lwn.git/kernel/sched/debug.c, branch v5.2-rc2

sched/debug: Fix spelling mistake "logaritmic" -> "logarithmic"

2019-04-19T19:04:49+00:00

Signed-off-by: Colin Ian King Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kernel-janitors@vger.kernel.org Link: http://lkml.kernel.org/r/20181128152350.13622-1-colin.king@canonical.com Signed-off-by: Ingo Molnar

sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK

2019-02-04T08:13:21+00:00

register_sched_domain_sysctl() copies the cpu_possible_mask into sd_sysctl_cpus, but only if sd_sysctl_cpus hasn't already been allocated (ie, CONFIG_CPUMASK_OFFSTACK is set). However, when CONFIG_CPUMASK_OFFSTACK is not set, sd_sysctl_cpus is left uninitialized (all zeroes) and the kernel may fail to initialize sched_domain sysctl entries for all possible CPUs. This is visible to the user if the kernel is booted with maxcpus=n, or if ACPI tables have been modified to leave CPUs offline, and then checking for missing /proc/sys/kernel/sched_domain/cpu* entries. Fix this by separating the allocation and initialization, and adding a flag to initialize the possible CPU entries while system booting only. Tested-by: Syuuichirou Ishii Tested-by: Tarumizu, Kohei Signed-off-by: Hidetoshi Seto Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Masayoshi Mizuma Acked-by: Joe Lawrence Cc: Linus Torvalds Cc: Masayoshi Mizuma Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190129151245.5073-1-msys.mizuma@gmail.com Signed-off-by: Ingo Molnar

jump_label: move 'asm goto' support test to Kconfig

2019-01-06T00:46:51+00:00

Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label". The jump label is controlled by HAVE_JUMP_LABEL, which is defined like this: #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) # define HAVE_JUMP_LABEL #endif We can improve this by testing 'asm goto' support in Kconfig, then make JUMP_LABEL depend on CC_HAS_ASM_GOTO. Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will match to the real kernel capability. Signed-off-by: Masahiro Yamada Acked-by: Michael Ellerman (powerpc) Tested-by: Sedat Dilek

sched/core: Create task_has_idle_policy() helper

2018-11-12T05:17:52+00:00

We already have task_has_rt_policy() and task_has_dl_policy() helpers, create task_has_idle_policy() as well and update sched core to start using it. While at it, use task_has_dl_policy() at one more place. Signed-off-by: Viresh Kumar Signed-off-by: Peter Zijlstra (Intel) Acked-by: Daniel Lezcano Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vincent Guittot Link: http://lkml.kernel.org/r/ce3915d5b490fc81af926a3b6bfb775e7188e005.1541416894.git.viresh.kumar@linaro.org Signed-off-by: Ingo Molnar

sched/debug: Fix potential deadlock when writing to sched_features

2018-09-10T08:13:45+00:00

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-gcd3f77d74ac3-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-gcd3f77d74ac3-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 Signed-off-by: Jiada Wang Signed-off-by: Peter Zijlstra (Intel) Cc: Eugeniu Rosca Cc: George G. Davis Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180731121222.26195-1-jiada_wang@mentor.com Signed-off-by: Ingo Molnar

Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-08-14T01:28:19+00:00

Pull x86 timer updates from Thomas Gleixner: "Early TSC based time stamping to allow better boot time analysis. This comes with a general cleanup of the TSC calibration code which grew warts and duct taping over the years and removes 250 lines of code. Initiated and mostly implemented by Pavel with help from various folks" * 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits) x86/kvmclock: Mark kvm_get_preset_lpj() as __init x86/tsc: Consolidate init code sched/clock: Disable interrupts when calling generic_sched_clock_init() timekeeping: Prevent false warning when persistent clock is not available sched/clock: Close a hole in sched_clock_init() x86/tsc: Make use of tsc_calibrate_cpu_early() x86/tsc: Split native_calibrate_cpu() into early and late parts sched/clock: Use static key for sched_clock_running sched/clock: Enable sched clock early sched/clock: Move sched clock initialization and merge with generic clock x86/tsc: Use TSC as sched clock early x86/tsc: Initialize cyc2ns when tsc frequency is determined x86/tsc: Calibrate tsc only once ARM/time: Remove read_boot_clock64() s390/time: Remove read_boot_clock64() timekeeping: Default boot time offset to local_clock() timekeeping: Replace read_boot_clock64() with read_persistent_wall_and_boot_offset() s390/time: Add read_persistent_wall_and_boot_offset() x86/xen/time: Output xen sched_clock time from 0 x86/xen/time: Initialize pv xen time in init_hypervisor_platform() ...

sched/debug: Reverse the order of printing faults

2018-07-25T09:41:07+00:00

Fix the order in which the private and shared numa faults are getting printed. No functional changes. Running SPECjbb2005 on a 4 node machine and comparing bops/JVM JVMS LAST_PATCH WITH_PATCH %CHANGE 16 25215.7 25375.3 0.63 1 72107 72617 0.70 Signed-off-by: Srikar Dronamraju Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Rik van Riel Acked-by: Mel Gorman Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1529514181-9842-7-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar

sched/clock: Use static key for sched_clock_running

2018-07-19T22:02:43+00:00

sched_clock_running may be read every time sched_clock_cpu() is called. Yet, this variable is updated only twice during boot, and never changes again, therefore it is better to make it a static key. Signed-off-by: Pavel Tatashin Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Cc: steven.sistare@oracle.com Cc: daniel.m.jordan@oracle.com Cc: linux@armlinux.org.uk Cc: schwidefsky@de.ibm.com Cc: heiko.carstens@de.ibm.com Cc: john.stultz@linaro.org Cc: sboyd@codeaurora.org Cc: hpa@zytor.com Cc: douly.fnst@cn.fujitsu.com Cc: prarit@redhat.com Cc: feng.tang@intel.com Cc: pmladek@suse.com Cc: gnomes@lxorguk.ukuu.org.uk Cc: linux-s390@vger.kernel.org Cc: boris.ostrovsky@oracle.com Cc: jgross@suse.com Cc: pbonzini@redhat.com Link: https://lkml.kernel.org/r/20180719205545.16512-25-pasha.tatashin@oracle.com

sched/debug: Use match_string() helper instead of open-coded logic

2018-06-21T13:45:31+00:00

match_string() returns the index of an array for a matching string, which can be used instead of the open coded variant. Signed-off-by: Yisheng Xie Reviewed-by: Andy Shevchenko Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lore.kernel.org/lkml/1527765086-19873-15-git-send-email-xieyisheng1@huawei.com Signed-off-by: Ingo Molnar

proc: introduce proc_create_seq{,_data}

2018-05-16T05:23:35+00:00

Variants of proc_create{,_data} that directly take a struct seq_operations argument and drastically reduces the boilerplate code in the callers. All trivial callers converted over. Signed-off-by: Christoph Hellwig