When backtracking need to mark R4 it will mark slot fp-8.
But ST or STX into fp-8 could belong to the same block of instructions.
When backtracing is done the parent state may have fp-8 slot
as "unallocated stack". Which will cause verifier to warn
and incorrectly reject such programs.
Writes into stack via non-R10 register are rare. llvm always
generates canonical stack spill/fill.
For such pathological case fall back to conservative precision
tracking instead of rejecting.
Reported-by: syzbot+c8d66267fd2b5955287e@syzkaller.appspotmail.com
Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
|
|
Since BUG() and WARN() may use a trap (e.g. UD2 on x86) to
get the address where the BUG() has occurred, kprobes can not
do single-step out-of-line that instruction. So prohibit
probing on such address.
Without this fix, if someone put a kprobe on WARN(), the
kernel will crash with invalid opcode error instead of
outputing warning message, because kernel can not find
correct bug address.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N . Rao <naveen.n.rao@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/156750890133.19112.3393666300746167111.stgit@devnote2
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
logic and code
Thadeu Lima de Souza Cascardo reported that 'chrt' broke on recent kernels:
$ chrt -p $$
chrt: failed to get pid 26306's policy: Argument list too long
and he has root-caused the bug to the following commit increasing sched_attr
size and breaking sched_read_attr() into returning -EFBIG:
a509a7cd7974 ("sched/uclamp: Extend sched_setattr() to support utilization clamping")
The other, bigger bug is that the whole sched_getattr() and sched_read_attr()
logic of checking non-zero bits in new ABI components is arguably broken,
and pretty much any extension of the ABI will spuriously break the ABI.
That's way too fragile.
Instead implement the perf syscall's extensible ABI instead, which we
already implement on the sched_setattr() side:
- if user-attributes have the same size as kernel attributes then the
logic is unchanged.
- if user-attributes are larger than the kernel knows about then simply
skip the extra bits, but set attr->size to the (smaller) kernel size
so that tooling can (in principle) handle older kernel as well.
- if user-attributes are smaller than the kernel knows about then just
copy whatever user-space can accept.
Also clean up the whole logic:
- Simplify the code flow - there's no need for 'ret' for example.
- Standardize on 'kattr/uattr' and 'ksize/usize' naming to make sure we
always know which side we are dealing with.
- Why is it called 'read' when what it does is to copy to user? This
code is so far away from VFS read() semantics that the naming is
actively confusing. Name it sched_attr_copy_to_user() instead, which
mirrors other copy_to_user() functionality.
- Move the attr->size assignment from the head of sched_getattr() to the
sched_attr_copy_to_user() function. Nothing else within the kernel
should care about the size of the structure.
With these fixes the sched_getattr() syscall now nicely supports an
extensible ABI in both a forward and backward compatible fashion, and
will also fix the chrt bug.
As an added bonus the bogus -EFBIG return is removed as well, which as
Thadeu noted should have been -E2BIG to begin with.
Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: a509a7cd7974 ("sched/uclamp: Extend sched_setattr() to support utilization clamping")
Link: https://lkml.kernel.org/r/20190904075532.GA26751@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
The supported clamp indexes are defined in 'enum clamp_id', however, because
of the code logic in some of the first utilization clamping series version,
sometimes we needed to use 'unsigned int' to represent indices.
This is not more required since the final version of the uclamp_* APIs can
always use the proper enum uclamp_id type.
Fix it with a bulk rename now that we have all the bits merged.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-7-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
On updates of task group (TG) clamp values, ensure that these new values
are enforced on all RUNNABLE tasks of the task group, i.e. all RUNNABLE
tasks are immediately boosted and/or capped as requested.
Do that each time we update effective clamps from cpu_util_update_eff().
Use the *cgroup_subsys_state (css) to walk the list of tasks in each
affected TG and update their RUNNABLE tasks.
Update each task by using the same mechanism used for cpu affinity masks
updates, i.e. by taking the rq lock.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-6-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
When a task specific clamp value is configured via sched_setattr(2), this
value is accounted in the corresponding clamp bucket every time the task is
{en,de}qeued. However, when cgroups are also in use, the task specific
clamp values could be restricted by the task_group (TG) clamp values.
Update uclamp_cpu_inc() to aggregate task and TG clamp values. Every time a
task is enqueued, it's accounted in the clamp bucket tracking the smaller
clamp between the task specific value and its TG effective value. This
allows to:
1. ensure cgroup clamps are always used to restrict task specific requests,
i.e. boosted not more than its TG effective protection and capped at
least as its TG effective limit.
2. implement a "nice-like" policy, where tasks are still allowed to request
less than what enforced by their TG effective limits and protections
Do this by exploiting the concept of "effective" clamp, which is already
used by a TG to track parent enforced restrictions.
Apply task group clamp restrictions only to tasks belonging to a child
group. While, for tasks in the root group or in an autogroup, system
defaults are still enforced.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-5-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
The clamp values are not tunable at the level of the root task group.
That's for two main reasons:
- the root group represents "system resources" which are always
entirely available from the cgroup standpoint.
- when tuning/restricting "system resources" makes sense, tuning must
be done using a system wide API which should also be available when
control groups are not.
When a system wide restriction is available, cgroups should be aware of
its value in order to know exactly how much "system resources" are
available for the subgroups.
Utilization clamping supports already the concepts of:
- system defaults: which define the maximum possible clamp values
usable by tasks.
- effective clamps: which allows a parent cgroup to constraint (maybe
temporarily) its descendants without losing the information related
to the values "requested" from them.
Exploit these two concepts and bind them together in such a way that,
whenever system default are tuned, the new values are propagated to
(possibly) restrict or relax the "effective" value of nested cgroups.
When cgroups are in use, force an update of all the RUNNABLE tasks.
Otherwise, keep things simple and do just a lazy update next time each
task will be enqueued.
Do that since we assume a more strict resource control is required when
cgroups are in use. This allows also to keep "effective" clamp values
updated in case we need to expose them to user-space.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-4-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
In order to properly support hierarchical resources control, the cgroup
delegation model requires that attribute writes from a child group never
fail but still are locally consistent and constrained based on parent's
assigned resources. This requires to properly propagate and aggregate
parent attributes down to its descendants.
Implement this mechanism by adding a new "effective" clamp value for each
task group. The effective clamp value is defined as the smaller value
between the clamp value of a group and the effective clamp value of its
parent. This is the actual clamp value enforced on tasks in a task group.
Since it's possible for a cpu.uclamp.min value to be bigger than the
cpu.uclamp.max value, ensure local consistency by restricting each
"protection" (i.e. min utilization) with the corresponding "limit"
(i.e. max utilization).
Do that at effective clamps propagation to ensure all user-space write
never fails while still always tracking the most restrictive values.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
The cgroup CPU bandwidth controller allows to assign a specified
(maximum) bandwidth to the tasks of a group. However this bandwidth is
defined and enforced only on a temporal base, without considering the
actual frequency a CPU is running on. Thus, the amount of computation
completed by a task within an allocated bandwidth can be very different
depending on the actual frequency the CPU is running that task.
The amount of computation can be affected also by the specific CPU a
task is running on, especially when running on asymmetric capacity
systems like Arm's big.LITTLE.
With the availability of schedutil, the scheduler is now able
to drive frequency selections based on actual task utilization.
Moreover, the utilization clamping support provides a mechanism to
bias the frequency selection operated by schedutil depending on
constraints assigned to the tasks currently RUNNABLE on a CPU.
Giving the mechanisms described above, it is now possible to extend the
cpu controller to specify the minimum (or maximum) utilization which
should be considered for tasks RUNNABLE on a cpu.
This makes it possible to better defined the actual computational
power assigned to task groups, thus improving the cgroup CPU bandwidth
controller which is currently based just on time constraints.
Extend the CPU controller with a couple of new attributes uclamp.{min,max}
which allow to enforce utilization boosting and capping for all the
tasks in a group.
Specifically:
- uclamp.min: defines the minimum utilization which should be considered
i.e. the RUNNABLE tasks of this group will run at least at a
minimum frequency which corresponds to the uclamp.min
utilization
- uclamp.max: defines the maximum utilization which should be considered
i.e. the RUNNABLE tasks of this group will run up to a
maximum frequency which corresponds to the uclamp.max
utilization
These attributes:
a) are available only for non-root nodes, both on default and legacy
hierarchies, while system wide clamps are defined by a generic
interface which does not depends on cgroups. This system wide
interface enforces constraints on tasks in the root node.
b) enforce effective constraints at each level of the hierarchy which
are a restriction of the group requests considering its parent's
effective constraints. Root group effective constraints are defined
by the system wide interface.
This mechanism allows each (non-root) level of the hierarchy to:
- request whatever clamp values it would like to get
- effectively get only up to the maximum amount allowed by its parent
c) have higher priority than task-specific clamps, defined via
sched_setattr(), thus allowing to control and restrict task requests.
Add two new attributes to the cpu controller to collect "requested"
clamp values. Allow that at each non-root level of the hierarchy.
Keep it simple by not caring now about "effective" values computation
and propagation along the hierarchy.
Update sysctl_sched_uclamp_handler() to use the newly introduced
uclamp_mutex so that we serialize system default updates with cgroup
relate updates.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190822132811.31294-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
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SD_BALANCE_{FORK,EXEC} and SD_WAKE_AFFINE are stripped in sd_init()
for any sched domains with a NUMA distance greater than 2 hops
(RECLAIM_DISTANCE). The idea being that it's expensive to balance
across domains that far apart.
However, as is rather unfortunately explained in:
commit 32e45ff43eaf ("mm: increase RECLAIM_DISTANCE to 30")
the value for RECLAIM_DISTANCE is based on node distance tables from
2011-era hardware.
Current AMD EPYC machines have the following NUMA node distances:
node distances:
node 0 1 2 3 4 5 6 7
0: 10 16 16 16 32 32 32 32
1: 16 10 16 16 32 32 32 32
2: 16 16 10 16 32 32 32 32
3: 16 16 16 10 32 32 32 32
4: 32 32 32 32 10 16 16 16
5: 32 32 32 32 16 10 16 16
6: 32 32 32 32 16 16 10 16
7: 32 32 32 32 16 16 16 10
where 2 hops is 32.
The result is that the scheduler fails to load balance properly across
NUMA nodes on different sockets -- 2 hops apart.
For example, pinning 16 busy threads to NUMA nodes 0 (CPUs 0-7) and 4
(CPUs 32-39) like so,
$ numactl -C 0-7,32-39 ./spinner 16
causes all threads to fork and remain on node 0 until the active
balancer kicks in after a few seconds and forcibly moves some threads
to node 4.
Override node_reclaim_distance for AMD Zen.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suravee.Suthikulpanit@amd.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas.Lendacky@amd.com
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190808195301.13222-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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