Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- Make nohz housekeeping processing more permissive and less
intrusive to isolated CPUs
- Decouple CPU-bound workqueue acconting from the scheduler and move
it into the workqueue code.
- Optimize topology building
- Better handle quota and period overflows
- Add more RCU annotations
- Comment updates, misc cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
nohz_full: Allow the boot CPU to be nohz_full
sched/isolation: Require a present CPU in housekeeping mask
kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze
power/suspend: Add function to disable secondaries for suspend
sched/core: Allow the remote scheduler tick to be started on CPU0
sched/nohz: Run NOHZ idle load balancer on HK_FLAG_MISC CPUs
sched/debug: Fix spelling mistake "logaritmic" -> "logarithmic"
sched/topology: Update init_sched_domains() comment
cgroup/cpuset: Update stale generate_sched_domains() comments
sched/core: Check quota and period overflow at usec to nsec conversion
sched/core: Handle overflow in cpu_shares_write_u64
sched/rt: Check integer overflow at usec to nsec conversion
sched/core: Fix typo in comment
sched/core: Make some functions static
sched/core: Unify p->on_rq updates
sched/core: Remove ttwu_activate()
sched/core, workqueues: Distangle worker accounting from rq lock
sched/fair: Remove unneeded prototype of capacity_of()
sched/topology: Skip duplicate group rewrites in build_sched_groups()
sched/topology: Fix build_sched_groups() comment
...
Pull unified TLB flushing from Ingo Molnar:
"This contains the generic mmu_gather feature from Peter Zijlstra,
which is an all-arch unification of TLB flushing APIs, via the
following (broad) steps:
- enhance the <asm-generic/tlb.h> APIs to cover more arch details
- convert most TLB flushing arch implementations to the generic
<asm-generic/tlb.h> APIs.
- remove leftovers of per arch implementations
After this series every single architecture makes use of the unified
TLB flushing APIs"
* 'core-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mm/resource: Use resource_overlaps() to simplify region_intersects()
ia64/tlb: Eradicate tlb_migrate_finish() callback
asm-generic/tlb: Remove tlb_table_flush()
asm-generic/tlb: Remove tlb_flush_mmu_free()
asm-generic/tlb: Remove CONFIG_HAVE_GENERIC_MMU_GATHER
asm-generic/tlb: Remove arch_tlb*_mmu()
s390/tlb: Convert to generic mmu_gather
asm-generic/tlb: Introduce CONFIG_HAVE_MMU_GATHER_NO_GATHER=y
arch/tlb: Clean up simple architectures
um/tlb: Convert to generic mmu_gather
sh/tlb: Convert SH to generic mmu_gather
ia64/tlb: Convert to generic mmu_gather
arm/tlb: Convert to generic mmu_gather
asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATE
asm-generic/tlb, ia64: Conditionally provide tlb_migrate_finish()
asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm()
asm-generic/tlb, arch: Provide generic tlb_flush() based on flush_tlb_range()
asm-generic/tlb, arch: Provide generic VIPT cache flush
asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
asm-generic/tlb: Provide a comment
During housekeeping mask setup, currently a possible CPU is required.
That does not guarantee the CPU would be available at boot time, so
check to ensure that at least one present CPU is in the mask.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lkml.kernel.org/r/20190411033448.20842-5-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This has no effect yet because CPU0 will always be a housekeeping CPU
until a later change.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lkml.kernel.org/r/20190411033448.20842-2-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the error return path from kobject_init_and_add() is not
followed by a call to kobject_put() - which means we are leaking
the kobject.
Fix it by adding a call to kobject_put() in the error path of
kobject_init_and_add().
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: http://lkml.kernel.org/r/20190430001144.24890-1-tobin@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The NOHZ idle balancer runs on the lowest idle CPU. This can
interfere with isolated CPUs, so confine it to HK_FLAG_MISC
housekeeping CPUs.
HK_FLAG_SCHED is not used for this because it is not set anywhere
at the moment. This could be folded into HK_FLAG_SCHED once that
option is fixed.
The problem was observed with increased jitter on an application
running on CPU0, caused by NOHZ idle load balancing being run on
CPU1 (an SMT sibling).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.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/20190412042613.28930-1-npiggin@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched_clock_cpu() may not be consistent between CPUs. If a task
migrates to another CPU, then se.exec_start is set to that CPU's
rq_clock_task() by update_stats_curr_start(). Specifically, the new
value might be before the old value due to clock skew.
So then if in numa_get_avg_runtime() the expression:
'now - p->last_task_numa_placement'
ends up as -1, then the divider '*period + 1' in task_numa_placement()
is 0 and things go bang. Similar to update_curr(), check if time goes
backwards to avoid this.
[ peterz: Wrote new changelog. ]
[ mingo: Tweaked the code comment. ]
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cj.chengjian@huawei.com
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20190425080016.GX11158@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Large values could overflow u64 and pass following sanity checks.
# echo 18446744073750000 > cpu.cfs_period_us
# cat cpu.cfs_period_us
40448
# echo 18446744073750000 > cpu.cfs_quota_us
# cat cpu.cfs_quota_us
40448
After this patch they will fail with -EINVAL.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125502079.293431.3947497929372138600.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Bit shift in scale_load() could overflow shares. This patch saturates
it to MAX_SHARES like following sched_group_set_shares().
Example:
# echo 9223372036854776832 > cpu.shares
# cat cpu.shares
Before patch: 1024
After pattch: 262144
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125501891.293431.3345233332801109696.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix these sparse warnings:
kernel/sched/core.c:6577:11: warning: symbol 'min_cfs_quota_period' was not declared. Should it be static?
kernel/sched/core.c:6657:5: warning: symbol 'tg_set_cfs_quota' was not declared. Should it be static?
kernel/sched/core.c:6670:6: warning: symbol 'tg_get_cfs_quota' was not declared. Should it be static?
kernel/sched/core.c:6683:5: warning: symbol 'tg_set_cfs_period' was not declared. Should it be static?
kernel/sched/core.c:6693:6: warning: symbol 'tg_get_cfs_period' was not declared. Should it be static?
kernel/sched/fair.c:2596:6: warning: symbol 'task_tick_numa' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190418144713.34332-1-yuehaibing@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Almost all {,de}activate_task() invocations pair with p->on_rq
updates, the exception being the usage in rt/deadline which hold both
rq locks and therefore don't strictly need to set
TASK_ON_RQ_MIGRATING, but it is harmless if we do anyway.
Put the updates in {,de}activate_task() and cut down on repetition.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After the removal of try_to_wake_up_local(), there is only one user of
ttwu_activate() left, and since it is a trivial function, remove it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The worker accounting for CPU bound workers is plugged into the core
scheduler code and the wakeup code. This is not a hard requirement and
can be avoided by keeping track of the state in the workqueue code
itself.
Keep track of the sleeping state in the worker itself and call the
notifier before entering the core scheduler. There might be false
positives when the task is woken between that call and actually
scheduling, but that's not really different from scheduling and being
woken immediately after switching away. When nr_running is updated when
the task is retunrning from schedule() then it is later compared when it
is done from ttwu().
[ bigeasy: preempt_disable() around wq_worker_sleeping() by Daniel Bristot de Oliveira ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/ad2b29b5715f970bffc1a7026cabd6ff0b24076a.1532952814.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
syzbot reported the following warning:
[ ] WARNING: CPU: 4 PID: 17089 at kernel/sched/deadline.c:255 task_non_contending+0xae0/0x1950
line 255 of deadline.c is:
WARN_ON(hrtimer_active(&dl_se->inactive_timer));
in task_non_contending().
Unfortunately, in some cases (for example, a deadline task
continuosly blocking and waking immediately) it can happen that
a task blocks (and task_non_contending() is called) while the
0-lag timer is still active.
In this case, the safest thing to do is to immediately decrease
the running bandwidth of the task, without trying to re-arm the 0-lag timer.
Signed-off-by: luca abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: chengjian (D) <cj.chengjian@huawei.com>
Link: https://lkml.kernel.org/r/20190325131530.34706-1-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With extremely short cfs_period_us setting on a parent task group with a large
number of children the for loop in sched_cfs_period_timer() can run until the
watchdog fires. There is no guarantee that the call to hrtimer_forward_now()
will ever return 0. The large number of children can make
do_sched_cfs_period_timer() take longer than the period.
NMI watchdog: Watchdog detected hard LOCKUP on cpu 24
RIP: 0010:tg_nop+0x0/0x10
<IRQ>
walk_tg_tree_from+0x29/0xb0
unthrottle_cfs_rq+0xe0/0x1a0
distribute_cfs_runtime+0xd3/0xf0
sched_cfs_period_timer+0xcb/0x160
? sched_cfs_slack_timer+0xd0/0xd0
__hrtimer_run_queues+0xfb/0x270
hrtimer_interrupt+0x122/0x270
smp_apic_timer_interrupt+0x6a/0x140
apic_timer_interrupt+0xf/0x20
</IRQ>
To prevent this we add protection to the loop that detects when the loop has run
too many times and scales the period and quota up, proportionally, so that the timer
can complete before then next period expires. This preserves the relative runtime
quota while preventing the hard lockup.
A warning is issued reporting this state and the new values.
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Ben Segall <bsegall@google.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/20190319130005.25492-1-pauld@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The prototype of that function was already hoisted up in:
commit 3b1baa6496 ("sched/fair: Add 'group_misfit_task' load-balance type")
but that seems to have been missed. Get rid of the extra prototype.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Quentin Perret <quentin.perret@arm.com>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Fixes: 2802bf3cd9 ("sched/fair: Add over-utilization/tipping point indicator")
Link: http://lkml.kernel.org/r/20190416140621.19884-1-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While staring at build_sched_domains(), I realized that get_group()
does several duplicate (thus useless) writes.
If you take the Arm Juno r0 (LITTLEs = [0, 3, 4, 5], bigs = [1, 2]), the
sched_group build flow would look like this:
('MC[cpu]->sg' means 'per_cpu_ptr(&tl->data->sg, cpu)' with 'tl == MC')
build_sched_groups(MC[CPU0]->sd, CPU0)
get_group(0) -> MC[CPU0]->sg
get_group(3) -> MC[CPU3]->sg
get_group(4) -> MC[CPU4]->sg
get_group(5) -> MC[CPU5]->sg
build_sched_groups(DIE[CPU0]->sd, CPU0)
get_group(0) -> DIE[CPU0]->sg
get_group(1) -> DIE[CPU1]->sg <=================+
|
build_sched_groups(MC[CPU1]->sd, CPU1) |
get_group(1) -> MC[CPU1]->sg |
get_group(2) -> MC[CPU2]->sg |
|
build_sched_groups(DIE[CPU1]->sd, CPU1) ^
get_group(1) -> DIE[CPU1]->sg } We've set up these two up here!
get_group(3) -> DIE[CPU0]->sg }
From this point on, we will only use sched_groups that have been
previously visited & initialized. The only new operation will
be which group pointer we affect to sd->groups.
On the Juno r0 we get 32 get_group() calls, every single one of them
writing to a sched_group->cpumask. However, all of the data structures
we need are set up after 8 visits (see above).
Return early from get_group() if we've already visited (and thus
initialized) the sched_group we're looking at. Overlapping domains
are not affected as they do not use build_sched_groups().
Tested on a Juno and a 2 * (Xeon E5-2690) system.
( FWIW I initially checked the refs for both sg && sg->sgc, but figured if
they weren't both 0 or > 1 then something must have gone wrong, so I
threw in a WARN_ON(). )
No change in functionality intended.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment was introduced (pre 2.6.12) by:
8a7a2318dc07 ("[PATCH] sched: consolidate sched domains")
and referred to sched_group->cpu_power. This was folded into
sched_group->sched_group_power in
commit 9c3f75cbd1 ("sched: Break out cpu_power from the sched_group structure")
The comment was then updated in:
ced549fa5f ("sched: Remove remaining dubious usage of "power"")
but should have replaced "sg->cpu_capacity" with
"sg->sched_group_capacity". Do that now.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: qais.yousef@arm.com
Link: http://lkml.kernel.org/r/20190409173546.4747-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix these sparse warnigs:
kernel/sched/fair.c:3570:6: warning: symbol 'sync_entity_load_avg' was not declared. Should it be static?
kernel/sched/fair.c:3583:6: warning: symbol 'remove_entity_load_avg' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190320133839.21392-1-yuehaibing@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This fixes the following sparse errors in sched/fair.c:
fair.c:6506:14: error: incompatible types in comparison expression
fair.c:8642:21: error: incompatible types in comparison expression
Using __rcu will also help sparse catch any future bugs.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ From an RCU perspective. ]
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-5-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recently I added an RCU annotation check to rcu_assign_pointer(). All
pointers assigned to RCU protected data are to be annotated with __rcu
inorder to be able to use rcu_assign_pointer() similar to checks in
other RCU APIs.
This resulted in a sparse error:
kernel//sched/cpufreq.c:41:9: sparse: error: incompatible types in comparison expression (different address spaces)
Fix this by annotating cpufreq_update_util_data pointer with __rcu. This
will also help sparse catch any future RCU misuage bugs.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ From an RCU perspective. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-2-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Only ia64-sn2 uses this as an optimization, and there it is of
questionable correctness due to the mm_users==1 test.
Remove it entirely.
No change in behavior intended.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A NULL pointer dereference bug was reported on a distribution kernel but
the same issue should be present on mainline kernel. It occured on s390
but should not be arch-specific. A partial oops looks like:
Unable to handle kernel pointer dereference in virtual kernel address space
...
Call Trace:
...
try_to_wake_up+0xfc/0x450
vhost_poll_wakeup+0x3a/0x50 [vhost]
__wake_up_common+0xbc/0x178
__wake_up_common_lock+0x9e/0x160
__wake_up_sync_key+0x4e/0x60
sock_def_readable+0x5e/0x98
The bug hits any time between 1 hour to 3 days. The dereference occurs
in update_cfs_rq_h_load when accumulating h_load. The problem is that
cfq_rq->h_load_next is not protected by any locking and can be updated
by parallel calls to task_h_load. Depending on the compiler, code may be
generated that re-reads cfq_rq->h_load_next after the check for NULL and
then oops when reading se->avg.load_avg. The dissassembly showed that it
was possible to reread h_load_next after the check for NULL.
While this does not appear to be an issue for later compilers, it's still
an accident if the correct code is generated. Full locking in this path
would have high overhead so this patch uses READ_ONCE to read h_load_next
only once and check for NULL before dereferencing. It was confirmed that
there were no further oops after 10 days of testing.
As Peter pointed out, it is also necessary to use WRITE_ONCE() to avoid any
potential problems with store tearing.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Fixes: 685207963b ("sched: Move h_load calculation to task_h_load()")
Link: https://lkml.kernel.org/r/20190319123610.nsivgf3mjbjjesxb@techsingularity.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler updates from Thomas Gleixner:
"Third more careful attempt for this set of fixes:
- Prevent a 32bit math overflow in the cpufreq code
- Fix a buffer overflow when scanning the cgroup2 cpu.max property
- A set of fixes for the NOHZ scheduler logic to prevent waking up
CPUs even if the capacity of the busy CPUs is sufficient along with
other tweaks optimizing the behaviour for asymmetric systems
(big/little)"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Skip LLC NOHZ logic for asymmetric systems
sched/fair: Tune down misfit NOHZ kicks
sched/fair: Comment some nohz_balancer_kick() kick conditions
sched/core: Fix buffer overflow in cgroup2 property cpu.max
sched/cpufreq: Fix 32-bit math overflow
The LLC NOHZ condition will become true as soon as >=2 CPUs in a
single LLC domain are busy. On big.LITTLE systems, this translates to
two or more CPUs of a "cluster" (big or LITTLE) being busy.
Issuing a NOHZ kick in these conditions isn't desired for asymmetric
systems, as if the busy CPUs can provide enough compute capacity to
the running tasks, then we can leave the NOHZ CPUs in peace.
Skip the LLC NOHZ condition for asymmetric systems, and rely on
nr_running & capacity checks to trigger NOHZ kicks when the system
actually needs them.
Suggested-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In this commit:
3b1baa6496 ("sched/fair: Add 'group_misfit_task' load-balance type")
we set rq->misfit_task_load whenever the current running task has a
utilization greater than 80% of rq->cpu_capacity. A non-zero value in
this field enables misfit load balancing.
However, if the task being looked at is already running on a CPU of
highest capacity, there's nothing more we can do for it. We can
currently spot this in update_sd_pick_busiest(), which prevents us
from selecting a sched_group of group_type == group_misfit_task as the
busiest group, but we don't do any of that in nohz_balancer_kick().
This means that we could repeatedly kick NOHZ CPUs when there's no
improvements in terms of load balance to be done.
Introduce a check_misfit_status() helper that returns true iff there
is a CPU in the system that could give more CPU capacity to a rq's
misfit task - IOW, there exists a CPU of higher capacity_orig or the
rq's CPU is severely pressured by rt/IRQ.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-3-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We now have a comment explaining the first sched_domain based NOHZ kick,
so might as well comment them all.
While at it, unwrap a line that fits under 80 characters.
Co-authored-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dietmar.Eggemann@arm.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190211175946.4961-2-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Vincent Wang reported that get_next_freq() has a mult overflow bug on
32-bit platforms in the IOWAIT boost case, since in that case {util,max}
are in freq units instead of capacity units.
Solve this by moving the IOWAIT boost to capacity units. And since this
means @max is constant; simplify the code.
Reported-by: Vincent Wang <vincent.wang@unisoc.com>
Tested-by: Vincent Wang <vincent.wang@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190305083202.GU32494@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge misc updates from Andrew Morton:
- a few misc things
- ocfs2 updates
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (159 commits)
tools/testing/selftests/proc/proc-self-syscall.c: remove duplicate include
proc: more robust bulk read test
proc: test /proc/*/maps, smaps, smaps_rollup, statm
proc: use seq_puts() everywhere
proc: read kernel cpu stat pointer once
proc: remove unused argument in proc_pid_lookup()
fs/proc/thread_self.c: code cleanup for proc_setup_thread_self()
fs/proc/self.c: code cleanup for proc_setup_self()
proc: return exit code 4 for skipped tests
mm,mremap: bail out earlier in mremap_to under map pressure
mm/sparse: fix a bad comparison
mm/memory.c: do_fault: avoid usage of stale vm_area_struct
writeback: fix inode cgroup switching comment
mm/huge_memory.c: fix "orig_pud" set but not used
mm/hotplug: fix an imbalance with DEBUG_PAGEALLOC
mm/memcontrol.c: fix bad line in comment
mm/cma.c: cma_declare_contiguous: correct err handling
mm/page_ext.c: fix an imbalance with kmemleak
mm/compaction: pass pgdat to too_many_isolated() instead of zone
mm: remove zone_lru_lock() function, access ->lru_lock directly
...
Pull scheduler updates from Ingo Molnar:
"The main changes in this cycle were:
- refcount conversions
- Solve the rq->leaf_cfs_rq_list can of worms for real.
- improve power-aware scheduling
- add sysctl knob for Energy Aware Scheduling
- documentation updates
- misc other changes"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
kthread: Do not use TIMER_IRQSAFE
kthread: Convert worker lock to raw spinlock
sched/fair: Use non-atomic cpumask_{set,clear}_cpu()
sched/fair: Remove unused 'sd' parameter from select_idle_smt()
sched/wait: Use freezable_schedule() when possible
sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block
sched/fair: Explain LLC nohz kick condition
sched/fair: Simplify nohz_balancer_kick()
sched/topology: Fix percpu data types in struct sd_data & struct s_data
sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
sched/fair: Fix O(nr_cgroups) in the load balancing path
sched/fair: Optimize update_blocked_averages()
sched/fair: Fix insertion in rq->leaf_cfs_rq_list
sched/fair: Add tmp_alone_branch assertion
sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
sched/pelt: Skip updating util_est when utilization is higher than CPU's capacity
sched/fair: Update scale invariance of PELT
sched/fair: Move the rq_of() helper function
sched/core: Convert task_struct.stack_refcount to refcount_t
...
Pull locking updates from Ingo Molnar:
"The biggest part of this tree is the new auto-generated atomics API
wrappers by Mark Rutland.
The primary motivation was to allow instrumentation without uglifying
the primary source code.
The linecount increase comes from adding the auto-generated files to
the Git space as well:
include/asm-generic/atomic-instrumented.h | 1689 ++++++++++++++++--
include/asm-generic/atomic-long.h | 1174 ++++++++++---
include/linux/atomic-fallback.h | 2295 +++++++++++++++++++++++++
include/linux/atomic.h | 1241 +------------
I preferred this approach, so that the full call stack of the (already
complex) locking APIs is still fully visible in 'git grep'.
But if this is excessive we could certainly hide them.
There's a separate build-time mechanism to determine whether the
headers are out of date (they should never be stale if we do our job
right).
Anyway, nothing from this should be visible to regular kernel
developers.
Other changes:
- Add support for dynamic keys, which removes a source of false
positives in the workqueue code, among other things (Bart Van
Assche)
- Updates to tools/memory-model (Andrea Parri, Paul E. McKenney)
- qspinlock, wake_q and lockdep micro-optimizations (Waiman Long)
- misc other updates and enhancements"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
locking/lockdep: Shrink struct lock_class_key
locking/lockdep: Add module_param to enable consistency checks
lockdep/lib/tests: Test dynamic key registration
lockdep/lib/tests: Fix run_tests.sh
kernel/workqueue: Use dynamic lockdep keys for workqueues
locking/lockdep: Add support for dynamic keys
locking/lockdep: Verify whether lock objects are small enough to be used as class keys
locking/lockdep: Check data structure consistency
locking/lockdep: Reuse lock chains that have been freed
locking/lockdep: Fix a comment in add_chain_cache()
locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count()
locking/lockdep: Reuse list entries that are no longer in use
locking/lockdep: Free lock classes that are no longer in use
locking/lockdep: Update two outdated comments
locking/lockdep: Make it easy to detect whether or not inside a selftest
locking/lockdep: Split lockdep_free_key_range() and lockdep_reset_lock()
locking/lockdep: Initialize the locks_before and locks_after lists earlier
locking/lockdep: Make zap_class() remove all matching lock order entries
locking/lockdep: Reorder struct lock_class members
locking/lockdep: Avoid that add_chain_cache() adds an invalid chain to the cache
...
Compaction is inherently race-prone as a suitable page freed during
compaction can be allocated by any parallel task. This patch uses a
capture_control structure to isolate a page immediately when it is freed
by a direct compactor in the slow path of the page allocator. The
intent is to avoid redundant scanning.
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Amean fault-both-1 0.00 ( 0.00%) 0.00 * 0.00%*
Amean fault-both-3 2582.11 ( 0.00%) 2563.68 ( 0.71%)
Amean fault-both-5 4500.26 ( 0.00%) 4233.52 ( 5.93%)
Amean fault-both-7 5819.53 ( 0.00%) 6333.65 ( -8.83%)
Amean fault-both-12 9321.18 ( 0.00%) 9759.38 ( -4.70%)
Amean fault-both-18 9782.76 ( 0.00%) 10338.76 ( -5.68%)
Amean fault-both-24 15272.81 ( 0.00%) 13379.55 * 12.40%*
Amean fault-both-30 15121.34 ( 0.00%) 16158.25 ( -6.86%)
Amean fault-both-32 18466.67 ( 0.00%) 18971.21 ( -2.73%)
Latency is only moderately affected but the devil is in the details. A
closer examination indicates that base page fault latency is reduced but
latency of huge pages is increased as it takes creater care to succeed.
Part of the "problem" is that allocation success rates are close to 100%
even when under pressure and compaction gets harder
5.0.0-rc1 5.0.0-rc1
selective-v3r17 capture-v3r19
Percentage huge-3 96.70 ( 0.00%) 98.23 ( 1.58%)
Percentage huge-5 96.99 ( 0.00%) 95.30 ( -1.75%)
Percentage huge-7 94.19 ( 0.00%) 97.24 ( 3.24%)
Percentage huge-12 94.95 ( 0.00%) 97.35 ( 2.53%)
Percentage huge-18 96.74 ( 0.00%) 97.30 ( 0.58%)
Percentage huge-24 97.07 ( 0.00%) 97.55 ( 0.50%)
Percentage huge-30 95.69 ( 0.00%) 98.50 ( 2.95%)
Percentage huge-32 96.70 ( 0.00%) 99.27 ( 2.65%)
And scan rates are reduced as expected by 6% for the migration scanner
and 29% for the free scanner indicating that there is less redundant
work.
Compaction migrate scanned 20815362 19573286
Compaction free scanned 16352612 11510663
[mgorman@techsingularity.net: remove redundant check]
Link: http://lkml.kernel.org/r/20190201143853.GH9565@techsingularity.net
Link: http://lkml.kernel.org/r/20190118175136.31341-23-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Replace all open encodings for NUMA_NO_NODE", v3.
All these places for replacement were found by running the following
grep patterns on the entire kernel code. Please let me know if this
might have missed some instances. This might also have replaced some
false positives. I will appreciate suggestions, inputs and review.
1. git grep "nid == -1"
2. git grep "node == -1"
3. git grep "nid = -1"
4. git grep "node = -1"
This patch (of 2):
At present there are multiple places where invalid node number is
encoded as -1. Even though implicitly understood it is always better to
have macros in there. Replace these open encodings for an invalid node
number with the global macro NUMA_NO_NODE. This helps remove NUMA
related assumptions like 'invalid node' from various places redirecting
them to a common definition.
Link: http://lkml.kernel.org/r/1545127933-10711-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [ixgbe]
Acked-by: Jens Axboe <axboe@kernel.dk> [mtip32xx]
Acked-by: Vinod Koul <vkoul@kernel.org> [dmaengine.c]
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Doug Ledford <dledford@redhat.com> [drivers/infiniband]
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull year 2038 updates from Thomas Gleixner:
"Another round of changes to make the kernel ready for 2038. After lots
of preparatory work this is the first set of syscalls which are 2038
safe:
403 clock_gettime64
404 clock_settime64
405 clock_adjtime64
406 clock_getres_time64
407 clock_nanosleep_time64
408 timer_gettime64
409 timer_settime64
410 timerfd_gettime64
411 timerfd_settime64
412 utimensat_time64
413 pselect6_time64
414 ppoll_time64
416 io_pgetevents_time64
417 recvmmsg_time64
418 mq_timedsend_time64
419 mq_timedreceiv_time64
420 semtimedop_time64
421 rt_sigtimedwait_time64
422 futex_time64
423 sched_rr_get_interval_time64
The syscall numbers are identical all over the architectures"
* 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
riscv: Use latest system call ABI
checksyscalls: fix up mq_timedreceive and stat exceptions
unicore32: Fix __ARCH_WANT_STAT64 definition
asm-generic: Make time32 syscall numbers optional
asm-generic: Drop getrlimit and setrlimit syscalls from default list
32-bit userspace ABI: introduce ARCH_32BIT_OFF_T config option
compat ABI: use non-compat openat and open_by_handle_at variants
y2038: add 64-bit time_t syscalls to all 32-bit architectures
y2038: rename old time and utime syscalls
y2038: remove struct definition redirects
y2038: use time32 syscall names on 32-bit
syscalls: remove obsolete __IGNORE_ macros
y2038: syscalls: rename y2038 compat syscalls
x86/x32: use time64 versions of sigtimedwait and recvmmsg
timex: change syscalls to use struct __kernel_timex
timex: use __kernel_timex internally
sparc64: add custom adjtimex/clock_adjtime functions
time: fix sys_timer_settime prototype
time: Add struct __kernel_timex
time: make adjtime compat handling available for 32 bit
...
Daniel Borkmann says:
====================
pull-request: bpf-next 2019-03-04
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Add AF_XDP support to libbpf. Rationale is to facilitate writing
AF_XDP applications by offering higher-level APIs that hide many
of the details of the AF_XDP uapi. Sample programs are converted
over to this new interface as well, from Magnus.
2) Introduce a new cant_sleep() macro for annotation of functions
that cannot sleep and use it in BPF_PROG_RUN() to assert that
BPF programs run under preemption disabled context, from Peter.
3) Introduce per BPF prog stats in order to monitor the usage
of BPF; this is controlled by kernel.bpf_stats_enabled sysctl
knob where monitoring tools can make use of this to efficiently
determine the average cost of programs, from Alexei.
4) Split up BPF selftest's test_progs similarly as we already
did with test_verifier. This allows to further reduce merge
conflicts in future and to get more structure into our
quickly growing BPF selftest suite, from Stanislav.
5) Fix a bug in BTF's dedup algorithm which can cause an infinite
loop in some circumstances; also various BPF doc fixes and
improvements, from Andrii.
6) Various BPF sample cleanups and migration to libbpf in order
to further isolate the old sample loader code (so we can get
rid of it at some point), from Jakub.
7) Add a new BPF helper for BPF cgroup skb progs that allows
to set ECN CE code point and a Host Bandwidth Manager (HBM)
sample program for limiting the bandwidth used by v2 cgroups,
from Lawrence.
8) Enable write access to skb->queue_mapping from tc BPF egress
programs in order to let BPF pick TX queue, from Jesper.
9) Fix a bug in BPF spinlock handling for map-in-map which did
not propagate spin_lock_off to the meta map, from Yonghong.
10) Fix a bug in the new per-CPU BPF prog counters to properly
initialize stats for each CPU, from Eric.
11) Add various BPF helper prototypes to selftest's bpf_helpers.h,
from Willem.
12) Fix various BPF samples bugs in XDP and tracing progs,
from Toke, Daniel and Yonghong.
13) Silence preemption splat in test_bpf after BPF_PROG_RUN()
enforces it now everywhere, from Anders.
14) Fix a signedness bug in libbpf's btf_dedup_ref_type() to
get error handling working, from Dan.
15) Fix bpftool documentation and auto-completion with regards
to stream_{verdict,parser} attach types, from Alban.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
We've been seeing hard-to-trigger psi crashes when running inside VM
instances:
divide error: 0000 [#1] SMP PTI
Modules linked in: [...]
CPU: 0 PID: 212 Comm: kworker/0:2 Not tainted 4.16.18-119_fbk9_3817_gfe944c98d695 #119
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
Workqueue: events psi_clock
RIP: 0010:psi_update_stats+0x270/0x490
RSP: 0018:ffffc90001117e10 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8800a35a13f8
RDX: 0000000000000000 RSI: ffff8800a35a1340 RDI: 0000000000000000
RBP: 0000000000000658 R08: ffff8800a35a1470 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000f8502
FS: 0000000000000000(0000) GS:ffff88023fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbe370fa000 CR3: 00000000b1e3a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
psi_clock+0x12/0x50
process_one_work+0x1e0/0x390
worker_thread+0x2b/0x3c0
? rescuer_thread+0x330/0x330
kthread+0x113/0x130
? kthread_create_worker_on_cpu+0x40/0x40
? SyS_exit_group+0x10/0x10
ret_from_fork+0x35/0x40
Code: 48 0f 47 c7 48 01 c2 45 85 e4 48 89 16 0f 85 e6 00 00 00 4c 8b 49 10 4c 8b 51 08 49 69 d9 f2 07 00 00 48 6b c0 64 4c 8b 29 31 d2 <48> f7 f7 49 69 d5 8d 06 00 00 48 89 c5 4c 69 f0 00 98 0b 00 48
The Code-line points to `period` being 0 inside update_stats(), and we
divide by that when calculating that period's pressure percentage.
The elapsed period should never be 0. The reason this can happen is due
to an off-by-one in the idle time / missing period calculation combined
with a coarse sched_clock() in the virtual machine.
The target time for aggregation is advanced into the future on a fixed
grid to prevent clock drift. So when an aggregation runs after some idle
period, we can not just set it to "now + psi_period", but have to
calculate the downtime and advance the target time relative to itself.
However, if the aggregator was disabled exactly one psi_period (ns), we
drop one idle period in the calculation due to a > when we should do >=.
In that case, next_update will be advanced from 'now - psi_period' to
'now' when it should be moved to 'now + psi_period'. The run finishes
with last_update == next_update == sched_clock().
With hardware clocks, this exact nanosecond match isn't likely in the
first place; but if it does happen, the clock will still have moved on and
the period non-zero by the time the worker runs. A pointlessly short
period, but besides the extra work, no harm no foul. However, a slow
sched_clock() like we have on VMs might not have advanced either by the
time the worker runs again. And when we calculate the elapsed period, the
result, our pressure divisor, will be 0. Ouch.
Fix this by correctly handling the situation when the elapsed time between
aggregation runs is precisely two periods, and advance the expiration
timestamp correctly to period into the future.
Link: http://lkml.kernel.org/r/20190214193157.15788-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Łukasz Siudut <lsiudut@fb.com
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce cant_sleep() macro for annotation of functions that
cannot sleep.
Use it in BPF_PROG_RUN to catch execution of BPF programs in
preemptable context.
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull the latest RCU tree from Paul E. McKenney:
- Additional cleanups after RCU flavor consolidation
- Grace-period forward-progress cleanups and improvements
- Documentation updates
- Miscellaneous fixes
- spin_is_locked() conversions to lockdep
- SPDX changes to RCU source and header files
- SRCU updates
- Torture-test updates, including nolibc updates and moving
nolibc to tools/include
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The cpumasks updated here are not subject to concurrency and using
atomic bitops for them is pointless and expensive. Use the non-atomic
variants instead.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/2e2a10f84b9049a81eef94ed6d5989447c21e34a.1549963617.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The 'sd' parameter isn't getting used in select_idle_smt(), drop it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/f91c5e118183e79d4a982e9ac4ce5e47948f6c1b.1549536337.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The comment block for that function lists the heuristics for
triggering a nohz kick, but the most recent ones (blocked load
updates, misfit) aren't included, and some of them (LLC nohz logic,
asym packing) are no longer in sync with the code.
The conditions are either simple enough or properly commented, so get
rid of that list instead of letting it grow.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar.Eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: morten.rasmussen@arm.com
Cc: vincent.guittot@linaro.org
Link: https://lkml.kernel.org/r/20190117153411.2390-4-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
