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2022-02-16sched/isolation: Use single feature type while referring to housekeeping cpumaskFrederic Weisbecker4-25/+37
Refer to housekeeping APIs using single feature types instead of flags. This prevents from passing multiple isolation features at once to housekeeping interfaces, which soon won't be possible anymore as each isolation features will have their own cpumask. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Reviewed-by: Phil Auld <pauld@redhat.com> Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
2022-02-16psi: fix possible trigger missing in the windowZhaoyang Huang1-16/+30
When a new threshold breaching stall happens after a psi event was generated and within the window duration, the new event is not generated because the events are rate-limited to one per window. If after that no new stall is recorded then the event will not be generated even after rate-limiting duration has passed. This is happening because with no new stall, window_update will not be called even though threshold was previously breached. To fix this, record threshold breaching occurrence and generate the event once window duration is passed. Suggested-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Suren Baghdasaryan <surenb@google.com> Link: https://lore.kernel.org/r/1643093818-19835-1-git-send-email-huangzhaoyang@gmail.com
2022-02-16sched/numa: Avoid migrating task to CPU-less nodeHuang Ying1-5/+20
In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA nodes. But if the number of the hint page faults on a PMEM node is the max for a task, The current NUMA balancing policy may try to place the task on the PMEM node instead of DRAM node. This is unreasonable, because there's no CPU in PMEM NUMA nodes. To fix this, CPU-less nodes are ignored when searching the migration target node for a task in this patch. To test the patch, we run a workload that accesses more memory in PMEM node than memory in DRAM node. Without the patch, the PMEM node will be chosen as preferred node in task_numa_placement(). While the DRAM node will be chosen instead with the patch. Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220214121553.582248-2-ying.huang@intel.com
2022-02-16sched/numa: Fix NUMA topology for systems with CPU-less nodesHuang Ying4-95/+137
The NUMA topology parameters (sched_numa_topology_type, sched_domains_numa_levels, and sched_max_numa_distance, etc.) identified by scheduler may be wrong for systems with CPU-less nodes. For example, the ACPI SLIT of a system with CPU-less persistent memory (Intel Optane DCPMM) nodes is as follows, [000h 0000 4] Signature : "SLIT" [System Locality Information Table] [004h 0004 4] Table Length : 0000042C [008h 0008 1] Revision : 01 [009h 0009 1] Checksum : 59 [00Ah 0010 6] Oem ID : "XXXX" [010h 0016 8] Oem Table ID : "XXXXXXX" [018h 0024 4] Oem Revision : 00000001 [01Ch 0028 4] Asl Compiler ID : "INTL" [020h 0032 4] Asl Compiler Revision : 20091013 [024h 0036 8] Localities : 0000000000000004 [02Ch 0044 4] Locality 0 : 0A 15 11 1C [030h 0048 4] Locality 1 : 15 0A 1C 11 [034h 0052 4] Locality 2 : 11 1C 0A 1C [038h 0056 4] Locality 3 : 1C 11 1C 0A While the `numactl -H` output is as follows, available: 4 nodes (0-3) node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 node 0 size: 64136 MB node 0 free: 5981 MB node 1 cpus: 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 node 1 size: 64466 MB node 1 free: 10415 MB node 2 cpus: node 2 size: 253952 MB node 2 free: 253920 MB node 3 cpus: node 3 size: 253952 MB node 3 free: 253951 MB node distances: node 0 1 2 3 0: 10 21 17 28 1: 21 10 28 17 2: 17 28 10 28 3: 28 17 28 10 In this system, there are only 2 sockets. In each memory controller, both DRAM and PMEM DIMMs are installed. Although the physical NUMA topology is simple, the logical NUMA topology becomes a little complex. Because both the distance(0, 1) and distance (1, 3) are less than the distance (0, 3), it appears that node 1 sits between node 0 and node 3. And the whole system appears to be a glueless mesh NUMA topology type. But it's definitely not, there is even no CPU in node 3. This isn't a practical problem now yet. Because the PMEM nodes (node 2 and node 3 in example system) are offlined by default during system boot. So init_numa_topology_type() called during system boot will ignore them and set sched_numa_topology_type to NUMA_DIRECT. And init_numa_topology_type() is only called at runtime when a CPU of a never-onlined-before node gets plugged in. And there's no CPU in the PMEM nodes. But it appears better to fix this to make the code more robust. To test the potential problem. We have used a debug patch to call init_numa_topology_type() when the PMEM node is onlined (in __set_migration_target_nodes()). With that, the NUMA parameters identified by scheduler is as follows, sched_numa_topology_type: NUMA_GLUELESS_MESH sched_domains_numa_levels: 4 sched_max_numa_distance: 28 To fix the issue, the CPU-less nodes are ignored when the NUMA topology parameters are identified. Because a node may become CPU-less or not at run time because of CPU hotplug, the NUMA topology parameters need to be re-initialized at runtime for CPU hotplug too. With the patch, the NUMA parameters identified for the example system above is as follows, sched_numa_topology_type: NUMA_DIRECT sched_domains_numa_levels: 2 sched_max_numa_distance: 21 Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220214121553.582248-1-ying.huang@intel.com
2022-02-16sched: replace cpumask_weight with cpumask_empty where appropriateYury Norov2-2/+2
In some places, kernel/sched code calls cpumask_weight() to check if any bit of a given cpumask is set. We can do it more efficiently with cpumask_empty() because cpumask_empty() stops traversing the cpumask as soon as it finds first set bit, while cpumask_weight() counts all bits unconditionally. Signed-off-by: Yury Norov <yury.norov@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220210224933.379149-23-yury.norov@gmail.com
2022-02-12sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCsMel Gorman2-10/+65
Commit 7d2b5dd0bcc4 ("sched/numa: Allow a floating imbalance between NUMA nodes") allowed an imbalance between NUMA nodes such that communicating tasks would not be pulled apart by the load balancer. This works fine when there is a 1:1 relationship between LLC and node but can be suboptimal for multiple LLCs if independent tasks prematurely use CPUs sharing cache. Zen* has multiple LLCs per node with local memory channels and due to the allowed imbalance, it's far harder to tune some workloads to run optimally than it is on hardware that has 1 LLC per node. This patch allows an imbalance to exist up to the point where LLCs should be balanced between nodes. On a Zen3 machine running STREAM parallelised with OMP to have on instance per LLC the results and without binding, the results are 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v6 MB/sec copy-16 162596.94 ( 0.00%) 580559.74 ( 257.05%) MB/sec scale-16 136901.28 ( 0.00%) 374450.52 ( 173.52%) MB/sec add-16 157300.70 ( 0.00%) 564113.76 ( 258.62%) MB/sec triad-16 151446.88 ( 0.00%) 564304.24 ( 272.61%) STREAM can use directives to force the spread if the OpenMP is new enough but that doesn't help if an application uses threads and it's not known in advance how many threads will be created. Coremark is a CPU and cache intensive benchmark parallelised with threads. When running with 1 thread per core, the vanilla kernel allows threads to contend on cache. With the patch; 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v5 Min Score-16 368239.36 ( 0.00%) 389816.06 ( 5.86%) Hmean Score-16 388607.33 ( 0.00%) 427877.08 * 10.11%* Max Score-16 408945.69 ( 0.00%) 481022.17 ( 17.62%) Stddev Score-16 15247.04 ( 0.00%) 24966.82 ( -63.75%) CoeffVar Score-16 3.92 ( 0.00%) 5.82 ( -48.48%) It can also make a big difference for semi-realistic workloads like specjbb which can execute arbitrary numbers of threads without advance knowledge of how they should be placed. Even in cases where the average performance is neutral, the results are more stable. 5.17.0-rc0 5.17.0-rc0 vanilla sched-numaimb-v6 Hmean tput-1 71631.55 ( 0.00%) 73065.57 ( 2.00%) Hmean tput-8 582758.78 ( 0.00%) 556777.23 ( -4.46%) Hmean tput-16 1020372.75 ( 0.00%) 1009995.26 ( -1.02%) Hmean tput-24 1416430.67 ( 0.00%) 1398700.11 ( -1.25%) Hmean tput-32 1687702.72 ( 0.00%) 1671357.04 ( -0.97%) Hmean tput-40 1798094.90 ( 0.00%) 2015616.46 * 12.10%* Hmean tput-48 1972731.77 ( 0.00%) 2333233.72 ( 18.27%) Hmean tput-56 2386872.38 ( 0.00%) 2759483.38 ( 15.61%) Hmean tput-64 2909475.33 ( 0.00%) 2925074.69 ( 0.54%) Hmean tput-72 2585071.36 ( 0.00%) 2962443.97 ( 14.60%) Hmean tput-80 2994387.24 ( 0.00%) 3015980.59 ( 0.72%) Hmean tput-88 3061408.57 ( 0.00%) 3010296.16 ( -1.67%) Hmean tput-96 3052394.82 ( 0.00%) 2784743.41 ( -8.77%) Hmean tput-104 2997814.76 ( 0.00%) 2758184.50 ( -7.99%) Hmean tput-112 2955353.29 ( 0.00%) 2859705.09 ( -3.24%) Hmean tput-120 2889770.71 ( 0.00%) 2764478.46 ( -4.34%) Hmean tput-128 2871713.84 ( 0.00%) 2750136.73 ( -4.23%) Stddev tput-1 5325.93 ( 0.00%) 2002.53 ( 62.40%) Stddev tput-8 6630.54 ( 0.00%) 10905.00 ( -64.47%) Stddev tput-16 25608.58 ( 0.00%) 6851.16 ( 73.25%) Stddev tput-24 12117.69 ( 0.00%) 4227.79 ( 65.11%) Stddev tput-32 27577.16 ( 0.00%) 8761.05 ( 68.23%) Stddev tput-40 59505.86 ( 0.00%) 2048.49 ( 96.56%) Stddev tput-48 168330.30 ( 0.00%) 93058.08 ( 44.72%) Stddev tput-56 219540.39 ( 0.00%) 30687.02 ( 86.02%) Stddev tput-64 121750.35 ( 0.00%) 9617.36 ( 92.10%) Stddev tput-72 223387.05 ( 0.00%) 34081.13 ( 84.74%) Stddev tput-80 128198.46 ( 0.00%) 22565.19 ( 82.40%) Stddev tput-88 136665.36 ( 0.00%) 27905.97 ( 79.58%) Stddev tput-96 111925.81 ( 0.00%) 99615.79 ( 11.00%) Stddev tput-104 146455.96 ( 0.00%) 28861.98 ( 80.29%) Stddev tput-112 88740.49 ( 0.00%) 58288.23 ( 34.32%) Stddev tput-120 186384.86 ( 0.00%) 45812.03 ( 75.42%) Stddev tput-128 78761.09 ( 0.00%) 57418.48 ( 27.10%) Similarly, for embarassingly parallel problems like NPB-ep, there are improvements due to better spreading across LLC when the machine is not fully utilised. vanilla sched-numaimb-v6 Min ep.D 31.79 ( 0.00%) 26.11 ( 17.87%) Amean ep.D 31.86 ( 0.00%) 26.17 * 17.86%* Stddev ep.D 0.07 ( 0.00%) 0.05 ( 24.41%) CoeffVar ep.D 0.22 ( 0.00%) 0.20 ( 7.97%) Max ep.D 31.93 ( 0.00%) 26.21 ( 17.91%) Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com> Link: https://lore.kernel.org/r/20220208094334.16379-3-mgorman@techsingularity.net
2022-02-12sched/fair: Improve consistency of allowed NUMA balance calculationsMel Gorman1-8/+10
There are inconsistencies when determining if a NUMA imbalance is allowed that should be corrected. o allow_numa_imbalance changes types and is not always examining the destination group so both the type should be corrected as well as the naming. o find_idlest_group uses the sched_domain's weight instead of the group weight which is different to find_busiest_group o find_busiest_group uses the source group instead of the destination which is different to task_numa_find_cpu o Both find_idlest_group and find_busiest_group should account for the number of running tasks if a move was allowed to be consistent with task_numa_find_cpu Fixes: 7d2b5dd0bcc4 ("sched/numa: Allow a floating imbalance between NUMA nodes") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Link: https://lore.kernel.org/r/20220208094334.16379-2-mgorman@techsingularity.net
2022-02-02sched: move autogroup sysctls into its own fileZhen Ni2-0/+24
move autogroup sysctls to autogroup.c and use the new register_sysctl_init() to register the sysctl interface. Signed-off-by: Zhen Ni <nizhen@uniontech.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220128095025.8745-1-nizhen@uniontech.com
2022-01-27psi: Fix "defined but not used" warnings when CONFIG_PROC_FS=nSuren Baghdasaryan1-38/+41
When CONFIG_PROC_FS is disabled psi code generates the following warnings: kernel/sched/psi.c:1364:30: warning: 'psi_cpu_proc_ops' defined but not used [-Wunused-const-variable=] 1364 | static const struct proc_ops psi_cpu_proc_ops = { | ^~~~~~~~~~~~~~~~ kernel/sched/psi.c:1355:30: warning: 'psi_memory_proc_ops' defined but not used [-Wunused-const-variable=] 1355 | static const struct proc_ops psi_memory_proc_ops = { | ^~~~~~~~~~~~~~~~~~~ kernel/sched/psi.c:1346:30: warning: 'psi_io_proc_ops' defined but not used [-Wunused-const-variable=] 1346 | static const struct proc_ops psi_io_proc_ops = { | ^~~~~~~~~~~~~~~ Make definitions of these structures and related functions conditional on CONFIG_PROC_FS config. Fixes: 0e94682b73bf ("psi: introduce psi monitor") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220119223940.787748-3-surenb@google.com
2022-01-27sched/uclamp: Fix iowait boost escaping uclamp restrictionQais Yousef1-0/+1
iowait_boost signal is applied independently of util and doesn't take into account uclamp settings of the rq. An io heavy task that is capped by uclamp_max could still request higher frequency because sugov_iowait_apply() doesn't clamp the boost via uclamp_rq_util_with() like effective_cpu_util() does. Make sure that iowait_boost honours uclamp requests by calling uclamp_rq_util_with() when applying the boost. Fixes: 982d9cdc22c9 ("sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/20211216225320.2957053-3-qais.yousef@arm.com
2022-01-27sched/sugov: Ignore 'busy' filter when rq is capped by uclamp_maxQais Yousef2-84/+107
sugov_update_single_{freq, perf}() contains a 'busy' filter that ensures we don't bring the frqeuency down if there's no idle time (CPU is busy). The problem is that with uclamp_max we will have scenarios where a busy task is capped to run at a lower frequency and this filter prevents applying the capping when this task starts running. We handle this by skipping the filter when uclamp is enabled and the rq is being capped by uclamp_max. We introduce a new function uclamp_rq_is_capped() to help detecting when this capping is taking effect. Some code shuffling was required to allow using cpu_util_{cfs, rt}() in this new function. On 2 Core SMT2 Intel laptop I see: Without this patch: uclampset -M 0 sysbench --test=cpu --threads = 4 run produces a score of ~3200 consistently. Which is the highest possible. Compiling the kernel also results in frequency running at max 3.1GHz all the time - running uclampset -M 400 to cap it has no effect without this patch. With this patch: uclampset -M 0 sysbench --test=cpu --threads = 4 run produces a score of ~1100 with some outliers in ~1700. Uclamp max aggregates the performance requirements, so having high values sometimes is expected if some other task happens to require that frequency starts running at the same time. When compiling the kernel with uclampset -M 400 I can see the frequencies mostly in the ~2GHz region. Helpful to conserve power and prevent heating when not plugged in. Fixes: 982d9cdc22c9 ("sched/cpufreq, sched/uclamp: Add clamps for FAIR and RT tasks") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211216225320.2957053-2-qais.yousef@arm.com
2022-01-27sched/core: Export pelt_thermal_tpQais Yousef1-0/+1
We can't use this tracepoint in modules without having the symbol exported first, fix that. Fixes: 765047932f15 ("sched/pelt: Add support to track thermal pressure") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211028115005.873539-1-qais.yousef@arm.com
2022-01-27sched/numa: initialize numa statistics when forking new taskHonglei Wang1-0/+2
The child processes will inherit numa_pages_migrated and total_numa_faults from the parent. It means even if there is no numa fault happen on the child, the statistics in /proc/$pid of the child process might show huge amount. This is a bit weird. Let's initialize them when do fork. Signed-off-by: Honglei Wang <wanghonglei@didichuxing.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mel Gorman <mgorman@suse.de> Link: https://lore.kernel.org/r/20220113133920.49900-1-wanghonglei@didichuxing.com
2022-01-27sched/debug: Remove mpol_get/put and task_lock/unlock from sched_show_numaBharata B Rao1-10/+0
The older format of /proc/pid/sched printed home node info which required the mempolicy and task lock around mpol_get(). However the format has changed since then and there is no need for sched_show_numa() any more to have mempolicy argument, asssociated mpol_get/put and task_lock/unlock. Remove them. Fixes: 397f2378f1361 ("sched/numa: Fix numa balancing stats in /proc/pid/sched") Signed-off-by: Bharata B Rao <bharata@amd.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Link: https://lore.kernel.org/r/20220118050515.2973-1-bharata@amd.com
2022-01-17Merge branch 'signal-for-v5.17' of ↵Linus Torvalds1-8/+8
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull signal/exit/ptrace updates from Eric Biederman: "This set of changes deletes some dead code, makes a lot of cleanups which hopefully make the code easier to follow, and fixes bugs found along the way. The end-game which I have not yet reached yet is for fatal signals that generate coredumps to be short-circuit deliverable from complete_signal, for force_siginfo_to_task not to require changing userspace configured signal delivery state, and for the ptrace stops to always happen in locations where we can guarantee on all architectures that the all of the registers are saved and available on the stack. Removal of profile_task_ext, profile_munmap, and profile_handoff_task are the big successes for dead code removal this round. A bunch of small bug fixes are included, as most of the issues reported were small enough that they would not affect bisection so I simply added the fixes and did not fold the fixes into the changes they were fixing. There was a bug that broke coredumps piped to systemd-coredump. I dropped the change that caused that bug and replaced it entirely with something much more restrained. Unfortunately that required some rebasing. Some successes after this set of changes: There are few enough calls to do_exit to audit in a reasonable amount of time. The lifetime of struct kthread now matches the lifetime of struct task, and the pointer to struct kthread is no longer stored in set_child_tid. The flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is removed. Issues where task->exit_code was examined with signal->group_exit_code should been examined were fixed. There are several loosely related changes included because I am cleaning up and if I don't include them they will probably get lost. The original postings of these changes can be found at: https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org I trimmed back the last set of changes to only the obviously correct once. Simply because there was less time for review than I had hoped" * 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits) ptrace/m68k: Stop open coding ptrace_report_syscall ptrace: Remove unused regs argument from ptrace_report_syscall ptrace: Remove second setting of PT_SEIZED in ptrace_attach taskstats: Cleanup the use of task->exit_code exit: Use the correct exit_code in /proc/<pid>/stat exit: Fix the exit_code for wait_task_zombie exit: Coredumps reach do_group_exit exit: Remove profile_handoff_task exit: Remove profile_task_exit & profile_munmap signal: clean up kernel-doc comments signal: Remove the helper signal_group_exit signal: Rename group_exit_task group_exec_task coredump: Stop setting signal->group_exit_task signal: Remove SIGNAL_GROUP_COREDUMP signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process signal: Make coredump handling explicit in complete_signal signal: Have prepare_signal detect coredumps using signal->core_state signal: Have the oom killer detect coredumps using signal->core_state exit: Move force_uaccess back into do_exit exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit ...
2022-01-12Merge tag 'locking_core_for_v5.17_rc1' of ↵Linus Torvalds1-0/+3
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Borislav Petkov: "Lots of cleanups and preparation. Highlights: - futex: Cleanup and remove runtime futex_cmpxchg detection - rtmutex: Some fixes for the PREEMPT_RT locking infrastructure - kcsan: Share owner_on_cpu() between mutex,rtmutex and rwsem and annotate the racy owner->on_cpu access *once*. - atomic64: Dead-Code-Elemination" [ Description above by Peter Zijlstra ] * tag 'locking_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/atomic: atomic64: Remove unusable atomic ops futex: Fix additional regressions locking: Allow to include asm/spinlock_types.h from linux/spinlock_types_raw.h x86/mm: Include spinlock_t definition in pgtable. locking: Mark racy reads of owner->on_cpu locking: Make owner_on_cpu() into <linux/sched.h> lockdep/selftests: Adapt ww-tests for PREEMPT_RT lockdep/selftests: Skip the softirq related tests on PREEMPT_RT lockdep/selftests: Unbalanced migrate_disable() & rcu_read_lock(). lockdep/selftests: Avoid using local_lock_{acquire|release}(). lockdep: Remove softirq accounting on PREEMPT_RT. locking/rtmutex: Add rt_mutex_lock_nest_lock() and rt_mutex_lock_killable(). locking/rtmutex: Squash self-deadlock check for ww_rt_mutex. locking: Remove rt_rwlock_is_contended(). sched: Trigger warning if ->migration_disabled counter underflows. futex: Fix sparc32/m68k/nds32 build regression futex: Remove futex_cmpxchg detection futex: Ensure futex_atomic_cmpxchg_inatomic() is present kernel/locking: Use a pointer in ww_mutex_trylock().
2022-01-12Merge tag 'sched_core_for_v5.17_rc1' of ↵Linus Torvalds11-180/+325
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Borislav Petkov: "Mostly minor things this time; some highlights: - core-sched: Add 'Forced Idle' accounting; this allows to track how much CPU time is 'lost' due to core scheduling constraints. - psi: Fix for MEM_FULL; a task running reclaim would be counted as a runnable task and prevent MEM_FULL from being reported. - cpuacct: Long standing fixes for some cgroup accounting issues. - rt: Bandwidth timer could, under unusual circumstances, be failed to armed, leading to indefinite throttling." [ Description above by Peter Zijlstra ] * tag 'sched_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Replace CFS internal cpu_util() with cpu_util_cfs() sched/fair: Cleanup task_util and capacity type sched/rt: Try to restart rt period timer when rt runtime exceeded sched/fair: Document the slow path and fast path in select_task_rq_fair sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacity sched/fair: Fix detection of per-CPU kthreads waking a task sched/cpuacct: Make user/system times in cpuacct.stat more precise sched/cpuacct: Fix user/system in shown cpuacct.usage* cpuacct: Convert BUG_ON() to WARN_ON_ONCE() cputime, cpuacct: Include guest time in user time in cpuacct.stat psi: Fix PSI_MEM_FULL state when tasks are in memstall and doing reclaim sched/core: Forced idle accounting psi: Add a missing SPDX license header psi: Remove repeated verbose comment
2022-01-11Merge tag 'kcsan.2022.01.09a' of ↵Linus Torvalds1-4/+3
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull KCSAN updates from Paul McKenney: "This provides KCSAN fixes and also the ability to take memory barriers into account for weakly-ordered systems. This last can increase the probability of detecting certain types of data races" * tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits) kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it kcsan: Avoid nested contexts reading inconsistent reorder_access kcsan: Turn barrier instrumentation into macros kcsan: Make barrier tests compatible with lockdep kcsan: Support WEAK_MEMORY with Clang where no objtool support exists compiler_attributes.h: Add __disable_sanitizer_instrumentation objtool, kcsan: Remove memory barrier instrumentation from noinstr objtool, kcsan: Add memory barrier instrumentation to whitelist sched, kcsan: Enable memory barrier instrumentation mm, kcsan: Enable barrier instrumentation x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock() x86/barriers, kcsan: Use generic instrumentation for non-smp barriers asm-generic/bitops, kcsan: Add instrumentation for barriers locking/atomics, kcsan: Add instrumentation for barriers locking/barriers, kcsan: Support generic instrumentation locking/barriers, kcsan: Add instrumentation for barriers kcsan: selftest: Add test case to check memory barrier instrumentation kcsan: Ignore GCC 11+ warnings about TSan runtime support kcsan: test: Add test cases for memory barrier instrumentation kcsan: test: Match reordered or normal accesses ...
2022-01-10Merge tag 'core_entry_for_v5.17_rc1' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull thread_info flag accessor helper updates from Borislav Petkov: "Add a set of thread_info.flags accessors which snapshot it before accesing it in order to prevent any potential data races, and convert all users to those new accessors" * tag 'core_entry_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: powerpc: Snapshot thread flags powerpc: Avoid discarding flags in system_call_exception() openrisc: Snapshot thread flags microblaze: Snapshot thread flags arm64: Snapshot thread flags ARM: Snapshot thread flags alpha: Snapshot thread flags sched: Snapshot thread flags entry: Snapshot thread flags x86: Snapshot thread flags thread_info: Add helpers to snapshot thread flags
2022-01-08kthread: Generalize pf_io_worker so it can point to struct kthreadEric W. Biederman1-1/+1
The point of using set_child_tid to hold the kthread pointer was that it already did what is necessary. There are now restrictions on when set_child_tid can be initialized and when set_child_tid can be used in schedule_tail. Which indicates that continuing to use set_child_tid to hold the kthread pointer is a bad idea. Instead of continuing to use the set_child_tid field of task_struct generalize the pf_io_worker field of task_struct and use it to hold the kthread pointer. Rename pf_io_worker (which is a void * pointer) to worker_private so it can be used to store kthreads struct kthread pointer. Update the kthread code to store the kthread pointer in the worker_private field. Remove the places where set_child_tid had to be dealt with carefully because kthreads also used it. Link: https://lkml.kernel.org/r/CAHk-=wgtFAA9SbVYg0gR1tqPMC17-NYcs0GQkaYg1bGhh1uJQQ@mail.gmail.com Link: https://lkml.kernel.org/r/87a6grvqy8.fsf_-_@email.froward.int.ebiederm.org Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-23kthread: Never put_user the set_child_tid addressEric W. Biederman1-1/+1
Kernel threads abuse set_child_tid. Historically that has been fine as set_child_tid was initialized after the kernel thread had been forked. Unfortunately storing struct kthread in set_child_tid after the thread is running makes struct kthread being unusable for storing result codes of the thread. When set_child_tid is set to struct kthread during fork that results in schedule_tail writing the thread id to the beggining of struct kthread (if put_user does not realize it is a kernel address). Solve this by skipping the put_user for all kthreads. Reported-by: Nathan Chancellor <nathan@kernel.org> Link: https://lkml.kernel.org/r/YcNsG0Lp94V13whH@archlinux-ax161 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-22kthread: Warn about failed allocations for the init kthreadEric W. Biederman1-1/+1
Failed allocates are not expected when setting up the initial task and it is not really possible to handle them either. So I added a warning to report if such an allocation failure ever happens. Correct the sense of the warning so it warns when an allocation failure happens not when the allocation succeeded. Oops. Reported-by: kernel test robot <oliver.sang@intel.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Link: https://lkml.kernel.org/r/20211221231611.785b74cf@canb.auug.org.au Link: https://lkml.kernel.org/r/CA+G9fYvLaR5CF777CKeWTO+qJFTN6vAvm95gtzN+7fw3Wi5hkA@mail.gmail.com Link: https://lkml.kernel.org/r/20211216102956.GC10708@xsang-OptiPlex-9020 Fixes: 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13kthread: Ensure struct kthread is present for all kthreadsEric W. Biederman1-8/+8
Today the rules are a bit iffy and arbitrary about which kernel threads have struct kthread present. Both idle threads and thread started with create_kthread want struct kthread present so that is effectively all kernel threads. Make the rule that if PF_KTHREAD and the task is running then struct kthread is present. This will allow the kernel thread code to using tsk->exit_code with different semantics from ordinary processes. To make ensure that struct kthread is present for all kernel threads move it's allocation into copy_process. Add a deallocation of struct kthread in exec for processes that were kernel threads. Move the allocation of struct kthread for the initial thread earlier so that it is not repeated for each additional idle thread. Move the initialization of struct kthread into set_kthread_struct so that the structure is always and reliably initailized. Clear set_child_tid in free_kthread_struct to ensure the kthread struct is reliably freed during exec. The function free_kthread_struct does not need to clear vfork_done during exec as exec_mm_release called from exec_mmap has already cleared vfork_done. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13Merge tag 'v5.16-rc5' into locking/core, to pick up fixesIngo Molnar3-10/+19
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-12-11sched/fair: Replace CFS internal cpu_util() with cpu_util_cfs()Dietmar Eggemann4-69/+50
cpu_util_cfs() was created by commit d4edd662ac16 ("sched/cpufreq: Use the DEADLINE utilization signal") to enable the access to CPU utilization from the Schedutil CPUfreq governor. Commit a07630b8b2c1 ("sched/cpufreq/schedutil: Use util_est for OPP selection") added util_est support later. The only thing cpu_util() is doing on top of what cpu_util_cfs() already does is to clamp the return value to the [0..capacity_orig] capacity range of the CPU. Integrating this into cpu_util_cfs() is not harming the existing users (Schedutil and CPUfreq cooling (latter via sched_cpu_util() wrapper)). For straightforwardness, prefer to keep using `int cpu` as the function parameter over using `struct rq *rq` which might avoid some calls to cpu_rq(cpu) -> per_cpu(runqueues, cpu) -> RELOC_HIDE(). Update cfs_util()'s documentation and reuse it for cpu_util_cfs(). Remove cpu_util(). Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lore.kernel.org/r/20211118164240.623551-1-dietmar.eggemann@arm.com
2021-12-10sched, kcsan: Enable memory barrier instrumentationMarco Elver1-4/+3
There's no fundamental reason to disable KCSAN for scheduler code, except for excessive noise and performance concerns (instrumenting scheduler code is usually a good way to stress test KCSAN itself). However, several core sched functions imply memory barriers that are invisible to KCSAN without instrumentation, but are required to avoid false positives. Therefore, unconditionally enable instrumentation of memory barriers in scheduler code. Also update the comment to reflect this and be a bit more brief. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09wait: add wake_up_pollfree()Eric Biggers1-0/+7
Several ->poll() implementations are special in that they use a waitqueue whose lifetime is the current task, rather than the struct file as is normally the case. This is okay for blocking polls, since a blocking poll occurs within one task; however, non-blocking polls require another solution. This solution is for the queue to be cleared before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'. However, that has a bug: wake_up_poll() calls __wake_up() with nr_exclusive=1. Therefore, if there are multiple "exclusive" waiters, and the wakeup function for the first one returns a positive value, only that one will be called. That's *not* what's needed for POLLFREE; POLLFREE is special in that it really needs to wake up everyone. Considering the three non-blocking poll systems: - io_uring poll doesn't handle POLLFREE at all, so it is broken anyway. - aio poll is unaffected, since it doesn't support exclusive waits. However, that's fragile, as someone could add this feature later. - epoll doesn't appear to be broken by this, since its wakeup function returns 0 when it sees POLLFREE. But this is fragile. Although there is a workaround (see epoll), it's better to define a function which always sends POLLFREE to all waiters. Add such a function. Also make it verify that the queue really becomes empty after all waiters have been woken up. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
2021-12-09sched/fair: Cleanup task_util and capacity typeVincent Donnefort1-2/+3
task_util and capacity are comparable unsigned long values. There is no need for an intermidiate implicit signed cast. Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211207095755.859972-1-vincent.donnefort@arm.com
2021-12-07sched/rt: Try to restart rt period timer when rt runtime exceededLi Hua1-5/+18
When rt_runtime is modified from -1 to a valid control value, it may cause the task to be throttled all the time. Operations like the following will trigger the bug. E.g: 1. echo -1 > /proc/sys/kernel/sched_rt_runtime_us 2. Run a FIFO task named A that executes while(1) 3. echo 950000 > /proc/sys/kernel/sched_rt_runtime_us When rt_runtime is -1, The rt period timer will not be activated when task A enqueued. And then the task will be throttled after setting rt_runtime to 950,000. The task will always be throttled because the rt period timer is not activated. Fixes: d0b27fa77854 ("sched: rt-group: synchonised bandwidth period") Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Li Hua <hucool.lihua@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211203033618.11895-1-hucool.lihua@huawei.com
2021-12-07sched/fair: Document the slow path and fast path in select_task_rq_fairBarry Song1-0/+5
All People I know including myself took a long time to figure out that typical wakeup will always go to fast path and never go to slow path except WF_FORK and WF_EXEC. Vincent reminded me once in a linaro meeting and made me understand slow path won't happen for WF_TTWU. But my other friends repeatedly wasted a lot of time on testing this path like me before I reminded them. So obviously the code needs some document. Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211016111109.5559-1-21cnbao@gmail.com
2021-12-04sched: Trigger warning if ->migration_disabled counter underflows.Sebastian Andrzej Siewior1-0/+3
If migrate_enable() is used more often than its counter part then it remains undetected and rq::nr_pinned will underflow, too. Add a warning if migrate_enable() is attempted if without a matching a migrate_disable(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20211129174654.668506-2-bigeasy@linutronix.de
2021-12-04sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacityVincent Donnefort1-1/+2
select_idle_sibling() has a special case for tasks woken up by a per-CPU kthread where the selected CPU is the previous one. For asymmetric CPU capacity systems, the assumption was that the wakee couldn't have a bigger utilization during task placement than it used to have during the last activation. That was not considering uclamp.min which can completely change between two task activations and as a consequence mandates the fitness criterion asym_fits_capacity(), even for the exit path described above. Fixes: b4c9c9f15649 ("sched/fair: Prefer prev cpu in asymmetric wakeup path") Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/20211129173115.4006346-1-vincent.donnefort@arm.com
2021-12-04sched/fair: Fix detection of per-CPU kthreads waking a taskVincent Donnefort1-0/+1
select_idle_sibling() has a special case for tasks woken up by a per-CPU kthread, where the selected CPU is the previous one. However, the current condition for this exit path is incomplete. A task can wake up from an interrupt context (e.g. hrtimer), while a per-CPU kthread is running. A such scenario would spuriously trigger the special case described above. Also, a recent change made the idle task like a regular per-CPU kthread, hence making that situation more likely to happen (is_per_cpu_kthread(swapper) being true now). Checking for task context makes sure select_idle_sibling() will not interpret a wake up from any other context as a wake up by a per-CPU kthread. Fixes: 52262ee567ad ("sched/fair: Allow a per-CPU kthread waking a task to stack on the same CPU, to fix XFS performance regression") Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lore.kernel.org/r/20211201143450.479472-1-vincent.donnefort@arm.com
2021-12-04sched/uclamp: Fix rq->uclamp_max not set on first enqueueQais Yousef1-1/+1
Commit d81ae8aac85c ("sched/uclamp: Fix initialization of struct uclamp_rq") introduced a bug where uclamp_max of the rq is not reset to match the woken up task's uclamp_max when the rq is idle. The code was relying on rq->uclamp_max initialized to zero, so on first enqueue static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p, enum uclamp_id clamp_id) { ... if (uc_se->value > READ_ONCE(uc_rq->value)) WRITE_ONCE(uc_rq->value, uc_se->value); } was actually resetting it. But since commit d81ae8aac85c changed the default to 1024, this no longer works. And since rq->uclamp_flags is also initialized to 0, neither above code path nor uclamp_idle_reset() update the rq->uclamp_max on first wake up from idle. This is only visible from first wake up(s) until the first dequeue to idle after enabling the static key. And it only matters if the uclamp_max of this task is < 1024 since only then its uclamp_max will be effectively ignored. Fix it by properly initializing rq->uclamp_flags = UCLAMP_FLAG_IDLE to ensure uclamp_idle_reset() is called which then will update the rq uclamp_max value as expected. Fixes: d81ae8aac85c ("sched/uclamp: Fix initialization of struct uclamp_rq") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/20211202112033.1705279-1-qais.yousef@arm.com
2021-12-04preempt/dynamic: Fix setup_preempt_mode() return valueAndrew Halaney1-2/+2
__setup() callbacks expect 1 for success and 0 for failure. Correct the usage here to reflect that. Fixes: 826bfeb37bb4 ("preempt/dynamic: Support dynamic preempt with preempt= boot option") Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Halaney <ahalaney@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211203233203.133581-1-ahalaney@redhat.com
2021-12-02sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_fullFrederic Weisbecker1-3/+9
getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime than the actual time. task_cputime_adjusted() snapshots utime and stime and then adjust their sum to match the scheduler maintained cputime.sum_exec_runtime. Unfortunately in nohz_full, sum_exec_runtime is only updated once per second in the worst case, causing a discrepancy against utime and stime that can be updated anytime by the reader using vtime. To fix this situation, perform an update of cputime.sum_exec_runtime when the cputime snapshot reports the task as actually running while the tick is disabled. The related overhead is then contained within the relevant situations. Reported-by: Hasegawa Hitomi <hasegawa-hitomi@fujitsu.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Hasegawa Hitomi <hasegawa-hitomi@fujitsu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com> Acked-by: Phil Auld <pauld@redhat.com> Link: https://lore.kernel.org/r/20211026141055.57358-3-frederic@kernel.org
2021-12-01sched: Snapshot thread flagsMark Rutland1-1/+1
Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. The READ_ONCE(ti->flags) .. cmpxchg(ti->flags) loop in set_nr_if_polling() is left as-is for clarity. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Paul E. McKenney <paulmck@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lore.kernel.org/r/20211129130653.2037928-4-mark.rutland@arm.com
2021-11-24sched/scs: Reset task stack state in bringup_cpu()Mark Rutland1-4/+0
To hot unplug a CPU, the idle task on that CPU calls a few layers of C code before finally leaving the kernel. When KASAN is in use, poisoned shadow is left around for each of the active stack frames, and when shadow call stacks are in use. When shadow call stacks (SCS) are in use the task's saved SCS SP is left pointing at an arbitrary point within the task's shadow call stack. When a CPU is offlined than onlined back into the kernel, this stale state can adversely affect execution. Stale KASAN shadow can alias new stackframes and result in bogus KASAN warnings. A stale SCS SP is effectively a memory leak, and prevents a portion of the shadow call stack being used. Across a number of hotplug cycles the idle task's entire shadow call stack can become unusable. We previously fixed the KASAN issue in commit: e1b77c92981a5222 ("sched/kasan: remove stale KASAN poison after hotplug") ... by removing any stale KASAN stack poison immediately prior to onlining a CPU. Subsequently in commit: f1a0a376ca0c4ef1 ("sched/core: Initialize the idle task with preemption disabled") ... the refactoring left the KASAN and SCS cleanup in one-time idle thread initialization code rather than something invoked prior to each CPU being onlined, breaking both as above. We fixed SCS (but not KASAN) in commit: 63acd42c0d4942f7 ("sched/scs: Reset the shadow stack when idle_task_exit") ... but as this runs in the context of the idle task being offlined it's potentially fragile. To fix these consistently and more robustly, reset the SCS SP and KASAN shadow of a CPU's idle task immediately before we online that CPU in bringup_cpu(). This ensures the idle task always has a consistent state when it is running, and removes the need to so so when exiting an idle task. Whenever any thread is created, dup_task_struct() will give the task a stack which is free of KASAN shadow, and initialize the task's SCS SP, so there's no need to specially initialize either for idle thread within init_idle(), as this was only necessary to handle hotplug cycles. I've tested this on arm64 with: * gcc 11.1.0, defconfig +KASAN_INLINE, KASAN_STACK * clang 12.0.0, defconfig +KASAN_INLINE, KASAN_STACK, SHADOW_CALL_STACK ... offlining and onlining CPUS with: | while true; do | for C in /sys/devices/system/cpu/cpu*/online; do | echo 0 > $C; | echo 1 > $C; | done | done Fixes: f1a0a376ca0c4ef1 ("sched/core: Initialize the idle task with preemption disabled") Reported-by: Qian Cai <quic_qiancai@quicinc.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Tested-by: Qian Cai <quic_qiancai@quicinc.com> Link: https://lore.kernel.org/lkml/20211115113310.35693-1-mark.rutland@arm.com/
2021-11-23sched/cpuacct: Make user/system times in cpuacct.stat more preciseAndrey Ryabinin1-10/+15
cpuacct.stat shows user time based on raw random precision tick based counters. Use cputime_addjust() to scale these values against the total runtime accounted by the scheduler, like we already do for user/system times in /proc/<pid>/stat. Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20211115164607.23784-4-arbn@yandex-team.com
2021-11-23sched/cpuacct: Fix user/system in shown cpuacct.usage*Andrey Ryabinin1-47/+32
cpuacct has 2 different ways of accounting and showing user and system times. The first one uses cpuacct_account_field() to account times and cpuacct.stat file to expose them. And this one seems to work ok. The second one is uses cpuacct_charge() function for accounting and set of cpuacct.usage* files to show times. Despite some attempts to fix it in the past it still doesn't work. Sometimes while running KVM guest the cpuacct_charge() accounts most of the guest time as system time. This doesn't match with user&system times shown in cpuacct.stat or proc/<pid>/stat. Demonstration: # git clone https://github.com/aryabinin/kvmsample # make # mkdir /sys/fs/cgroup/cpuacct/test # echo $$ > /sys/fs/cgroup/cpuacct/test/tasks # ./kvmsample & # for i in {1..5}; do cat /sys/fs/cgroup/cpuacct/test/cpuacct.usage_sys; sleep 1; done 1976535645 2979839428 3979832704 4983603153 5983604157 Use cpustats accounted in cpuacct_account_field() as the source of user/sys times for cpuacct.usage* files. Make cpuacct_charge() to account only summary execution time. Fixes: d740037fac70 ("sched/cpuacct: Split usage accounting into user_usage and sys_usage") Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20211115164607.23784-3-arbn@yandex-team.com
2021-11-23cpuacct: Convert BUG_ON() to WARN_ON_ONCE()Andrey Ryabinin1-1/+2
Replace fatal BUG_ON() with more safe WARN_ON_ONCE() in cpuacct_cpuusage_read(). Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20211115164607.23784-2-arbn@yandex-team.com
2021-11-23cputime, cpuacct: Include guest time in user time in cpuacct.statAndrey Ryabinin1-2/+2
cpuacct.stat in no-root cgroups shows user time without guest time included int it. This doesn't match with user time shown in root cpuacct.stat and /proc/<pid>/stat. This also affects cgroup2's cpu.stat in the same way. Make account_guest_time() to add user time to cgroup's cpustat to fix this. Fixes: ef12fefabf94 ("cpuacct: add per-cgroup utime/stime statistics") Signed-off-by: Andrey Ryabinin <arbn@yandex-team.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20211115164607.23784-1-arbn@yandex-team.com
2021-11-17psi: Fix PSI_MEM_FULL state when tasks are in memstall and doing reclaimBrian Chen2-18/+32
We've noticed cases where tasks in a cgroup are stalled on memory but there is little memory FULL pressure since tasks stay on the runqueue in reclaim. A simple example involves a single threaded program that keeps leaking and touching large amounts of memory. It runs in a cgroup with swap enabled, memory.high set at 10M and cpu.max ratio set at 5%. Though there is significant CPU pressure and memory SOME, there is barely any memory FULL since the task enters reclaim and stays on the runqueue. However, this memory-bound task is effectively stalled on memory and we expect memory FULL to match memory SOME in this scenario. The code is confused about memstall && running, thinking there is a stalled task and a productive task when there's only one task: a reclaimer that's counted as both. To fix this, we redefine the condition for PSI_MEM_FULL to check that all running tasks are in an active memstall instead of checking that there are no running tasks. case PSI_MEM_FULL: - return unlikely(tasks[NR_MEMSTALL] && !tasks[NR_RUNNING]); + return unlikely(tasks[NR_MEMSTALL] && + tasks[NR_RUNNING] == tasks[NR_MEMSTALL_RUNNING]); This will capture reclaimers. It will also capture tasks that called psi_memstall_enter() and are about to sleep, but this should be negligible noise. Signed-off-by: Brian Chen <brianchen118@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: https://lore.kernel.org/r/20211110213312.310243-1-brianchen118@gmail.com
2021-11-17sched/core: Forced idle accountingJosh Don5-24/+162
Adds accounting for "forced idle" time, which is time where a cookie'd task forces its SMT sibling to idle, despite the presence of runnable tasks. Forced idle time is one means to measure the cost of enabling core scheduling (ie. the capacity lost due to the need to force idle). Forced idle time is attributed to the thread responsible for causing the forced idle. A few details: - Forced idle time is displayed via /proc/PID/sched. It also requires that schedstats is enabled. - Forced idle is only accounted when a sibling hyperthread is held idle despite the presence of runnable tasks. No time is charged if a sibling is idle but has no runnable tasks. - Tasks with 0 cookie are never charged forced idle. - For SMT > 2, we scale the amount of forced idle charged based on the number of forced idle siblings. Additionally, we split the time up and evenly charge it to all running tasks, as each is equally responsible for the forced idle. Signed-off-by: Josh Don <joshdon@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211018203428.2025792-1-joshdon@google.com
2021-11-17psi: Add a missing SPDX license headerLiu Xinpeng1-0/+1
Add the missing SPDX license header to include/linux/psi.h include/linux/psi_types.h kernel/sched/psi.c Signed-off-by: Liu Xinpeng <liuxp11@chinatelecom.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: https://lore.kernel.org/r/1635133586-84611-2-git-send-email-liuxp11@chinatelecom.cn
2021-11-17psi: Remove repeated verbose commentLiu Xinpeng1-1/+0
Comment in function psi_task_switch,there are two same lines. ... * runtime state, the cgroup that contains both tasks * runtime state, the cgroup that contains both tasks ... Signed-off-by: Liu Xinpeng <liuxp11@chinatelecom.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: https://lore.kernel.org/r/1635133586-84611-1-git-send-email-liuxp11@chinatelecom.cn
2021-11-11preempt: Restore preemption model selection configsValentin Schneider1-3/+3
Commit c597bfddc9e9 ("sched: Provide Kconfig support for default dynamic preempt mode") changed the selectable config names for the preemption model. This means a config file must now select CONFIG_PREEMPT_BEHAVIOUR=y rather than CONFIG_PREEMPT=y to get a preemptible kernel. This means all arch config files would need to be updated - right now they'll all end up with the default CONFIG_PREEMPT_NONE_BEHAVIOUR. Rather than touch a good hundred of config files, restore usage of CONFIG_PREEMPT{_NONE, _VOLUNTARY}. Make them configure: o The build-time preemption model when !PREEMPT_DYNAMIC o The default boot-time preemption model when PREEMPT_DYNAMIC Add siblings of those configs with the _BUILD suffix to unconditionally designate the build-time preemption model (PREEMPT_DYNAMIC is built with the "highest" preemption model it supports, aka PREEMPT). Downstream configs should by now all be depending / selected by CONFIG_PREEMPTION rather than CONFIG_PREEMPT, so only a few sites need patching up. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20211110202448.4054153-2-valentin.schneider@arm.com
2021-11-11sched/fair: Prevent dead task groups from regaining cfs_rq'sMathias Krause5-16/+49
Kevin is reporting crashes which point to a use-after-free of a cfs_rq in update_blocked_averages(). Initial debugging revealed that we've live cfs_rq's (on_list=1) in an about to be kfree()'d task group in free_fair_sched_group(). However, it was unclear how that can happen. His kernel config happened to lead to a layout of struct sched_entity that put the 'my_q' member directly into the middle of the object which makes it incidentally overlap with SLUB's freelist pointer. That, in combination with SLAB_FREELIST_HARDENED's freelist pointer mangling, leads to a reliable access violation in form of a #GP which made the UAF fail fast. Michal seems to have run into the same issue[1]. He already correctly diagnosed that commit a7b359fc6a37 ("sched/fair: Correctly insert cfs_rq's to list on unthrottle") is causing the preconditions for the UAF to happen by re-adding cfs_rq's also to task groups that have no more running tasks, i.e. also to dead ones. His analysis, however, misses the real root cause and it cannot be seen from the crash backtrace only, as the real offender is tg_unthrottle_up() getting called via sched_cfs_period_timer() via the timer interrupt at an inconvenient time. When unregister_fair_sched_group() unlinks all cfs_rq's from the dying task group, it doesn't protect itself from getting interrupted. If the timer interrupt triggers while we iterate over all CPUs or after unregister_fair_sched_group() has finished but prior to unlinking the task group, sched_cfs_period_timer() will execute and walk the list of task groups, trying to unthrottle cfs_rq's, i.e. re-add them to the dying task group. These will later -- in free_fair_sched_group() -- be kfree()'ed while still being linked, leading to the fireworks Kevin and Michal are seeing. To fix this race, ensure the dying task group gets unlinked first. However, simply switching the order of unregistering and unlinking the task group isn't sufficient, as concurrent RCU walkers might still see it, as can be seen below: CPU1: CPU2: : timer IRQ: : do_sched_cfs_period_timer(): : : : distribute_cfs_runtime(): : rcu_read_lock(); : : : unthrottle_cfs_rq(): sched_offline_group(): : : walk_tg_tree_from(…,tg_unthrottle_up,…): list_del_rcu(&tg->list); : (1) : list_for_each_entry_rcu(child, &parent->children, siblings) : : (2) list_del_rcu(&tg->siblings); : : tg_unthrottle_up(): unregister_fair_sched_group(): struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; : : list_del_leaf_cfs_rq(tg->cfs_rq[cpu]); : : : : if (!cfs_rq_is_decayed(cfs_rq) || cfs_rq->nr_running) (3) : list_add_leaf_cfs_rq(cfs_rq); : : : : : : : : : : (4) : rcu_read_unlock(); CPU 2 walks the task group list in parallel to sched_offline_group(), specifically, it'll read the soon to be unlinked task group entry at (1). Unlinking it on CPU 1 at (2) therefore won't prevent CPU 2 from still passing it on to tg_unthrottle_up(). CPU 1 now tries to unlink all cfs_rq's via list_del_leaf_cfs_rq() in unregister_fair_sched_group(). Meanwhile CPU 2 will re-add some of these at (3), which is the cause of the UAF later on. To prevent this additional race from happening, we need to wait until walk_tg_tree_from() has finished traversing the task groups, i.e. after the RCU read critical section ends in (4). Afterwards we're safe to call unregister_fair_sched_group(), as each new walk won't see the dying task group any more. On top of that, we need to wait yet another RCU grace period after unregister_fair_sched_group() to ensure print_cfs_stats(), which might run concurrently, always sees valid objects, i.e. not already free'd ones. This patch survives Michal's reproducer[2] for 8h+ now, which used to trigger within minutes before. [1] https://lore.kernel.org/lkml/20211011172236.11223-1-mkoutny@suse.com/ [2] https://lore.kernel.org/lkml/20211102160228.GA57072@blackbody.suse.cz/ Fixes: a7b359fc6a37 ("sched/fair: Correctly insert cfs_rq's to list on unthrottle") [peterz: shuffle code around a bit] Reported-by: Kevin Tanguy <kevin.tanguy@corp.ovh.com> Signed-off-by: Mathias Krause <minipli@grsecurity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-11-11sched/core: Mitigate race cpus_share_cache()/update_top_cache_domain()Vincent Donnefort1-0/+3
Nothing protects the access to the per_cpu variable sd_llc_id. When testing the same CPU (i.e. this_cpu == that_cpu), a race condition exists with update_top_cache_domain(). One scenario being: CPU1 CPU2 ================================================================== per_cpu(sd_llc_id, CPUX) => 0 partition_sched_domains_locked() detach_destroy_domains() cpus_share_cache(CPUX, CPUX) update_top_cache_domain(CPUX) per_cpu(sd_llc_id, CPUX) => 0 per_cpu(sd_llc_id, CPUX) = CPUX per_cpu(sd_llc_id, CPUX) => CPUX return false ttwu_queue_cond() wouldn't catch smp_processor_id() == cpu and the result is a warning triggered from ttwu_queue_wakelist(). Avoid a such race in cpus_share_cache() by always returning true when this_cpu == that_cpu. Fixes: 518cd6234178 ("sched: Only queue remote wakeups when crossing cache boundaries") Reported-by: Jing-Ting Wu <jing-ting.wu@mediatek.com> Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lore.kernel.org/r/20211104175120.857087-1-vincent.donnefort@arm.com
2021-11-11Merge tag 'kernel.sys.v5.16' of ↵Linus Torvalds1-0/+4
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull prctl updates from Christian Brauner: "This contains the missing prctl uapi pieces for PR_SCHED_CORE. In order to activate core scheduling the caller is expected to specify the scope of the new core scheduling domain. For example, passing 2 in the 4th argument of prctl(PR_SCHED_CORE, PR_SCHED_CORE_CREATE, <pid>, 2, 0); would indicate that the new core scheduling domain encompasses all tasks in the process group of <pid>. Specifying 0 would only create a core scheduling domain for the thread identified by <pid> and 2 would encompass the whole thread-group of <pid>. Note, the values 0, 1, and 2 correspond to PIDTYPE_PID, PIDTYPE_TGID, and PIDTYPE_PGID. A first version tried to expose those values directly to which I objected because: - PIDTYPE_* is an enum that is kernel internal which we should not expose to userspace directly. - PIDTYPE_* indicates what a given struct pid is used for it doesn't express a scope. But what the 4th argument of PR_SCHED_CORE prctl() expresses is the scope of the operation, i.e. the scope of the core scheduling domain at creation time. So Eugene's patch now simply introduces three new defines PR_SCHED_CORE_SCOPE_THREAD, PR_SCHED_CORE_SCOPE_THREAD_GROUP, and PR_SCHED_CORE_SCOPE_PROCESS_GROUP. They simply express what happens. This has been on the mailing list for quite a while with all relevant scheduler folks Cced. I announced multiple times that I'd pick this up if I don't see or her anyone else doing it. None of this touches proper scheduler code but only concerns uapi so I think this is fine. With core scheduling being quite common now for vm managers (e.g. moving individual vcpu threads into their own core scheduling domain) and container managers (e.g. moving the init process into its own core scheduling domain and letting all created children inherit it) having to rely on raw numbers passed as the 4th argument in prctl() is a bit annoying and everyone is starting to come up with their own defines" * tag 'kernel.sys.v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: uapi/linux/prctl: provide macro definitions for the PR_SCHED_CORE type argument
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