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2020-03-30Merge branch 'pm-qos'Rafael J. Wysocki1-37/+36
* pm-qos: (30 commits) PM: QoS: annotate data races in pm_qos_*_value() Documentation: power: fix pm_qos_interface.rst format warning PM: QoS: Make CPU latency QoS depend on CONFIG_CPU_IDLE Documentation: PM: QoS: Update to reflect previous code changes PM: QoS: Update file information comments PM: QoS: Drop PM_QOS_CPU_DMA_LATENCY and rename related functions sound: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: usb: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: tty: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: spi: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: net: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: mmc: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: media: Call cpu_latency_qos_*() instead of pm_qos_*() drivers: hsi: Call cpu_latency_qos_*() instead of pm_qos_*() drm: i915: Call cpu_latency_qos_*() instead of pm_qos_*() x86: platform: iosf_mbi: Call cpu_latency_qos_*() instead of pm_qos_*() cpuidle: Call cpu_latency_qos_limit() instead of pm_qos_request() PM: QoS: Add CPU latency QoS API wrappers PM: QoS: Adjust pm_qos_request() signature and reorder pm_qos.h PM: QoS: Simplify definitions of CPU latency QoS trace events ...
2020-03-25block/diskstats: more accurate approximation of io_ticks for slow disksKonstantin Khlebnikov1-1/+4
Currently io_ticks is approximated by adding one at each start and end of requests if jiffies counter has changed. This works perfectly for requests shorter than a jiffy or if one of requests starts/ends at each jiffy. If disk executes just one request at a time and they are longer than two jiffies then only first and last jiffies will be accounted. Fix is simple: at the end of request add up into io_ticks jiffies passed since last update rather than just one jiffy. Example: common HDD executes random read 4k requests around 12ms. fio --name=test --filename=/dev/sdb --rw=randread --direct=1 --runtime=30 & iostat -x 10 sdb Note changes of iostat's "%util" 8,43% -> 99,99% before/after patch: Before: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdb 0,00 0,00 82,60 0,00 330,40 0,00 8,00 0,96 12,09 12,09 0,00 1,02 8,43 After: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdb 0,00 0,00 82,50 0,00 330,00 0,00 8,00 1,00 12,10 12,10 0,00 12,12 99,99 Now io_ticks does not loose time between start and end of requests, but for queue-depth > 1 some I/O time between adjacent starts might be lost. For load estimation "%util" is not as useful as average queue length, but it clearly shows how often disk queue is completely empty. Fixes: 5b18b5a73760 ("block: delete part_round_stats and switch to less precise counting") Signed-off-by: Konstantin Khlebnikov <[email protected]> Reviewed-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
2020-03-24Merge branch 'for-mingo' of ↵Ingo Molnar1-0/+19
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU changes from Paul E. McKenney: - Make kfree_rcu() use kfree_bulk() for added performance - RCU updates - Callback-overload handling updates - Tasks-RCU KCSAN and sparse updates - Locking torture test and RCU torture test updates - Documentation updates - Miscellaneous fixes Signed-off-by: Ingo Molnar <[email protected]>
2020-03-24x86/vmware: Enable steal time accountingAlexey Makhalov1-1/+1
Set paravirt_steal_rq_enabled if steal clock present. paravirt_steal_rq_enabled is used in sched/core.c to adjust task progress by offsetting stolen time. Use 'no-steal-acc' off switch (share same name with KVM) to disable steal time accounting. Signed-off-by: Alexey Makhalov <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Reviewed-by: Thomas Hellstrom <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-21Merge branches 'doc.2020.02.27a', 'fixes.2020.03.21a', ↵Paul E. McKenney1-0/+19
'kfree_rcu.2020.02.20a', 'locktorture.2020.02.20a', 'ovld.2020.02.20a', 'rcu-tasks.2020.02.20a', 'srcu.2020.02.20a' and 'torture.2020.02.20a' into HEAD doc.2020.02.27a: Documentation updates. fixes.2020.03.21a: Miscellaneous fixes. kfree_rcu.2020.02.20a: Updates to kfree_rcu(). locktorture.2020.02.20a: Lock torture-test updates. ovld.2020.02.20a: Updates to callback-overload handling. rcu-tasks.2020.02.20a: RCU-tasks updates. srcu.2020.02.20a: SRCU updates. torture.2020.02.20a: Torture-test updates.
2020-03-17docs: Add reference in binfmt-misc.rstRomuald Brunet1-2/+2
While looking at the binfmt-misc documentation I noticed that there is a reference to the “java” example that could be a direct link. This patch simply adds the link without changing the HTML output. Signed-off-by: Romuald Brunet <[email protected]> Signed-off-by: Jiri Kosina <[email protected]>
2020-03-14Documentation: intel_pstate: update links for referencesAlex Hung1-2/+2
URLs for presentation and Intel Software Developer’s Manual are updated as they were using "http" which are gradually replaced by "https". Signed-off-by: Alex Hung <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
2020-03-14acpi/x86: add a kernel parameter to disable ACPI BGRTAlex Hung1-0/+3
BGRT is for displaying seamless OEM logo from booting to login screen; however, this mechanism does not always work well on all configurations and the OEM logo can be displayed multiple times. This looks worse than without BGRT enabled. This patch adds a kernel parameter to disable BGRT in boot time. This is easier than re-compiling a kernel with CONFIG_ACPI_BGRT disabled. Signed-off-by: Alex Hung <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
2020-03-13Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller1-1/+2
Daniel Borkmann says: ==================== pull-request: bpf-next 2020-03-13 The following pull-request contains BPF updates for your *net-next* tree. We've added 86 non-merge commits during the last 12 day(s) which contain a total of 107 files changed, 5771 insertions(+), 1700 deletions(-). The main changes are: 1) Add modify_return attach type which allows to attach to a function via BPF trampoline and is run after the fentry and before the fexit programs and can pass a return code to the original caller, from KP Singh. 2) Generalize BPF's kallsyms handling and add BPF trampoline and dispatcher objects to be visible in /proc/kallsyms so they can be annotated in stack traces, from Jiri Olsa. 3) Extend BPF sockmap to allow for UDP next to existing TCP support in order in order to enable this for BPF based socket dispatch, from Lorenz Bauer. 4) Introduce a new bpftool 'prog profile' command which attaches to existing BPF programs via fentry and fexit hooks and reads out hardware counters during that period, from Song Liu. Example usage: bpftool prog profile id 337 duration 3 cycles instructions llc_misses 4228 run_cnt 3403698 cycles (84.08%) 3525294 instructions # 1.04 insn per cycle (84.05%) 13 llc_misses # 3.69 LLC misses per million isns (83.50%) 5) Batch of improvements to libbpf, bpftool and BPF selftests. Also addition of a new bpf_link abstraction to keep in particular BPF tracing programs attached even when the applicaion owning them exits, from Andrii Nakryiko. 6) New bpf_get_current_pid_tgid() helper for tracing to perform PID filtering and which returns the PID as seen by the init namespace, from Carlos Neira. 7) Refactor of RISC-V JIT code to move out common pieces and addition of a new RV32G BPF JIT compiler, from Luke Nelson. 8) Add gso_size context member to __sk_buff in order to be able to know whether a given skb is GSO or not, from Willem de Bruijn. 9) Add a new bpf_xdp_output() helper which reuses XDP's existing perf RB output implementation but can be called from tracepoint programs, from Eelco Chaudron. ==================== Signed-off-by: David S. Miller <[email protected]>
2020-03-10Documentation: Better document the softlockup_panic sysctlGuilherme G. Piccoli2-4/+18
Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the softlockup_panic sysctl, but didn't add information about it to the file Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly wasn't rst and had other name!). This patch just adds the respective documentation and references it from the corresponding entry in Documentation/admin-guide/kernel-parameters.txt. This patch was strongly based on Scott Wood's commit d22881dc13b6 ("Documentation: Better document the hardlockup_panic sysctl"). Reviewed-by: Kees Cook <[email protected]> Signed-off-by: Guilherme G. Piccoli <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-10docs: hw-vuln: tsx_async_abort.rst: get rid of an unused refMauro Carvalho Chehab1-2/+0
The virt_mechanism reference there points to a section called elsewhere (Virtualization mitigation). Also, it is not used anywere. Besides that, it conflicts with a label with the same name inside: Documentation/admin-guide/hw-vuln/mds.rst Perhaps added due to some cut-and-paste? Anyway, as this is not used, let's just get rid of it. Signed-off-by: Mauro Carvalho Chehab <[email protected]> Link: https://lore.kernel.org/r/681c8e2916bf4943ac2277f181668bfbc5fdbc01.1583250595.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-10docs: perf: imx-ddr.rst: get rid of a warningMauro Carvalho Chehab1-1/+2
Documentation/admin-guide/perf/imx-ddr.rst:47: WARNING: Unexpected indentation. Signed-off-by: Mauro Carvalho Chehab <[email protected]> Link: https://lore.kernel.org/r/b27b54bd4f847032fd33313d6497ff320c0f3d78.1583250595.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-10docs: admin-guide: binfmt-misc: Improve the titleJonathan Neuschäfer1-2/+2
Trim the title a bit, since it's relatively long. Add `binfmt_misc` to make it easier to search for the feature by its common name. Signed-off-by: Jonathan Neuschäfer <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-09Merge 5.6-rc5 into driver-core-nextGreg Kroah-Hartman3-5/+37
We need the driver core and debugfs changes in here as well. Signed-off-by: Greg Kroah-Hartman <[email protected]>
2020-03-09Merge 5.6-rc5 into char-misc-nextGreg Kroah-Hartman3-5/+37
We need the binder and other fixes in here as well. Signed-off-by: Greg Kroah-Hartman <[email protected]>
2020-03-06sched/fair: Enable tuning of decay periodThara Gopinath1-0/+16
Thermal pressure follows pelt signals which means the decay period for thermal pressure is the default pelt decay period. Depending on SoC characteristics and thermal activity, it might be beneficial to decay thermal pressure slower, but still in-tune with the pelt signals. One way to achieve this is to provide a command line parameter to set a decay shift parameter to an integer between 0 and 10. Signed-off-by: Thara Gopinath <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
2020-03-06Merge branch 'acpi-doc'Rafael J. Wysocki1-2/+2
* acpi-doc: Documentation/admin-guide/acpi: fix fan_performance_states.rst warnings
2020-03-05bpf, doc: Add BPF JIT for RV32G to BPF documentationLuke Nelson1-1/+2
Update filter.txt and admin-guide to mention the BPF JIT for RV32G. Co-developed-by: Xi Wang <[email protected]> Signed-off-by: Xi Wang <[email protected]> Signed-off-by: Luke Nelson <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Reviewed-by: Björn Töpel <[email protected]> Acked-by: Björn Töpel <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
2020-03-04of: property: Delete of_devlink kernel commandline optionSaravana Kannan1-6/+0
With the addition of fw_devlink kernel commandline option, of_devlink is redundant and not useful anymore. So, delete it. Acked-by: Rob Herring <[email protected]> Signed-off-by: Saravana Kannan <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
2020-03-04driver core: Add fw_devlink kernel commandline optionSaravana Kannan1-0/+18
fwnode_operations.add_links allows creating device links from information provided by firmware. fwnode_operations.add_links is currently implemented only by OF/devicetree code and a specific case of efi. However, there's nothing preventing ACPI or other firmware types from implementing it. The OF implementation is currently controlled by a kernel commandline parameter called of_devlink. Since this feature is generic isn't limited to OF, add a generic fw_devlink kernel commandline parameter to control this feature across firmware types. Signed-off-by: Saravana Kannan <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
2020-03-02Documentation: nfsroot.rst: Fix references to nfsroot.rstNiklas Söderlund1-4/+4
When converting and moving nfsroot.txt to nfsroot.rst the references to the old text file was not updated to match the change, fix this. Fixes: f9a9349846f92b2d ("Documentation: nfsroot.txt: convert to ReST") Signed-off-by: Niklas Söderlund <[email protected]> Reviewed-by: Geert Uytterhoeven <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02Documentation: kthread: Fix WQ_SYSFS workqueues path nameZenghui Yu1-1/+1
The set of WQ_SYSFS workqueues should be displayed using "ls /sys/devices/virtual/workqueue", add the missing '/'. Signed-off-by: Zenghui Yu <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02doc: cgroup: improve formatting of referencesJakub Kicinski2-4/+6
Annotate references to other documents to make them clickable. Signed-off-by: Jakub Kicinski <[email protected]> Acked-by: Johannes Weiner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02doc: cgroup: improve formatting of cpuset examplesJakub Kicinski1-2/+2
We need literal sections otherwise the entire example is rendered as a single line. Signed-off-by: Jakub Kicinski <[email protected]> Acked-by: Johannes Weiner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02doc: cgroup: improve formatting of io exampleJakub Kicinski1-1/+1
We need a literal section, like few paragraphs below. Signed-off-by: Jakub Kicinski <[email protected]> Acked-by: Johannes Weiner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02doc: cgroup: improve formatting of mem statsJakub Kicinski1-12/+0
If there is an empty line between item and description Sphinx does not emphasize the item. First half of the list does not have the empty line and is emphasized correctly. Signed-off-by: Jakub Kicinski <[email protected]> Acked-by: Johannes Weiner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02doc: cgroup: improve formattingJakub Kicinski1-1/+1
Fix tabs vs spaces issue which cases the line to be considered a new list entry. Signed-off-by: Jakub Kicinski <[email protected]> Acked-by: Johannes Weiner <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02docs: admin-guide: kernel-parameters: Document earlycon options for i.MX UARTsJonathan Neuschäfer1-0/+6
drivers/tty/serial/imx.c implements these earlycon options. Signed-off-by: Jonathan Neuschäfer <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jonathan Corbet <[email protected]>
2020-03-02Documentation: cpufreq: Move legacy driver documentationRafael J. Wysocki2-0/+275
There are three legacy driver documents in Documentation/cpu-freq/ that were added years ago and converting them each to the .rst format is rather pointless, even though there is some value in preserving them. However, if they are preserved, they need to go into the admin-guide part of cpufreq documentation where they belong (at least to a certain extent). To preserve them with minimum amount of changes and put them into the right place, and make it possible to process them into HTML (and other formats) along with the rest of the documentation, move them each as a "literal text" block into a separate section of a single .rst "wrapper" file under Documentation/admin-guide/pm/. While at it, repair the PCC specification URL in one of them. Signed-off-by: Rafael J. Wysocki <[email protected]>
2020-02-28Merge tag 'acpi-5.6-rc4' of ↵Linus Torvalds1-0/+4
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull ACPI fixes from Rafael Wysocki: "Fix a couple of configuration issues in the ACPI watchdog (WDAT) driver (Mika Westerberg) and make it possible to disable that driver at boot time in case it still does not work as expected (Jean Delvare)" * tag 'acpi-5.6-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI: watchdog: Set default timeout in probe ACPI: watchdog: Fix gas->access_width usage ACPICA: Introduce ACPI_ACCESS_BYTE_WIDTH() macro ACPI: watchdog: Allow disabling WDAT at boot
2020-02-27s390/protvirt: introduce host side setupVasily Gorbik1-0/+5
Add "prot_virt" command line option which controls if the kernel protected VMs support is enabled at early boot time. This has to be done early, because it needs large amounts of memory and will disable some features like STP time sync for the lpar. Extend ultravisor info definitions and expose it via uv_info struct filled in during startup. Signed-off-by: Vasily Gorbik <[email protected]> Reviewed-by: Thomas Huth <[email protected]> Acked-by: David Hildenbrand <[email protected]> Reviewed-by: Cornelia Huck <[email protected]> Acked-by: Christian Borntraeger <[email protected]> [[email protected]: patch merging, splitting, fixing] Signed-off-by: Christian Borntraeger <[email protected]>
2020-02-26Merge tag 'trace-v5.6-rc2' of ↵Linus Torvalds1-3/+31
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing and bootconfig updates: "Fixes and changes to bootconfig before it goes live in a release. Change in API of bootconfig (before it comes live in a release): - Have a magic value "BOOTCONFIG" in initrd to know a bootconfig exists - Set CONFIG_BOOT_CONFIG to 'n' by default - Show error if "bootconfig" on cmdline but not compiled in - Prevent redefining the same value - Have a way to append values - Added a SELECT BLK_DEV_INITRD to fix a build failure Synthetic event fixes: - Switch to raw_smp_processor_id() for recording CPU value in preempt section. (No care for what the value actually is) - Fix samples always recording u64 values - Fix endianess - Check number of values matches number of fields - Fix a printing bug Fix of trace_printk() breaking postponed start up tests Make a function static that is only used in a single file" * tag 'trace-v5.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: bootconfig: Fix CONFIG_BOOTTIME_TRACING dependency issue bootconfig: Add append value operator support bootconfig: Prohibit re-defining value on same key bootconfig: Print array as multiple commands for legacy command line bootconfig: Reject subkey and value on same parent key tools/bootconfig: Remove unneeded error message silencer bootconfig: Add bootconfig magic word for indicating bootconfig explicitly bootconfig: Set CONFIG_BOOT_CONFIG=n by default tracing: Clear trace_state when starting trace bootconfig: Mark boot_config_checksum() static tracing: Disable trace_printk() on post poned tests tracing: Have synthetic event test use raw_smp_processor_id() tracing: Fix number printing bug in print_synth_event() tracing: Check that number of vals matches number of synth event fields tracing: Make synth_event trace functions endian-correct tracing: Make sure synth_event_trace() example always uses u64
2020-02-25docs: add a script to check sysctl docsStephen Kitt1-0/+3
This script allows sysctl documentation to be checked against the kernel source code, to identify missing or obsolete entries. Running it against 5.5 shows for example that sysctl/kernel.rst has two obsolete entries and is missing 52 entries. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-25Documentation: fix a typo for intel_iommu=nobounceAlex Hung1-1/+1
"untrusted" was mis-spelled as "unstrusted" Signed-off-by: Alex Hung <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-25docs: sysctl/kernel: document acpi_video_flagsStephen Kitt1-2/+9
Based on the implementation in arch/x86/kernel/acpi/sleep.c, in particular the acpi_sleep_setup() function. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-21bootconfig: Add append value operator supportMasami Hiramatsu1-1/+9
Add append value operator "+=" support to bootconfig syntax. With this operator, user can add new value to the key as an entry of array instead of overwriting. For example, foo = bar ... foo += baz Then the key "foo" has "bar" and "baz" values as an array. Link: http://lkml.kernel.org/r/158227283195.12842.8310503105963275584.stgit@devnote2 Signed-off-by: Masami Hiramatsu <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]>
2020-02-21bootconfig: Prohibit re-defining value on same keyMasami Hiramatsu1-1/+10
Currently, bootconfig adds a new value on the existing key to the tail of an array. But this looks a bit confusing because an admin can easily rewrite the original value in the same config file. This rejects the following value re-definition. key = value1 ... key = value2 You should rewrite value1 to value2 in this case. Link: http://lkml.kernel.org/r/158227282199.12842.10110929876059658601.stgit@devnote2 Suggested-by: Steven Rostedt (VMware) <[email protected]> Signed-off-by: Masami Hiramatsu <[email protected]> [ Fixed spelling of arraies to arrays ] Signed-off-by: Steven Rostedt (VMware) <[email protected]>
2020-02-20torture: Allow disabling of boottime CPU-hotplug torture operationsPaul E. McKenney1-0/+4
In theory, RCU-hotplug operations are supposed to work as soon as there is more than one CPU online. However, in practice, in normal production there is no way to make them happen until userspace is up and running. Besides which, on smaller systems, rcutorture doesn't start doing hotplug operations until 30 seconds after the start of boot, which on most systems also means the better part of 30 seconds after the end of boot. This commit therefore provides a new torture.disable_onoff_at_boot kernel boot parameter that suppresses CPU-hotplug torture operations until about the time that init is spawned. Of course, if you know of a need for boottime CPU-hotplug operations, then you should avoid passing this argument to any of the torture tests. You might also want to look at the splats linked to below. Link: https://lore.kernel.org/lkml/20191206185208.GA25636@paulmck-ThinkPad-P72/ Signed-off-by: Paul E. McKenney <[email protected]>
2020-02-20rcutorture: Allow boottime stall warnings to be suppressedPaul E. McKenney1-0/+6
In normal production, an RCU CPU stall warning at boottime is often just as bad as at any other time. In fact, given the desire for fast boot, any sort of long-term stall at boot is a bad idea. However, heavy rcutorture testing on large hyperthreaded systems can generate boottime RCU CPU stalls as a matter of course. This commit therefore provides a kernel boot parameter that suppresses reporting of boottime RCU CPU stall warnings and similarly of rcutorture writer stalls. Signed-off-by: Paul E. McKenney <[email protected]>
2020-02-20rcu: React to callback overload by aggressively seeking quiescent statesPaul E. McKenney1-0/+9
In default configutions, RCU currently waits at least 100 milliseconds before asking cond_resched() and/or resched_rcu() for help seeking quiescent states to end a grace period. But 100 milliseconds can be one good long time during an RCU callback flood, for example, as can happen when user processes repeatedly open and close files in a tight loop. These 100-millisecond gaps in successive grace periods during a callback flood can result in excessive numbers of callbacks piling up, unnecessarily increasing memory footprint. This commit therefore asks cond_resched() and/or resched_rcu() for help as early as the first FQS scan when at least one of the CPUs has more than 20,000 callbacks queued, a number that can be changed using the new rcutree.qovld kernel boot parameter. An auxiliary qovld_calc variable is used to avoid acquisition of locks that have not yet been initialized. Early tests indicate that this reduces the RCU-callback memory footprint during rcutorture floods by from 50% to 4x, depending on configuration. Reported-by: Joel Fernandes (Google) <[email protected]> Reported-by: Tejun Heo <[email protected]> [ paulmck: Fix bug located by Qian Cai. ] Signed-off-by: Paul E. McKenney <[email protected]> Tested-by: Dexuan Cui <[email protected]> Tested-by: Qian Cai <[email protected]>
2020-02-20bootconfig: Reject subkey and value on same parent keyMasami Hiramatsu1-0/+7
Reject if a value node is mixed with subkey node on same parent key node. A value node can not co-exist with subkey node under some key node, e.g. key = value key.subkey = another-value This is not be allowed because bootconfig API is not designed to handle such case. Link: http://lkml.kernel.org/r/158220115232.26565.7792340045009731803.stgit@devnote2 Signed-off-by: Masami Hiramatsu <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]>
2020-02-20bootconfig: Add bootconfig magic word for indicating bootconfig explicitlyMasami Hiramatsu1-3/+7
Add bootconfig magic word to the end of bootconfig on initrd image for indicating explicitly the bootconfig is there. Also tools/bootconfig treats wrong size or wrong checksum or parse error as an error, because if there is a bootconfig magic word, there must be a bootconfig. The bootconfig magic word is "#BOOTCONFIG\n", 12 bytes word. Thus the block image of the initrd file with bootconfig is as follows. [Initrd][bootconfig][size][csum][#BOOTCONFIG\n] Link: http://lkml.kernel.org/r/158220112263.26565.3944814205960612841.stgit@devnote2 Suggested-by: Steven Rostedt <[email protected]> Signed-off-by: Masami Hiramatsu <[email protected]> Signed-off-by: Steven Rostedt (VMware) <[email protected]>
2020-02-20x86/split_lock: Enable split lock detection by kernelPeter Zijlstra (Intel)1-0/+22
A split-lock occurs when an atomic instruction operates on data that spans two cache lines. In order to maintain atomicity the core takes a global bus lock. This is typically >1000 cycles slower than an atomic operation within a cache line. It also disrupts performance on other cores (which must wait for the bus lock to be released before their memory operations can complete). For real-time systems this may mean missing deadlines. For other systems it may just be very annoying. Some CPUs have the capability to raise an #AC trap when a split lock is attempted. Provide a command line option to give the user choices on how to handle this: split_lock_detect= off - not enabled (no traps for split locks) warn - warn once when an application does a split lock, but allow it to continue running. fatal - Send SIGBUS to applications that cause split lock On systems that support split lock detection the default is "warn". Note that if the kernel hits a split lock in any mode other than "off" it will OOPs. One implementation wrinkle is that the MSR to control the split lock detection is per-core, not per thread. This might result in some short lived races on HT systems in "warn" mode if Linux tries to enable on one thread while disabling on the other. Race analysis by Sean Christopherson: - Toggling of split-lock is only done in "warn" mode. Worst case scenario of a race is that a misbehaving task will generate multiple #AC exceptions on the same instruction. And this race will only occur if both siblings are running tasks that generate split-lock #ACs, e.g. a race where sibling threads are writing different values will only occur if CPUx is disabling split-lock after an #AC and CPUy is re-enabling split-lock after *its* previous task generated an #AC. - Transitioning between off/warn/fatal modes at runtime isn't supported and disabling is tracked per task, so hardware will always reach a steady state that matches the configured mode. I.e. split-lock is guaranteed to be enabled in hardware once all _TIF_SLD threads have been scheduled out. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Co-developed-by: Fenghua Yu <[email protected]> Signed-off-by: Fenghua Yu <[email protected]> Co-developed-by: Tony Luck <[email protected]> Signed-off-by: Tony Luck <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Link: https://lore.kernel.org/r/[email protected]
2020-02-20Documentation/admin-guide/acpi: fix fan_performance_states.rst warningsRandy Dunlap1-2/+2
Fix Sphinx format warnings in fan_performace_states.rst by adding indentation. Documentation/admin-guide/acpi/fan_performance_states.rst:21: WARNING: Literal block ends without a blank line; unexpected unindent. Documentation/admin-guide/acpi/fan_performance_states.rst:41: WARNING: Literal block expected; none found. Signed-off-by: Randy Dunlap <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
2020-02-19docs: admin-guide: edid: Clarify where to run "make"Jonathan Neuschäfer1-1/+1
When both the documentation and the data files lived in Documentation/EDID, this wasn't necessary, but both have been moved to other directories in the meantime. Signed-off-by: Jonathan Neuschäfer <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-19docs: admin-guide: Move edid.rst from driver-apiJonathan Neuschäfer2-0/+61
This document describes actions that an admin can do, rather than interfaces available to driver developers, so admin-guide seems to be a more appropriate place for it. Signed-off-by: Jonathan Neuschäfer <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-19docs: sysctl/kernel: remove rtsig entriesStephen Kitt1-10/+0
These have no corresponding code in the kernel. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-19docs: document panic fully in sysctl/kernel.rstStephen Kitt1-3/+9
The description of panic doesn’t cover all the supported scenarios; this patch fixes that, describing the three possibilities (no reboot, immediate reboot, reboot after a delay). Based on the implementation in kernel/panic.c. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-19docs: document stop-a in sysctl/kernel.rstStephen Kitt1-0/+10
This describes the SPARC-specific stop-a sysctl entry, which was previously listed in kernel.rst but not documented. Base on the implementation in arch/sparc/kernel/setup_{32,64}.c and kernel/panic.c. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
2020-02-19docs: add missing IPC documentation in sysctl/kernel.rstStephen Kitt1-0/+12
This adds short descriptions of msgmax, msgmnb, msgmni, and shmmni, which were previously listed in kernel.rst but not described. Signed-off-by: Stephen Kitt <[email protected]> Signed-off-by: Jonathan Corbet <[email protected]>
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