- 10 Sep, 2018 25 commits
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Vincent Guittot authored
With: commit 2d4056fa ("sched/numa: Remove numa_has_capacity()") the local variables 'smt', 'cpus' and 'capacity' and their results are not used anymore in numa_has_capacity() Remove this unused code. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> 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> Link: http://lkml.kernel.org/r/1535548752-4434-2-git-send-email-vincent.guittot@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Peter Zijlstra authored
LLVM has a warning that tags expressions like: if (foo && non-bool-const) This pattern triggers for CONFIG_SCHED_DEBUG=n where sched_feat() ends up being whatever bit we select. Avoid the warning with an explicit cast to bool. Reported-by: Philipp Klocke <philipp97kl@gmail.com> Tested-by: Nick Desaulniers <ndesaulniers@google.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: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
The 'prefer sibling' sched_domain flag is intended to encourage spreading tasks to sibling sched_domain to take advantage of more caches and core for SMT systems. It has recently been changed to be on all non-NUMA topology level. However, spreading across domains with CPU capacity asymmetry isn't desirable, e.g. spreading from high capacity to low capacity CPUs even if high capacity CPUs aren't overutilized might give access to more cache but the CPU will be slower and possibly lead to worse overall throughput. To prevent this, we need to remove SD_PREFER_SIBLING on the sched_domain level immediately below SD_ASYM_CPUCAPACITY. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-13-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Chris Redpath authored
When lower capacity CPUs are load balancing and considering to pull something from a higher capacity group, we should not pull tasks from a CPU with only one task running as this is guaranteed to impede progress for that task. If there is more than one task running, load balance in the higher capacity group would have already made any possible moves to resolve imbalance and we should make better use of system compute capacity by moving a task if we still have more than one running. Signed-off-by: Chris Redpath <chris.redpath@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-11-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Valentin Schneider authored
Idle balance is a great opportunity to pull a misfit task. However, there are scenarios where misfit tasks are present but idle balance is prevented by the overload flag. A good example of this is a workload of n identical tasks. Let's suppose we have a 2+2 Arm big.LITTLE system. We then spawn 4 fairly CPU-intensive tasks - for the sake of simplicity let's say they are just CPU hogs, even when running on big CPUs. They are identical tasks, so on an SMP system they should all end at (roughly) the same time. However, in our case the LITTLE CPUs are less performing than the big CPUs, so tasks running on the LITTLEs will have a longer completion time. This means that the big CPUs will complete their work earlier, at which point they should pull the tasks from the LITTLEs. What we want to happen is summarized as follows: a,b,c,d are our CPU-hogging tasks _ signifies idling LITTLE_0 | a a a a _ _ LITTLE_1 | b b b b _ _ ---------|------------- big_0 | c c c c a a big_1 | d d d d b b ^ ^ Tasks end on the big CPUs, idle balance happens and the misfit tasks are pulled straight away This however won't happen, because currently the overload flag is only set when there is any CPU that has more than one runnable task - which may very well not be the case here if our CPU-hogging workload is all there is to run. As such, this commit sets the overload flag in update_sg_lb_stats when a group is flagged as having a misfit task. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-10-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Valentin Schneider authored
This variable can be read and set locklessly within update_sd_lb_stats(). As such, READ/WRITE_ONCE() are added to make sure nothing terribly wrong can happen because of the compiler. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-9-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Valentin Schneider authored
sizeof(_Bool) is implementation defined, so let's just go with 'int' as is done for other structures e.g. sched_domain_shared->has_idle_cores. The local 'overload' variable used in update_sd_lb_stats can remain bool, as it won't impact any struct layout and can be assigned to the root_domain field. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-8-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Valentin Schneider authored
This variable is entirely local to update_sd_lb_stats, so we can safely change its type and slightly clean up its initialisation. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-7-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Valentin Schneider authored
There already are a few conditions in nohz_kick_needed() to ensure a nohz kick is triggered, but they are not enough for some misfit task scenarios. Excluding asym packing, those are: - rq->nr_running >=2: Not relevant here because we are running a misfit task, it needs to be migrated regardless and potentially through active balance. - sds->nr_busy_cpus > 1: If there is only the misfit task being run on a group of low capacity CPUs, this will be evaluated to False. - rq->cfs.h_nr_running >=1 && check_cpu_capacity(): Not relevant here, misfit task needs to be migrated regardless of rt/IRQ pressure As such, this commit adds an rq->misfit_task_load condition to trigger a nohz kick. The idea to kick a nohz balance for misfit tasks originally came from Leo Yan <leo.yan@linaro.org>, and a similar patch was submitted for the Android Common Kernel - see: https://lists.linaro.org/pipermail/eas-dev/2016-September/000551.htmlSigned-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-6-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
On asymmetric CPU capacity systems load intensive tasks can end up on CPUs that don't suit their compute demand. In this scenarios 'misfit' tasks should be migrated to CPUs with higher compute capacity to ensure better throughput. group_misfit_task indicates this scenario, but tweaks to the load-balance code are needed to make the migrations happen. Misfit balancing only makes sense between a source group of lower per-CPU capacity and destination group of higher compute capacity. Otherwise, misfit balancing is ignored. group_misfit_task has lowest priority so any imbalance due to overload is dealt with first. The modifications are: 1. Only pick a group containing misfit tasks as the busiest group if the destination group has higher capacity and has spare capacity. 2. When the busiest group is a 'misfit' group, skip the usual average load and group capacity checks. 3. Set the imbalance for 'misfit' balancing sufficiently high for a task to be pulled ignoring average load. 4. Pick the CPU with the highest misfit load as the source CPU. 5. If the misfit task is alone on the source CPU, go for active balancing. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-5-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
The current sg->min_capacity tracks the lowest per-CPU compute capacity available in the sched_group when rt/irq pressure is taken into account. Minimum capacity isn't the ideal metric for tracking if a sched_group needs offloading to another sched_group for some scenarios, e.g. a sched_group with multiple CPUs if only one is under heavy pressure. Tracking maximum capacity isn't perfect either but a better choice for some situations as it indicates that the sched_group definitely compute capacity constrained either due to rt/irq pressure on all CPUs or asymmetric CPU capacities (e.g. big.LITTLE). Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-4-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
To maximize throughput in systems with asymmetric CPU capacities (e.g. ARM big.LITTLE) load-balancing has to consider task and CPU utilization as well as per-CPU compute capacity when load-balancing in addition to the current average load based load-balancing policy. Tasks with high utilization that are scheduled on a lower capacity CPU need to be identified and migrated to a higher capacity CPU if possible to maximize throughput. To implement this additional policy an additional group_type (load-balance scenario) is added: 'group_misfit_task'. This represents scenarios where a sched_group has one or more tasks that are not suitable for its per-CPU capacity. 'group_misfit_task' is only considered if the system is not overloaded or imbalanced ('group_imbalanced' or 'group_overloaded'). Identifying misfit tasks requires the rq lock to be held. To avoid taking remote rq locks to examine source sched_groups for misfit tasks, each CPU is responsible for tracking misfit tasks themselves and update the rq->misfit_task flag. This means checking task utilization when tasks are scheduled and on sched_tick. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-3-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
The existing asymmetric CPU capacity code should cause minimal overhead for others. Putting it behind a static_key, it has been done for SMT optimizations, would make it easier to extend and improve without causing harm to others moving forward. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: gaku.inami.xh@renesas.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1530699470-29808-2-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
Asymmetric CPU capacity can not necessarily be determined accurately at the time the initial sched_domain hierarchy is built during boot. It is therefore necessary to be able to force a full rebuild of the hierarchy later triggered by the arch_topology driver. A full rebuild requires the arch-code to implement arch_update_cpu_topology() which isn't yet implemented for arm. This patch points the arm implementation to arch_topology driver to ensure that full hierarchy rebuild happens when needed. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dietmar.eggemann@arm.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1532093554-30504-5-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
Asymmetric CPU capacity can not necessarily be determined accurately at the time the initial sched_domain hierarchy is built during boot. It is therefore necessary to be able to force a full rebuild of the hierarchy later triggered by the arch_topology driver. A full rebuild requires the arch-code to implement arch_update_cpu_topology() which isn't yet implemented for arm64. This patch points the arm64 implementation to arch_topology driver to ensure that full hierarchy rebuild happens when needed. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: dietmar.eggemann@arm.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1532093554-30504-4-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
sched/topology, drivers/base/arch_topology: Rebuild the sched_domain hierarchy when capacities change The setting of SD_ASYM_CPUCAPACITY depends on the per-CPU capacities. These might not have their final values when the hierarchy is initially built as the values depend on cpufreq to be initialized or the values being set through sysfs. To ensure that the flags are set correctly we need to rebuild the sched_domain hierarchy whenever the reported per-CPU capacity (arch_scale_cpu_capacity()) changes. This patch ensure that a full sched_domain rebuild happens when CPU capacity changes occur. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 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: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1532093554-30504-3-git-send-email-morten.rasmussen@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Morten Rasmussen authored
The SD_ASYM_CPUCAPACITY sched_domain flag is supposed to mark the sched_domain in the hierarchy where all CPU capacities are visible for any CPU's point of view on asymmetric CPU capacity systems. The scheduler can then take to take capacity asymmetry into account when balancing at this level. It also serves as an indicator for how wide task placement heuristics have to search to consider all available CPU capacities as asymmetric systems might often appear symmetric at smallest level(s) of the sched_domain hierarchy. The flag has been around for while but so far only been set by out-of-tree code in Android kernels. One solution is to let each architecture provide the flag through a custom sched_domain topology array and associated mask and flag functions. However, SD_ASYM_CPUCAPACITY is special in the sense that it depends on the capacity and presence of all CPUs in the system, i.e. when hotplugging all CPUs out except those with one particular CPU capacity the flag should disappear even if the sched_domains don't collapse. Similarly, the flag is affected by cpusets where load-balancing is turned off. Detecting when the flags should be set therefore depends not only on topology information but also the cpuset configuration and hotplug state. The arch code doesn't have easy access to the cpuset configuration. Instead, this patch implements the flag detection in generic code where cpusets and hotplug state is already taken care of. All the arch is responsible for is to implement arch_scale_cpu_capacity() and force a full rebuild of the sched_domain hierarchy if capacities are updated, e.g. later in the boot process when cpufreq has initialized. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.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: dietmar.eggemann@arm.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1532093554-30504-2-git-send-email-morten.rasmussen@arm.com [ Fixed 'CPU' capitalization. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Randy Dunlap authored
Fix kernel-doc warning for missing 'flags' parameter description: ../kernel/sched/fair.c:3371: warning: Function parameter or member 'flags' not described in 'attach_entity_load_avg' Signed-off-by: Randy Dunlap <rdunlap@infradead.org> 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> Fixes: ea14b57e ("sched/cpufreq: Provide migration hint") Link: http://lkml.kernel.org/r/cdda0d42-880d-4229-a9f7-5899c977a063@infradead.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Vincent Guittot authored
It can happen that load_balance() finds a busiest group and then a busiest rq but the calculated imbalance is in fact 0. In such situation, detach_tasks() returns immediately and lets the flag LBF_ALL_PINNED set. The busiest CPU is then wrongly assumed to have pinned tasks and removed from the load balance mask. then, we redo a load balance without the busiest CPU. This creates wrong load balance situation and generates wrong task migration. If the calculated imbalance is 0, it's useless to try to find a busiest rq as no task will be migrated and we can return immediately. This situation can happen with heterogeneous system or smp system when RT tasks are decreasing the capacity of some CPUs. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> 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: dietmar.eggemann@arm.com Cc: jhugo@codeaurora.org Link: http://lkml.kernel.org/r/1536306664-29827-1-git-send-email-vincent.guittot@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Vincent Guittot authored
Since commit: 523e979d ("sched/core: Use PELT for scale_rt_capacity()") scale_rt_capacity() returns the remaining capacity and not a scale factor to apply on cpu_capacity_orig. arch_scale_cpu() is directly called by scale_rt_capacity() so we must take the sched_domain argument. Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 523e979d ("sched/core: Use PELT for scale_rt_capacity()") Link: http://lkml.kernel.org/r/20180904093626.GA23936@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Steve Muckle authored
When a task which previously ran on a given CPU is remotely queued to wake up on that same CPU, there is a period where the task's state is TASK_WAKING and its vruntime is not normalized. This is not accounted for in vruntime_normalized() which will cause an error in the task's vruntime if it is switched from the fair class during this time. For example if it is boosted to RT priority via rt_mutex_setprio(), rq->min_vruntime will not be subtracted from the task's vruntime but it will be added again when the task returns to the fair class. The task's vruntime will have been erroneously doubled and the effective priority of the task will be reduced. Note this will also lead to inflation of all vruntimes since the doubled vruntime value will become the rq's min_vruntime when other tasks leave the rq. This leads to repeated doubling of the vruntime and priority penalty. Fix this by recognizing a WAKING task's vruntime as normalized only if sched_remote_wakeup is true. This indicates a migration, in which case the vruntime would have been normalized in migrate_task_rq_fair(). Based on a similar patch from John Dias <joaodias@google.com>. Suggested-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Steve Muckle <smuckle@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Redpath <Chris.Redpath@arm.com> Cc: John Dias <joaodias@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Miguel de Dios <migueldedios@google.com> Cc: Morten Rasmussen <Morten.Rasmussen@arm.com> Cc: Patrick Bellasi <Patrick.Bellasi@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Quentin Perret <quentin.perret@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Todd Kjos <tkjos@google.com> Cc: kernel-team@android.com Fixes: b5179ac7 ("sched/fair: Prepare to fix fairness problems on migration") Link: http://lkml.kernel.org/r/20180831224217.169476-1-smuckle@google.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Vincent Guittot authored
update_blocked_averages() is called to periodiccally decay the stalled load of idle CPUs and to sync all loads before running load balance. When cfs rq is idle, it trigs a load balance during pick_next_task_fair() in order to potentially pull tasks and to use this newly idle CPU. This load balance happens whereas prev task from another class has not been put and its utilization updated yet. This may lead to wrongly account running time as idle time for RT or DL classes. Test that no RT or DL task is running when updating their utilization in update_blocked_averages(). We still update RT and DL utilization instead of simply skipping them to make sure that all metrics are synced when used during load balance. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> 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> Fixes: 371bf427 ("sched/rt: Add rt_rq utilization tracking") Fixes: 3727e0e1 ("sched/dl: Add dl_rq utilization tracking") Link: http://lkml.kernel.org/r/1535728975-22799-1-git-send-email-vincent.guittot@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Srikar Dronamraju authored
With the following commit: 051f3ca0 ("sched/topology: Introduce NUMA identity node sched domain") the scheduler introduced a new NUMA level. However this leads to the NUMA topology on 2 node systems to not be marked as NUMA_DIRECT anymore. After this commit, it gets reported as NUMA_BACKPLANE, because sched_domains_numa_level is now 2 on 2 node systems. Fix this by allowing setting systems that have up to 2 NUMA levels as NUMA_DIRECT. While here remove code that assumes that level can be 0. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andre Wild <wild@linux.vnet.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org> Fixes: 051f3ca0 "Introduce NUMA identity node sched domain" Link: http://lkml.kernel.org/r/1533920419-17410-1-git-send-email-srikar@linux.vnet.ibm.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Jiada Wang authored
The following lockdep report can be triggered by writing to /sys/kernel/debug/sched_features: ====================================================== WARNING: possible circular locking dependency detected 4.18.0-rc6-00152-gcd3f77d7-dirty #18 Not tainted ------------------------------------------------------ sh/3358 is trying to acquire lock: 000000004ad3989d (cpu_hotplug_lock.rw_sem){++++}, at: static_key_enable+0x14/0x30 but task is already holding lock: 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sb->s_type->i_mutex_key#3){+.+.}: lock_acquire+0xb8/0x148 down_write+0xac/0x140 start_creating+0x5c/0x168 debugfs_create_dir+0x18/0x220 opp_debug_register+0x8c/0x120 _add_opp_dev+0x104/0x1f8 dev_pm_opp_get_opp_table+0x174/0x340 _of_add_opp_table_v2+0x110/0x760 dev_pm_opp_of_add_table+0x5c/0x240 dev_pm_opp_of_cpumask_add_table+0x5c/0x100 cpufreq_init+0x160/0x430 cpufreq_online+0x1cc/0xe30 cpufreq_add_dev+0x78/0x198 subsys_interface_register+0x168/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #2 (opp_table_lock){+.+.}: lock_acquire+0xb8/0x148 __mutex_lock+0x104/0xf50 mutex_lock_nested+0x1c/0x28 _of_add_opp_table_v2+0xb4/0x760 dev_pm_opp_of_add_table+0x5c/0x240 dev_pm_opp_of_cpumask_add_table+0x5c/0x100 cpufreq_init+0x160/0x430 cpufreq_online+0x1cc/0xe30 cpufreq_add_dev+0x78/0x198 subsys_interface_register+0x168/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #1 (subsys mutex#6){+.+.}: lock_acquire+0xb8/0x148 __mutex_lock+0x104/0xf50 mutex_lock_nested+0x1c/0x28 subsys_interface_register+0xd8/0x270 cpufreq_register_driver+0x1c8/0x278 dt_cpufreq_probe+0xdc/0x1b8 platform_drv_probe+0xb4/0x168 driver_probe_device+0x318/0x4b0 __device_attach_driver+0xfc/0x1f0 bus_for_each_drv+0xf8/0x180 __device_attach+0x164/0x200 device_initial_probe+0x10/0x18 bus_probe_device+0x110/0x178 device_add+0x6d8/0x908 platform_device_add+0x138/0x3d8 platform_device_register_full+0x1cc/0x1f8 cpufreq_dt_platdev_init+0x174/0x1bc do_one_initcall+0xb8/0x310 kernel_init_freeable+0x4b8/0x56c kernel_init+0x10/0x138 ret_from_fork+0x10/0x18 -> #0 (cpu_hotplug_lock.rw_sem){++++}: __lock_acquire+0x203c/0x21d0 lock_acquire+0xb8/0x148 cpus_read_lock+0x58/0x1c8 static_key_enable+0x14/0x30 sched_feat_write+0x314/0x428 full_proxy_write+0xa0/0x138 __vfs_write+0xd8/0x388 vfs_write+0xdc/0x318 ksys_write+0xb4/0x138 sys_write+0xc/0x18 __sys_trace_return+0x0/0x4 other info that might help us debug this: Chain exists of: cpu_hotplug_lock.rw_sem --> opp_table_lock --> &sb->s_type->i_mutex_key#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#3); lock(opp_table_lock); lock(&sb->s_type->i_mutex_key#3); lock(cpu_hotplug_lock.rw_sem); *** DEADLOCK *** 2 locks held by sh/3358: #0: 00000000a8c4b363 (sb_writers#10){.+.+}, at: vfs_write+0x238/0x318 #1: 00000000c1b31a88 (&sb->s_type->i_mutex_key#3){+.+.}, at: sched_feat_write+0x160/0x428 stack backtrace: CPU: 5 PID: 3358 Comm: sh Not tainted 4.18.0-rc6-00152-gcd3f77d7-dirty #18 Hardware name: Renesas H3ULCB Kingfisher board based on r8a7795 ES2.0+ (DT) Call trace: dump_backtrace+0x0/0x288 show_stack+0x14/0x20 dump_stack+0x13c/0x1ac print_circular_bug.isra.10+0x270/0x438 check_prev_add.constprop.16+0x4dc/0xb98 __lock_acquire+0x203c/0x21d0 lock_acquire+0xb8/0x148 cpus_read_lock+0x58/0x1c8 static_key_enable+0x14/0x30 sched_feat_write+0x314/0x428 full_proxy_write+0xa0/0x138 __vfs_write+0xd8/0x388 vfs_write+0xdc/0x318 ksys_write+0xb4/0x138 sys_write+0xc/0x18 __sys_trace_return+0x0/0x4 This is because when loading the cpufreq_dt module we first acquire cpu_hotplug_lock.rw_sem lock, then in cpufreq_init(), we are taking the &sb->s_type->i_mutex_key lock. But when writing to /sys/kernel/debug/sched_features, the cpu_hotplug_lock.rw_sem lock depends on the &sb->s_type->i_mutex_key lock. To fix this bug, reverse the lock acquisition order when writing to sched_features, this way cpu_hotplug_lock.rw_sem no longer depends on &sb->s_type->i_mutex_key. Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Jiada Wang <jiada_wang@mentor.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Eugeniu Rosca <erosca@de.adit-jv.com> Cc: George G. Davis <george_davis@mentor.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/20180731121222.26195-1-jiada_wang@mentor.comSigned-off-by: Ingo Molnar <mingo@kernel.org>
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Linus Torvalds authored
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- 09 Sep, 2018 7 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fixes from Thomas Gleixner: "A set of fixes for x86: - Prevent multiplication result truncation on 32bit. Introduced with the early timestamp reworrk. - Ensure microcode revision storage to be consistent under all circumstances - Prevent write tearing of PTEs - Prevent confusion of user and kernel reegisters when dumping fatal signals verbosely - Make an error return value in a failure path of the vector allocation negative. Returning EINVAL might the caller assume success and causes further wreckage. - A trivial kernel doc warning fix" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Use WRITE_ONCE() when setting PTEs x86/apic/vector: Make error return value negative x86/process: Don't mix user/kernel regs in 64bit __show_regs() x86/tsc: Prevent result truncation on 32bit x86: Fix kernel-doc atomic.h warnings x86/microcode: Update the new microcode revision unconditionally x86/microcode: Make sure boot_cpu_data.microcode is up-to-date
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull timekeeping fixes from Thomas Gleixner: "Two fixes for timekeeping: - Revert to the previous kthread based update, which is unfortunately required due to lock ordering issues. The removal caused boot failures on old Core2 machines. Add a proper comment why the thread needs to stay to prevent accidental removal in the future. - Fix a silly typo in a function declaration" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: clocksource: Revert "Remove kthread" timekeeping: Fix declaration of read_persistent_wall_and_boot_offset()
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull irqchip fix from Thomas Gleixner: "A single fix to prevent allocating excessive memory in the GIC/ITS driver. While the subject of the patch might suggest otherwise this is a real fix as some SoCs exceed the memory allocation limits and fail to boot" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip/gic-v3-its: Cap lpi_id_bits to reduce memory footprint
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull cpu hotplug fixes from Thomas Gleixner: "Two fixes for the hotplug state machine code: - Move the misplaces smb() in the hotplug thread function to the proper place, otherwise a half update control struct could be observed - Prevent state corruption on error rollback, which causes the state to advance by one and as a consequence skip it in the bringup sequence" * 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu/hotplug: Prevent state corruption on error rollback cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun()
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git://git.kernel.org/pub/scm/linux/kernel/git/tytso/randomLinus Torvalds authored
Pull random driver fix from Ted Ts'o: "Fix things so the choice of whether or not to trust RDRAND to initialize the CRNG is configurable via the boot option random.trust_cpu={on,off}" * tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: random: make CPU trust a boot parameter
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Linus Torvalds authored
Merge tag 'kbuild-fixes-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild fixes from Masahiro Yamada: - make setlocalversion more robust about -dirty check - loosen the pkg-config requirement for Kconfig - change missing depmod to a warning from an error - warn modules_install when System.map is missing * tag 'kbuild-fixes-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kbuild: modules_install: warn when missing System.map file kbuild: make missing $DEPMOD a Warning instead of an Error kconfig: do not require pkg-config on make {menu,n}config kconfig: remove a spurious self-assignment scripts/setlocalversion: git: Make -dirty check more robust
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Randy Dunlap authored
If there is no System.map file for "make modules_install", scripts/depmod.sh will silently exit with success, having done nothing. Since this is an unexpected situation, change it to report a Warning for the missing file. The behavior is not changed except for the Warning message. The (previous) silent success and new Warning can be reproduced by: $ make mrproper; make defconfig $ make modules; make modules_install and since System.map is produced by "make vmlinux", the steps above omit producing the System.map file. Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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- 08 Sep, 2018 6 commits
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git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds authored
Pull KVM fixes from Radim Krčmář: "ARM: - Fix a VFP corruption in 32-bit guest - Add missing cache invalidation for CoW pages - Two small cleanups s390: - Fallout from the hugetlbfs support: pfmf interpretion and locking - VSIE: fix keywrapping for nested guests PPC: - Fix a bug where pages might not get marked dirty, causing guest memory corruption on migration - Fix a bug causing reads from guest memory to use the wrong guest real address for very large HPT guests (>256G of memory), leading to failures in instruction emulation. x86: - Fix out of bound access from malicious pv ipi hypercalls (introduced in rc1) - Fix delivery of pending interrupts when entering a nested guest, preventing arbitrarily late injection - Sanitize kvm_stat output after destroying a guest - Fix infinite loop when emulating a nested guest page fault and improve the surrounding emulation code - Two minor cleanups" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (28 commits) KVM: LAPIC: Fix pv ipis out-of-bounds access KVM: nVMX: Fix loss of pending IRQ/NMI before entering L2 arm64: KVM: Remove pgd_lock KVM: Remove obsolete kvm_unmap_hva notifier backend arm64: KVM: Only force FPEXC32_EL2.EN if trapping FPSIMD KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoW KVM: s390: Properly lock mm context allow_gmap_hpage_1m setting KVM: s390: vsie: copy wrapping keys to right place KVM: s390: Fix pfmf and conditional skey emulation tools/kvm_stat: re-animate display of dead guests tools/kvm_stat: indicate dead guests as such tools/kvm_stat: handle guest removals more gracefully tools/kvm_stat: don't reset stats when setting PID filter for debugfs tools/kvm_stat: fix updates for dead guests tools/kvm_stat: fix handling of invalid paths in debugfs provider tools/kvm_stat: fix python3 issues KVM: x86: Unexport x86_emulate_instruction() KVM: x86: Rename emulate_instruction() to kvm_emulate_instruction() KVM: x86: Do not re-{try,execute} after failed emulation in L2 KVM: x86: Default to not allowing emulation retry in kvm_mmu_page_fault ...
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-socLinus Torvalds authored
Pull ARM SoC fixes from Olof Johansson: "A few more fixes who have trickled in: - MMC bus width fixup for some Allwinner platforms - Fix for NULL deref in ti-aemif when no platform data is passed in - Fix div by 0 in SCMI code - Add a missing module alias in a new RPi driver" * tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: memory: ti-aemif: fix a potential NULL-pointer dereference firmware: arm_scmi: fix divide by zero when sustained_perf_level is zero hwmon: rpi: add module alias to raspberrypi-hwmon arm64: allwinner: dts: h6: fix Pine H64 MMC bus width
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Olof Johansson authored
Merge tag 'sunxi-fixes-for-4.19' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux into fixes Allwinner fixes for 4.19 Just one fix for H6 mmc on the Pine H64: the mmc bus width was missing from the device tree. This was added in 4.19-rc1. * tag 'sunxi-fixes-for-4.19' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux: arm64: allwinner: dts: h6: fix Pine H64 MMC bus width Signed-off-by: Olof Johansson <olof@lixom.net>
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Nadav Amit authored
When page-table entries are set, the compiler might optimize their assignment by using multiple instructions to set the PTE. This might turn into a security hazard if the user somehow manages to use the interim PTE. L1TF does not make our lives easier, making even an interim non-present PTE a security hazard. Using WRITE_ONCE() to set PTEs and friends should prevent this potential security hazard. I skimmed the differences in the binary with and without this patch. The differences are (obviously) greater when CONFIG_PARAVIRT=n as more code optimizations are possible. For better and worse, the impact on the binary with this patch is pretty small. Skimming the code did not cause anything to jump out as a security hazard, but it seems that at least move_soft_dirty_pte() caused set_pte_at() to use multiple writes. Signed-off-by: Nadav Amit <namit@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180902181451.80520-1-namit@vmware.com
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Thomas Gleixner authored
activate_managed() returns EINVAL instead of -EINVAL in case of error. While this is unlikely to happen, the positive return value would cause further malfunction at the call site. Fixes: 2db1f959 ("x86/vector: Handle managed interrupts proper") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linuxLinus Torvalds authored
Pull i2c fixes from Wolfram Sang: - bugfixes for uniphier, i801, and xiic drivers - ID removal (never produced) for imx - one MAINTAINER addition * 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: i2c: xiic: Record xilinx i2c with Zynq fragment i2c: xiic: Make the start and the byte count write atomic i2c: i801: fix DNV's SMBCTRL register offset i2c: imx-lpi2c: Remove mx8dv compatible entry dt-bindings: imx-lpi2c: Remove mx8dv compatible entry i2c: uniphier-f: issue STOP only for last message or I2C_M_STOP i2c: uniphier: issue STOP only for last message or I2C_M_STOP
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- 07 Sep, 2018 2 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arcLinus Torvalds authored
Pull ARC updates from Vineet Gupta: - Fix for atomic_fetch_#op [Will Deacon] - Enable per device IOC [Eugeniy Paltsev] - Remove redundant gcc version checks [Masahiro Yamada] - Miscll platform config/DT updates [Alexey Brodkin] * tag 'arc-4.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: ARC: don't check for HIGHMEM pages in arch_dma_alloc ARC: IOC: panic if both IOC and ZONE_HIGHMEM enabled ARC: dma [IOC] Enable per device io coherency ARC: dma [IOC]: mark DMA devices connected as dma-coherent ARC: atomics: unbork atomic_fetch_##op() arc: remove redundant GCC version checks ARC: sort Kconfig ARC: cleanup show_faulting_vma() ARC: [plat-axs*]: Enable SWAP ARC: [plat-axs*/plat-hsdk]: Allow U-Boot to pass MAC-address to the kernel ARC: configs: cleanup
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David Howells authored
Fix the cell specification mechanism to allow cells to be pre-created without having to specify at least one address (the addresses will be upcalled for). This allows the cell information preload service to avoid the need to issue loads of DNS lookups during boot to get the addresses for each cell (500+ lookups for the 'standard' cell list[*]). The lookups can be done later as each cell is accessed through the filesystem. Also remove the print statement that prints a line every time a new cell is added. [*] There are 144 cells in the list. Each cell is first looked up for an SRV record, and if that fails, for an AFSDB record. These get a list of server names, each of which then has to be looked up to get the addresses for that server. E.g.: dig srv _afs3-vlserver._udp.grand.central.org Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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