Pull KUnit updates from Shuah Khan:
"This consists of several fixes and an important feature to discourage
running KUnit tests on production systems. Running tests on a
production system could leave the system in a bad state.
Summary:
- Add a new taint type, TAINT_TEST to signal that a test has been
run.
This should discourage people from running these tests on
production systems, and to make it easier to tell if tests have
been run accidentally (by loading the wrong configuration, etc)
- Several documentation and tool enhancements and fixes"
* tag 'linux-kselftest-kunit-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits)
Documentation: KUnit: Fix example with compilation error
Documentation: kunit: Add CLI args for kunit_tool
kcsan: test: Add a .kunitconfig to run KCSAN tests
kunit: executor: Fix a memory leak on failure in kunit_filter_tests
clk: explicitly disable CONFIG_UML_PCI_OVER_VIRTIO in .kunitconfig
mmc: sdhci-of-aspeed: test: Use kunit_test_suite() macro
nitro_enclaves: test: Use kunit_test_suite() macro
thunderbolt: test: Use kunit_test_suite() macro
kunit: flatten kunit_suite*** to kunit_suite** in .kunit_test_suites
kunit: unify module and builtin suite definitions
selftest: Taint kernel when test module loaded
module: panic: Taint the kernel when selftest modules load
Documentation: kunit: fix example run_kunit func to allow spaces in args
Documentation: kunit: Cleanup run_wrapper, fix x-ref
kunit: test.h: fix a kernel-doc markup
kunit: tool: Enable virtio/PCI by default on UML
kunit: tool: make --kunitconfig repeatable, blindly concat
kunit: add coverage_uml.config to enable GCOV on UML
kunit: tool: refactor internal kconfig handling, allow overriding
kunit: tool: introduce --qemu_args
...
Pull documentation updates from Jonathan Corbet:
"This was a moderately busy cycle for documentation, but nothing
all that earth-shaking:
- More Chinese translations, and an update to the Italian
translations.
The Japanese, Korean, and traditional Chinese translations
are more-or-less unmaintained at this point, instead.
- Some build-system performance improvements.
- The removal of the archaic submitting-drivers.rst document,
with the movement of what useful material that remained into
other docs.
- Improvements to sphinx-pre-install to, hopefully, give more
useful suggestions.
- A number of build-warning fixes
Plus the usual collection of typo fixes, updates, and more"
* tag 'docs-6.0' of git://git.lwn.net/linux: (92 commits)
docs: efi-stub: Fix paths for x86 / arm stubs
Docs/zh_CN: Update the translation of sched-stats to 5.19-rc8
Docs/zh_CN: Update the translation of pci to 5.19-rc8
Docs/zh_CN: Update the translation of pci-iov-howto to 5.19-rc8
Docs/zh_CN: Update the translation of usage to 5.19-rc8
Docs/zh_CN: Update the translation of testing-overview to 5.19-rc8
Docs/zh_CN: Update the translation of sparse to 5.19-rc8
Docs/zh_CN: Update the translation of kasan to 5.19-rc8
Docs/zh_CN: Update the translation of iio_configfs to 5.19-rc8
doc:it_IT: align Italian documentation
docs: Remove spurious tag from admin-guide/mm/overcommit-accounting.rst
Documentation: process: Update email client instructions for Thunderbird
docs: ABI: correct QEMU fw_cfg spec path
doc/zh_CN: remove submitting-driver reference from docs
docs: zh_TW: align to submitting-drivers removal
docs: zh_CN: align to submitting-drivers removal
docs: ko_KR: howto: remove reference to removed submitting-drivers
docs: ja_JP: howto: remove reference to removed submitting-drivers
docs: it_IT: align to submitting-drivers removal
docs: process: remove outdated submitting-drivers.rst
...
Pull RCU updates from Paul McKenney:
- Documentation updates
- Miscellaneous fixes
- Callback-offload updates, perhaps most notably a new
RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be
offloaded at boot time, regardless of kernel boot parameters.
This is useful to battery-powered systems such as ChromeOS and
Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot
parameter prevents offloaded callbacks from interfering with
real-time workloads and with energy-efficiency mechanisms
- Polled grace-period updates, perhaps most notably making these APIs
account for both normal and expedited grace periods
- Tasks RCU updates, perhaps most notably reducing the CPU overhead of
RCU tasks trace grace periods by more than a factor of two on a
system with 15,000 tasks.
The reduction is expected to increase with the number of tasks, so it
seems reasonable to hypothesize that a system with 150,000 tasks
might see a 20-fold reduction in CPU overhead
- Torture-test updates
- Updates that merge RCU's dyntick-idle tracking into context tracking,
thus reducing the overhead of transitioning to kernel mode from
either idle or nohz_full userspace execution for kernels that track
context independently of RCU.
This is expected to be helpful primarily for kernels built with
CONFIG_NO_HZ_FULL=y
* tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits)
rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings
rcu: Diagnose extended sync_rcu_do_polled_gp() loops
rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings
rcutorture: Test polled expedited grace-period primitives
rcu: Add polled expedited grace-period primitives
rcutorture: Verify that polled GP API sees synchronous grace periods
rcu: Make Tiny RCU grace periods visible to polled APIs
rcu: Make polled grace-period API account for expedited grace periods
rcu: Switch polled grace-period APIs to ->gp_seq_polled
rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty
rcu/nocb: Add option to opt rcuo kthreads out of RT priority
rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread()
rcu/nocb: Add an option to offload all CPUs on boot
rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call
rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order
rcu/nocb: Add/del rdp to iterate from rcuog itself
rcu/tree: Add comment to describe GP-done condition in fqs loop
rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs()
rcu/kvfree: Remove useless monitor_todo flag
rcu: Cleanup RCU urgency state for offline CPU
...
Pull random number generator updates from Jason Donenfeld:
"Though there's been a decent amount of RNG-related development during
this last cycle, not all of it is coming through this tree, as this
cycle saw a shift toward tackling early boot time seeding issues,
which took place in other trees as well.
Here's a summary of the various patches:
- The CONFIG_ARCH_RANDOM .config option and the "nordrand" boot
option have been removed, as they overlapped with the more widely
supported and more sensible options, CONFIG_RANDOM_TRUST_CPU and
"random.trust_cpu". This change allowed simplifying a bit of arch
code.
- x86's RDRAND boot time test has been made a bit more robust, with
RDRAND disabled if it's clearly producing bogus results. This would
be a tip.git commit, technically, but I took it through random.git
to avoid a large merge conflict.
- The RNG has long since mixed in a timestamp very early in boot, on
the premise that a computer that does the same things, but does so
starting at different points in wall time, could be made to still
produce a different RNG state. Unfortunately, the clock isn't set
early in boot on all systems, so now we mix in that timestamp when
the time is actually set.
- User Mode Linux now uses the host OS's getrandom() syscall to
generate a bootloader RNG seed and later on treats getrandom() as
the platform's RDRAND-like faculty.
- The arch_get_random_{seed_,}_long() family of functions is now
arch_get_random_{seed_,}_longs(), which enables certain platforms,
such as s390, to exploit considerable performance advantages from
requesting multiple CPU random numbers at once, while at the same
time compiling down to the same code as before on platforms like
x86.
- A small cleanup changing a cmpxchg() into a try_cmpxchg(), from
Uros.
- A comment spelling fix"
More info about other random number changes that come in through various
architecture trees in the full commentary in the pull request:
https://lore.kernel.org/all/20220731232428.2219258-1-Jason@zx2c4.com/
* tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
random: correct spelling of "overwrites"
random: handle archrandom with multiple longs
um: seed rng using host OS rng
random: use try_cmpxchg in _credit_init_bits
timekeeping: contribute wall clock to rng on time change
x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu"
random: remove CONFIG_ARCH_RANDOM
Pull integrity updates from Mimi Zohar:
"Aside from the one EVM cleanup patch, all the other changes are kexec
related.
On different architectures different keyrings are used to verify the
kexec'ed kernel image signature. Here are a number of preparatory
cleanup patches and the patches themselves for making the keyrings -
builtin_trusted_keyring, .machine, .secondary_trusted_keyring, and
.platform - consistent across the different architectures"
* tag 'integrity-v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
kexec, KEYS, s390: Make use of built-in and secondary keyring for signature verification
arm64: kexec_file: use more system keyrings to verify kernel image signature
kexec, KEYS: make the code in bzImage64_verify_sig generic
kexec: clean up arch_kexec_kernel_verify_sig
kexec: drop weak attribute from functions
kexec_file: drop weak attribute from functions
evm: Use IS_ENABLED to initialize .enabled
Pull SafeSetID updates from Micah Morton:
"This contains one commit that touches common kernel code, one that
adds functionality internal to the SafeSetID LSM code, and a few other
commits that only modify the SafeSetID LSM selftest.
The commit that touches common kernel code simply adds an LSM hook in
the setgroups() syscall that mirrors what is done for the existing LSM
hooks in the setuid() and setgid() syscalls. This commit combined with
the SafeSetID-specific one allow the LSM to filter setgroups() calls
according to configured rule sets in the same way that is already done
for setuid() and setgid()"
* tag 'safesetid-6.0' of https://github.com/micah-morton/linux:
LSM: SafeSetID: add setgroups() testing to selftest
LSM: SafeSetID: Add setgroups() security policy handling
security: Add LSM hook to setgroups() syscall
LSM: SafeSetID: add GID testing to selftest
LSM: SafeSetID: selftest cleanup and prepare for GIDs
LSM: SafeSetID: fix userns bug in selftest
Pull audit updates from Paul Moore:
"Two minor audit patches: on marks a function as static, the other
removes a redundant length check"
* tag 'audit-pr-20220801' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: make is_audit_feature_set() static
audit: remove redundant data_len check
Pull execve updates from Kees Cook:
- Allow unsharing time namespace on vfork+exec (Andrei Vagin)
- Replace usage of deprecated kmap APIs (Fabio M. De Francesco)
- Fix spelling mistake (Zhang Jiaming)
* tag 'execve-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
exec: Call kmap_local_page() in copy_string_kernel()
exec: Fix a spelling mistake
selftests/timens: add a test for vfork+exit
fs/exec: allow to unshare a time namespace on vfork+exec
Pull block updates from Jens Axboe:
- Improve the type checking of request flags (Bart)
- Ensure queue mapping for a single queues always picks the right queue
(Bart)
- Sanitize the io priority handling (Jan)
- rq-qos race fix (Jinke)
- Reserved tags handling improvements (John)
- Separate memory alignment from file/disk offset aligment for O_DIRECT
(Keith)
- Add new ublk driver, userspace block driver using io_uring for
communication with the userspace backend (Ming)
- Use try_cmpxchg() to cleanup the code in various spots (Uros)
- Finally remove bdevname() (Christoph)
- Clean up the zoned device handling (Christoph)
- Clean up independent access range support (Christoph)
- Clean up and improve block sysfs handling (Christoph)
- Clean up and improve teardown of block devices.
This turns the usual two step process into something that is simpler
to implement and handle in block drivers (Christoph)
- Clean up chunk size handling (Christoph)
- Misc cleanups and fixes (Bart, Bo, Dan, GuoYong, Jason, Keith, Liu,
Ming, Sebastian, Yang, Ying)
* tag 'for-5.20/block-2022-07-29' of git://git.kernel.dk/linux-block: (178 commits)
ublk_drv: fix double shift bug
ublk_drv: make sure that correct flags(features) returned to userspace
ublk_drv: fix error handling of ublk_add_dev
ublk_drv: fix lockdep warning
block: remove __blk_get_queue
block: call blk_mq_exit_queue from disk_release for never added disks
blk-mq: fix error handling in __blk_mq_alloc_disk
ublk: defer disk allocation
ublk: rewrite ublk_ctrl_get_queue_affinity to not rely on hctx->cpumask
ublk: fold __ublk_create_dev into ublk_ctrl_add_dev
ublk: cleanup ublk_ctrl_uring_cmd
ublk: simplify ublk_ch_open and ublk_ch_release
ublk: remove the empty open and release block device operations
ublk: remove UBLK_IO_F_PREFLUSH
ublk: add a MAINTAINERS entry
block: don't allow the same type rq_qos add more than once
mmc: fix disk/queue leak in case of adding disk failure
ublk_drv: fix an IS_ERR() vs NULL check
ublk: remove UBLK_IO_F_INTEGRITY
ublk_drv: remove unneeded semicolon
...
Pull io_uring updates from Jens Axboe:
- As per (valid) complaint in the last merge window, fs/io_uring.c has
grown quite large these days. io_uring isn't really tied to fs
either, as it supports a wide variety of functionality outside of
that.
Move the code to io_uring/ and split it into files that either
implement a specific request type, and split some code into helpers
as well. The code is organized a lot better like this, and io_uring.c
is now < 4K LOC (me).
- Deprecate the epoll_ctl opcode. It'll still work, just trigger a
warning once if used. If we don't get any complaints on this, and I
don't expect any, then we can fully remove it in a future release
(me).
- Improve the cancel hash locking (Hao)
- kbuf cleanups (Hao)
- Efficiency improvements to the task_work handling (Dylan, Pavel)
- Provided buffer improvements (Dylan)
- Add support for recv/recvmsg multishot support. This is similar to
the accept (or poll) support for have for multishot, where a single
SQE can trigger everytime data is received. For applications that
expect to do more than a few receives on an instantiated socket, this
greatly improves efficiency (Dylan).
- Efficiency improvements for poll handling (Pavel)
- Poll cancelation improvements (Pavel)
- Allow specifiying a range for direct descriptor allocations (Pavel)
- Cleanup the cqe32 handling (Pavel)
- Move io_uring types to greatly cleanup the tracing (Pavel)
- Tons of great code cleanups and improvements (Pavel)
- Add a way to do sync cancelations rather than through the sqe -> cqe
interface, as that's a lot easier to use for some use cases (me).
- Add support to IORING_OP_MSG_RING for sending direct descriptors to a
different ring. This avoids the usually problematic SCM case, as we
disallow those. (me)
- Make the per-command alloc cache we use for apoll generic, place
limits on it, and use it for netmsg as well (me).
- Various cleanups (me, Michal, Gustavo, Uros)
* tag 'for-5.20/io_uring-2022-07-29' of git://git.kernel.dk/linux-block: (172 commits)
io_uring: ensure REQ_F_ISREG is set async offload
net: fix compat pointer in get_compat_msghdr()
io_uring: Don't require reinitable percpu_ref
io_uring: fix types in io_recvmsg_multishot_overflow
io_uring: Use atomic_long_try_cmpxchg in __io_account_mem
io_uring: support multishot in recvmsg
net: copy from user before calling __get_compat_msghdr
net: copy from user before calling __copy_msghdr
io_uring: support 0 length iov in buffer select in compat
io_uring: fix multishot ending when not polled
io_uring: add netmsg cache
io_uring: impose max limit on apoll cache
io_uring: add abstraction around apoll cache
io_uring: move apoll cache to poll.c
io_uring: consolidate hash_locked io-wq handling
io_uring: clear REQ_F_HASH_LOCKED on hash removal
io_uring: don't race double poll setting REQ_F_ASYNC_DATA
io_uring: don't miss setting REQ_F_DOUBLE_POLL
io_uring: disable multishot recvmsg
io_uring: only trace one of complete or overflow
...
Pull power management updates from Rafael Wysocki:
"These are mostly minor improvements all over including new CPU IDs for
the Intel RAPL driver, an Energy Model rework to use micro-Watt as the
power unit, cpufreq fixes and cleanus, cpuidle updates, devfreq
updates, documentation cleanups and a new version of the pm-graph
suite of utilities.
Specifics:
- Make cpufreq_show_cpus() more straightforward (Viresh Kumar).
- Drop unnecessary CPU hotplug locking from store() used by cpufreq
sysfs attributes (Viresh Kumar).
- Make the ACPI cpufreq driver support the boost control interface on
Zhaoxin/Centaur processors (Tony W Wang-oc).
- Print a warning message on attempts to free an active cpufreq
policy which should never happen (Viresh Kumar).
- Fix grammar in the Kconfig help text for the loongson2 cpufreq
driver (Randy Dunlap).
- Use cpumask_var_t for an on-stack CPU mask in the ondemand cpufreq
governor (Zhao Liu).
- Add trace points for guest_halt_poll_ns grow/shrink to the haltpoll
cpuidle driver (Eiichi Tsukata).
- Modify intel_idle to treat C1 and C1E as independent idle states on
Sapphire Rapids (Artem Bityutskiy).
- Extend support for wakeirq to callback wrappers used during system
suspend and resume (Ulf Hansson).
- Defer waiting for device probe before loading a hibernation image
till the first actual device access to avoid possible deadlocks
reported by syzbot (Tetsuo Handa).
- Unify device_init_wakeup() for PM_SLEEP and !PM_SLEEP (Bjorn
Helgaas).
- Add Raptor Lake-P to the list of processors supported by the Intel
RAPL driver (George D Sworo).
- Add Alder Lake-N and Raptor Lake-P to the list of processors for
which Power Limit4 is supported in the Intel RAPL driver (Sumeet
Pawnikar).
- Make pm_genpd_remove() check genpd_debugfs_dir against NULL before
attempting to remove it (Hsin-Yi Wang).
- Change the Energy Model code to represent power in micro-Watts and
adjust its users accordingly (Lukasz Luba).
- Add new devfreq driver for Mediatek CCI (Cache Coherent
Interconnect) (Johnson Wang).
- Convert the Samsung Exynos SoC Bus bindings to DT schema of
exynos-bus.c (Krzysztof Kozlowski).
- Address kernel-doc warnings by adding the description for unused
function parameters in devfreq core (Mauro Carvalho Chehab).
- Use NULL to pass a null pointer rather than zero according to the
function propotype in imx-bus.c (Colin Ian King).
- Print error message instead of error interger value in
tegra30-devfreq.c (Dmitry Osipenko).
- Add checks to prevent setting negative frequency QoS limits for
CPUs (Shivnandan Kumar).
- Update the pm-graph suite of utilities to the latest revision 5.9
including multiple improvements (Todd Brandt).
- Drop pme_interrupt reference from the PCI power management
documentation (Mario Limonciello)"
* tag 'pm-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (27 commits)
powercap: RAPL: Add Power Limit4 support for Alder Lake-N and Raptor Lake-P
PM: QoS: Add check to make sure CPU freq is non-negative
PM: hibernate: defer device probing when resuming from hibernation
intel_idle: make SPR C1 and C1E be independent
cpufreq: ondemand: Use cpumask_var_t for on-stack cpu mask
cpufreq: loongson2: fix Kconfig "its" grammar
pm-graph v5.9
cpufreq: Warn users while freeing active policy
cpufreq: scmi: Support the power scale in micro-Watts in SCMI v3.1
firmware: arm_scmi: Get detailed power scale from perf
Documentation: EM: Switch to micro-Watts scale
PM: EM: convert power field to micro-Watts precision and align drivers
PM / devfreq: tegra30: Add error message for devm_devfreq_add_device()
PM / devfreq: imx-bus: use NULL to pass a null pointer rather than zero
PM / devfreq: shut up kernel-doc warnings
dt-bindings: interconnect: samsung,exynos-bus: convert to dtschema
PM / devfreq: mediatek: Introduce MediaTek CCI devfreq driver
dt-bindings: interconnect: Add MediaTek CCI dt-bindings
PM: domains: Ensure genpd_debugfs_dir exists before remove
PM: runtime: Extend support for wakeirq for force_suspend|resume
...
Pull irq updates from Thomas Gleixner:
"Updates for interrupt core and drivers:
Core:
- Fix a few inconsistencies between UP and SMP vs interrupt
affinities
- Small updates and cleanups all over the place
New drivers:
- LoongArch interrupt controller
- Renesas RZ/G2L interrupt controller
Updates:
- Hotpath optimization for SiFive PLIC
- Workaround for broken PLIC edge triggered interrupts
- Simall cleanups and improvements as usual"
* tag 'irq-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
irqchip/mmp: Declare init functions in common header file
irqchip/mips-gic: Check the return value of ioremap() in gic_of_init()
genirq: Use for_each_action_of_desc in actions_show()
irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch
irqchip: Add LoongArch CPU interrupt controller support
irqchip: Add Loongson Extended I/O interrupt controller support
irqchip/loongson-liointc: Add ACPI init support
irqchip/loongson-pch-msi: Add ACPI init support
irqchip/loongson-pch-pic: Add ACPI init support
irqchip: Add Loongson PCH LPC controller support
LoongArch: Prepare to support multiple pch-pic and pch-msi irqdomain
LoongArch: Use ACPI_GENERIC_GSI for gsi handling
genirq/generic_chip: Export irq_unmap_generic_chip
ACPI: irq: Allow acpi_gsi_to_irq() to have an arch-specific fallback
APCI: irq: Add support for multiple GSI domains
LoongArch: Provisionally add ACPICA data structures
irqdomain: Use hwirq_max instead of revmap_size for NOMAP domains
irqdomain: Report irq number for NOMAP domains
irqchip/gic-v3: Fix comment typo
dt-bindings: interrupt-controller: renesas,rzg2l-irqc: Document RZ/V2L SoC
...
Pull perf events updates from Ingo Molnar:
- Fix Intel Alder Lake PEBS memory access latency & data source
profiling info bugs.
- Use Intel large-PEBS hardware feature in more circumstances, to
reduce PMI overhead & reduce sampling data.
- Extend the lost-sample profiling output with the PERF_FORMAT_LOST ABI
variant, which tells tooling the exact number of samples lost.
- Add new IBS register bits definitions.
- AMD uncore events: Add PerfMonV2 DF (Data Fabric) enhancements.
* tag 'perf-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/ibs: Add new IBS register bits into header
perf/x86/intel: Fix PEBS data source encoding for ADL
perf/x86/intel: Fix PEBS memory access info encoding for ADL
perf/core: Add a new read format to get a number of lost samples
perf/x86/amd/uncore: Add PerfMonV2 RDPMC assignments
perf/x86/amd/uncore: Add PerfMonV2 DF event format
perf/x86/amd/uncore: Detect available DF counters
perf/x86/amd/uncore: Use attr_update for format attributes
perf/x86/amd/uncore: Use dynamic events array
x86/events/intel/ds: Enable large PEBS for PERF_SAMPLE_WEIGHT_TYPE
Pull locking updates from Ingo Molnar:
"This was a fairly quiet cycle for the locking subsystem:
- lockdep: Fix a handful of the more complex lockdep_init_map_*()
primitives that can lose the lock_type & cause false reports. No
such mishap was observed in the wild.
- jump_label improvements: simplify the cross-arch support of initial
NOP patching by making it arch-specific code (used on MIPS only),
and remove the s390 initial NOP patching that was superfluous"
* tag 'locking-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Fix lockdep_init_map_*() confusion
jump_label: make initial NOP patching the special case
jump_label: mips: move module NOP patching into arch code
jump_label: s390: avoid pointless initial NOP patching
Pull scheduler updates from Ingo Molnar:
"Load-balancing improvements:
- Improve NUMA balancing on AMD Zen systems for affine workloads.
- Improve the handling of reduced-capacity CPUs in load-balancing.
- Energy Model improvements: fix & refine all the energy fairness
metrics (PELT), and remove the conservative threshold requiring 6%
energy savings to migrate a task. Doing this improves power
efficiency for most workloads, and also increases the reliability
of energy-efficiency scheduling.
- Optimize/tweak select_idle_cpu() to spend (much) less time
searching for an idle CPU on overloaded systems. There's reports of
several milliseconds spent there on large systems with large
workloads ...
[ Since the search logic changed, there might be behavioral side
effects. ]
- Improve NUMA imbalance behavior. On certain systems with spare
capacity, initial placement of tasks is non-deterministic, and such
an artificial placement imbalance can persist for a long time,
hurting (and sometimes helping) performance.
The fix is to make fork-time task placement consistent with runtime
NUMA balancing placement.
Note that some performance regressions were reported against this,
caused by workloads that are not memory bandwith limited, which
benefit from the artificial locality of the placement bug(s). Mel
Gorman's conclusion, with which we concur, was that consistency is
better than random workload benefits from non-deterministic bugs:
"Given there is no crystal ball and it's a tradeoff, I think
it's better to be consistent and use similar logic at both fork
time and runtime even if it doesn't have universal benefit."
- Improve core scheduling by fixing a bug in
sched_core_update_cookie() that caused unnecessary forced idling.
- Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs
for newly woken tasks.
- Fix a newidle balancing bug that introduced unnecessary wakeup
latencies.
ABI improvements/fixes:
- Do not check capabilities and do not issue capability check denial
messages when a scheduler syscall doesn't require privileges. (Such
as increasing niceness.)
- Add forced-idle accounting to cgroups too.
- Fix/improve the RSEQ ABI to not just silently accept unknown flags.
(No existing tooling is known to have learned to rely on the
previous behavior.)
- Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.
Optimizations:
- Optimize & simplify leaf_cfs_rq_list()
- Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().
Misc fixes & cleanups:
- Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.
- Fix a full-NOHZ bug that can in some cases result in the tick not
being re-enabled when the last SCHED_RT task is gone from a
runqueue but there's still SCHED_OTHER tasks around.
- Various PREEMPT_RT related fixes.
- Misc cleanups & smaller fixes"
* tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
rseq: Kill process when unknown flags are encountered in ABI structures
rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags
sched/core: Fix the bug that task won't enqueue into core tree when update cookie
nohz/full, sched/rt: Fix missed tick-reenabling bug in dequeue_task_rt()
sched/core: Always flush pending blk_plug
sched/fair: fix case with reduced capacity CPU
sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling
sched/core: add forced idle accounting for cgroups
sched/fair: Remove the energy margin in feec()
sched/fair: Remove task_util from effective utilization in feec()
sched/fair: Use the same cpumask per-PD throughout find_energy_efficient_cpu()
sched/fair: Rename select_idle_mask to select_rq_mask
sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()
sched/fair: Decay task PELT values during wakeup migration
sched/fair: Provide u64 read for 32-bits arch helper
sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
sched: only perform capability check on privileged operation
sched: Remove unused function group_first_cpu()
sched/fair: Remove redundant word " *"
selftests/rseq: check if libc rseq support is registered
...
rseq_abi()->flags and rseq_abi()->rseq_cs->flags 29 upper bits are
currently unused.
The current behavior when those bits are set is to ignore them. This is
not an ideal behavior, because when future features will start using
those flags, if user-space fails to correctly validate that the kernel
indeed supports those flags (e.g. with a new sys_rseq flags bit) before
using them, it may incorrectly assume that the kernel will handle those
flags way when in fact those will be silently ignored on older kernels.
Validating that unused flags bits are cleared will allow a smoother
transition when those flags will start to be used by allowing
applications to fail early, and obviously, when they attempt to use the
new flags on an older kernel that does not support them.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20220622194617.1155957-2-mathieu.desnoyers@efficios.com
Pull x86 fixes from Borislav Petkov:
- Update the 'mitigations=' kernel param documentation
- Check the IBPB feature flag before enabling IBPB in firmware calls
because cloud vendors' fantasy when it comes to creating guest
configurations is unlimited
- Unexport sev_es_ghcb_hv_call() before 5.19 releases now that HyperV
doesn't need it anymore
- Remove dead CONFIG_* items
* tag 'x86_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
docs/kernel-parameters: Update descriptions for "mitigations=" param with retbleed
x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available
Revert "x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV"
x86/configs: Update configs in x86_debug.config
Pull locking fix from Borislav Petkov:
- Avoid rwsem lockups in certain situations when handling the handoff
bit
* tag 'locking_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by first waiter
With commit d257cc8cb8 ("locking/rwsem: Make handoff bit handling more
consistent"), the writer that sets the handoff bit can be interrupted
out without clearing the bit if the wait queue isn't empty. This disables
reader and writer optimistic lock spinning and stealing.
Now if a non-first writer in the queue is somehow woken up or a new
waiter enters the slowpath, it can't acquire the lock. This is not the
case before commit d257cc8cb8 as the writer that set the handoff bit
will clear it when exiting out via the out_nolock path. This is less
efficient as the busy rwsem stays in an unlock state for a longer time.
In some cases, this new behavior may cause lockups as shown in [1] and
[2].
This patch allows a non-first writer to ignore the handoff bit if it
is not originally set or initiated by the first waiter. This patch is
shown to be effective in fixing the lockup problem reported in [1].
[1] https://lore.kernel.org/lkml/20220617134325.GC30825@techsingularity.net/
[2] https://lore.kernel.org/lkml/3f02975c-1a9d-be20-32cf-f1d8e3dfafcc@oracle.com/
Fixes: d257cc8cb8 ("locking/rwsem: Make handoff bit handling more consistent")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20220622200419.778799-1-longman@redhat.com
Pull workqueue fix from Tejun Heo:
"Just one commit to suppress a spurious warning added during the 5.19
cycle"
* tag 'wq-for-5.19-rc8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Avoid a false warning in unbind_workers()
Doing set_cpus_allowed_ptr() with wq_unbound_cpumask can be possible
fails and trigger the false warning.
Use cpu_possible_mask instead when wq_unbound_cpumask has no active CPUs.
It is very easy to trigger the warning:
Set wq_unbound_cpumask to a small set of CPUs.
Offline all the CPUs of wq_unbound_cpumask.
Offline an extra CPU and trigger the warning.
Fixes: 10a5a651e3 ("workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs")
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Merge devfreq changes, PM QoS change, and power management tools and
documentation changes for v5.20-rc1:
- Add new devfreq driver for Mediatek CCI (Cache Coherent
Interconnect) (Johnson Wang).
- Convert the Samsung Exynos SoC Bus bindings to DT schema of
exynos-bus.c (Krzysztof Kozlowski).
- Address kernel-doc warnings by adding the description for unused
fucntion parameters in devfreq core (Mauro Carvalho Chehab).
- Use NULL to pass a null pointer rather than zero according to the
function propotype in imx-bus.c (Colin Ian King).
- Print error message instead of error interger value in
tegra30-devfreq.c (Dmitry Osipenko).
- Add checks to prevent setting negative frequency QoS limits for
CPUs (Shivnandan Kumar).
- Update the pm-graph suite of utilities to the latest revision 5.9
including multiple improvements (Todd Brandt).
- Drop pme_interrupt reference from the PCI power management
documentation (Mario Limonciello).
* pm-devfreq:
PM / devfreq: tegra30: Add error message for devm_devfreq_add_device()
PM / devfreq: imx-bus: use NULL to pass a null pointer rather than zero
PM / devfreq: shut up kernel-doc warnings
dt-bindings: interconnect: samsung,exynos-bus: convert to dtschema
PM / devfreq: mediatek: Introduce MediaTek CCI devfreq driver
dt-bindings: interconnect: Add MediaTek CCI dt-bindings
* pm-qos:
PM: QoS: Add check to make sure CPU freq is non-negative
* pm-tools:
pm-graph v5.9
* pm-docs:
Documentation: PM: Drop pme_interrupt reference
Merge core device power management changes for v5.20-rc1:
- Extend support for wakeirq to callback wrappers used during system
suspend and resume (Ulf Hansson).
- Defer waiting for device probe before loading a hibernation image
till the first actual device access to avoid possible deadlocks
reported by syzbot (Tetsuo Handa).
- Unify device_init_wakeup() for PM_SLEEP and !PM_SLEEP (Bjorn
Helgaas).
- Add Raptor Lake-P to the list of processors supported by the Intel
RAPL driver (George D Sworo).
- Add Alder Lake-N and Raptor Lake-P to the list of processors for
which Power Limit4 is supported in the Intel RAPL driver (Sumeet
Pawnikar).
- Make pm_genpd_remove() check genpd_debugfs_dir against NULL before
attempting to remove it (Hsin-Yi Wang).
- Change the Energy Model code to represent power in micro-Watts and
adjust its users accordingly (Lukasz Luba).
* pm-core:
PM: runtime: Extend support for wakeirq for force_suspend|resume
* pm-sleep:
PM: hibernate: defer device probing when resuming from hibernation
PM: wakeup: Unify device_init_wakeup() for PM_SLEEP and !PM_SLEEP
* powercap:
powercap: RAPL: Add Power Limit4 support for Alder Lake-N and Raptor Lake-P
powercap: intel_rapl: Add support for RAPTORLAKE_P
* pm-domains:
PM: domains: Ensure genpd_debugfs_dir exists before remove
* pm-em:
cpufreq: scmi: Support the power scale in micro-Watts in SCMI v3.1
firmware: arm_scmi: Get detailed power scale from perf
Documentation: EM: Switch to micro-Watts scale
PM: EM: convert power field to micro-Watts precision and align drivers
If a watch is being added to a queue, it needs to guard against
interference from addition of a new watch, manual removal of a watch and
removal of a watch due to some other queue being destroyed.
KEYCTL_WATCH_KEY guards against this for the same {key,queue} pair by
holding the key->sem writelocked and by holding refs on both the key and
the queue - but that doesn't prevent interaction from other {key,queue}
pairs.
While add_watch_to_object() does take the spinlock on the event queue,
it doesn't take the lock on the source's watch list. The assumption was
that the caller would prevent that (say by taking key->sem) - but that
doesn't prevent interference from the destruction of another queue.
Fix this by locking the watcher list in add_watch_to_object().
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: syzbot+03d7b43290037d1f87ca@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: keyrings@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since __post_watch_notification() walks wlist->watchers with only the
RCU read lock held, we need to use RCU methods to add to the list (we
already use RCU methods to remove from the list).
Fix add_watch_to_object() to use hlist_add_head_rcu() instead of
hlist_add_head() for that list.
Fixes: c73be61ced ("pipe: Add general notification queue support")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull irqchip/genirq updates from Marc Zyngier:
* Core code update:
- Non-SMP IRQ affinity fixes, allowing UP kernel to behave similarly
to SMP ones for the purpose of interrupt affinity
- Let irq_set_chip_handler_name_locked() take a const struct irq_chip *
- Tidy-up the NOMAP irqdomain API variant
- Teach action_show() to use for_each_action_of_desc()
- Make irq_chip_request_resources_parent() allow the parent callback
to be optional
- Remove dynamic allocations from populate_parent_alloc_arg()
* New drivers:
- Merge the long awaited IRQ support for the LoongArch architecture,
with the provisional ACPICA update (to be reverted once the official
support lands)
- New Renesas RZ/G2L IRQC driver, equipped with its companion GPIO
driver
* Driver updates
- Optimise the hot path operations for the SiFive PLIC, trading the
locking for per-CPU priority masking masking operations which are
apparently faster
- Work around broken PLIC implementations that deal pretty badly with
edge-triggered interrupts. Flag two implementations as affected.
- Simplify the irq-stm32-exti driver, particularly the table that
remaps the interrupts from exti to the GIC, reducing the memory usage
- Convert the ocelot irq_chip to being immutable
- Check ioremap() return value in the MIPS GIC driver
- Move MMP driver init function declarations into the common .h
- The obligatory typo fixes
Link: https://lore.kernel.org/all/20220727192356.1860546-1-maz@kernel.org
CPU frequency should never be negative.
If some client driver calls freq_qos_update_request with a
negative value which will be very high in absolute terms,
then frequency QoS sets max CPU freq at fmax as it considers
it's absolute value but it will add plist node with negative
priority.
plist node has priority from INT_MIN (highest) to INT_MAX(lowest).
Once priority is set as negative, another client will not be able
to reduce CPU frequency.
Adding check to make sure CPU freq is non-negative will fix
this problem.
Signed-off-by: Shivnandan Kumar <quic_kshivnan@quicinc.com>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
syzbot is reporting hung task at misc_open() [1], for there is a race
window of AB-BA deadlock which involves probe_count variable. Currently
wait_for_device_probe() from snapshot_open() from misc_open() can sleep
forever with misc_mtx held if probe_count cannot become 0.
When a device is probed by hub_event() work function, probe_count is
incremented before the probe function starts, and probe_count is
decremented after the probe function completed.
There are three cases that can prevent probe_count from dropping to 0.
(a) A device being probed stopped responding (i.e. broken/malicious
hardware).
(b) A process emulating a USB device using /dev/raw-gadget interface
stopped responding for some reason.
(c) New device probe requests keeps coming in before existing device
probe requests complete.
The phenomenon syzbot is reporting is (b). A process which is holding
system_transition_mutex and misc_mtx is waiting for probe_count to become
0 inside wait_for_device_probe(), but the probe function which is called
from hub_event() work function is waiting for the processes which are
blocked at mutex_lock(&misc_mtx) to respond via /dev/raw-gadget interface.
This patch mitigates (b) by deferring wait_for_device_probe() from
snapshot_open() to snapshot_write() and snapshot_ioctl(). Please note that
the possibility of (b) remains as long as any thread which is emulating a
USB device via /dev/raw-gadget interface can be blocked by uninterruptible
blocking operations (e.g. mutex_lock()).
Please also note that (a) and (c) are not addressed. Regarding (c), we
should change the code to wait for only one device which contains the
image for resuming from hibernation. I don't know how to address (a), for
use of timeout for wait_for_device_probe() might result in loss of user
data in the image. Maybe we should require the userland to wait for the
image device before opening /dev/snapshot interface.
Link: https://syzkaller.appspot.com/bug?extid=358c9ab4c93da7b7238c [1]
Reported-by: syzbot <syzbot+358c9ab4c93da7b7238c@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+358c9ab4c93da7b7238c@syzkaller.appspotmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* irq/misc-5.20:
: .
: Misc IRQ changes for 5.20:
:
: - Let irq_set_chip_handler_name_locked() take a const struct irq_chip *
:
: - Convert the ocelot irq_chip to being immutable (depends on the above)
:
: - Tidy-up the NOMAP irqdomain API variant
:
: - Teach action_show() to use for_each_action_of_desc()
:
: - Check ioremap() return value in the MIPS GIC driver
:
: - Move MMP driver init function declarations into the common .h
:
: - The obligatory typo fixes
: .
irqchip/mmp: Declare init functions in common header file
irqchip/mips-gic: Check the return value of ioremap() in gic_of_init()
genirq: Use for_each_action_of_desc in actions_show()
irqdomain: Use hwirq_max instead of revmap_size for NOMAP domains
irqdomain: Report irq number for NOMAP domains
irqchip/gic-v3: Fix comment typo
pinctrl: ocelot: Make irq_chip immutable
genirq: Allow irq_set_chip_handler_name_locked() to take a const irq_chip
Signed-off-by: Marc Zyngier <maz@kernel.org>
In preparation for splitting io_uring up a bit, move it into its own
top level directory. It didn't really belong in fs/ anyway, as it's
not a file system only API.
This adds io_uring/ and moves the core files in there, and updates the
MAINTAINERS file for the new location.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull scheduler fix from Borislav Petkov:
"A single fix to correct a wrong BUG_ON() condition for deboosted
tasks"
* tag 'sched_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Fix BUG_ON condition for deboosted tasks
Pull RCU fix from Paul McKenney:
"This contains a pair of commits that fix 282d8998e9 ("srcu: Prevent
expedited GPs and blocking readers from consuming CPU"), which was
itself a fix to an SRCU expedited grace-period problem that could
prevent kernel live patching (KLP) from completing.
That SRCU fix for KLP introduced large (as in minutes) boot-time
delays to embedded Linux kernels running on qemu/KVM. These delays
were due to the emulation of certain MMIO operations controlling
memory layout, which were emulated with one expedited grace period per
access. Common configurations required thousands of boot-time MMIO
accesses, and thus thousands of boot-time expedited SRCU grace
periods.
In these configurations, the occasional sleeps that allowed KLP to
proceed caused excessive boot delays. These commits preserve enough
sleeps to permit KLP to proceed, but few enough that the virtual
embedded kernels still boot reasonably quickly.
This represents a regression introduced in the v5.19 merge window, and
the bug is causing significant inconvenience"
* tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
srcu: Make expedited RCU grace periods block even less frequently
srcu: Block less aggressively for expedited grace periods
Add a .kunitconfig file, which provides a default, working config for
running the KCSAN tests. Note that it needs to run on an SMP machine, so
to run under kunit_tool, the --qemu_args option should be used (on a
supported architecture, like x86_64). For example:
./tools/testing/kunit/kunit.py run --arch=x86_64 --qemu_args='-smp 8'
--kunitconfig=kernel/kcsan
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
If a CPU has interrupts disabled continuously starting before the
beginning of a given expedited RCU grace period, that CPU will not
execute that grace period's IPI handler. This will in turn mean
that the ->cpu_no_qs.b.exp field in that CPU's rcu_data structure
will continue to contain the boolean value false.
Knowing whether or not a CPU has had interrupts disabled can be helpful
when debugging an expedited RCU CPU stall warning, so this commit
adds a "D" indicator expedited RCU CPU stall warnings that signifies
that the corresponding CPU has had interrupts disabled throughout.
This capability was tested as follows:
runqemu kvm slirp nographic qemuparams="-m 4096 -smp 4" bootparams=
"isolcpus=2,3 nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1
rcutorture.stall_cpu_holdoff=30 rcutorture.stall_cpu=40
rcutorture.stall_cpu_irqsoff=1 rcutorture.stall_cpu_block=0
rcutorture.stall_no_softlockup=1" -d
The rcu_torture_stall() function ran on CPU 1, which displays the "D"
as expected given the rcutorture.stall_cpu_irqsoff=1 module parameter:
............
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks:
{ 1-...D } 26467 jiffies s: 13317 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug): l=1:0-1:0x2/.
Task dump for CPU 1:
task:rcu_torture_sta state:R running task stack: 0 pid: 76 ppid: 2 flags:0x00004008
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit dumps out state when the sync_rcu_do_polled_gp() function
loops more than expected. This is a debugging aid.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When a normal RCU CPU stall warning is encountered with the
panic_on_rcu_stall sysfs variable is set, the system panics only after
the stall warning is printed. But when an expedited RCU CPU stall
warning is encountered with the panic_on_rcu_stall sysfs variable is
set, the system panics first, thus never printing the stall warning.
This commit therefore brings the expedited stall warning into line with
the normal stall warning by printing first and panicking afterwards.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds expedited grace-period functionality to RCU's polled
grace-period API, adding start_poll_synchronize_rcu_expedited() and
cond_synchronize_rcu_expedited(), which are similar to the existing
start_poll_synchronize_rcu() and cond_synchronize_rcu() functions,
respectively.
Note that although start_poll_synchronize_rcu_expedited() can be invoked
very early, the resulting expedited grace periods are not guaranteed
to start until after workqueues are fully initialized. On the other
hand, both synchronize_rcu() and synchronize_rcu_expedited() can also
be invoked very early, and the resulting grace periods will be taken
into account as they occur.
[ paulmck: Apply feedback from Neeraj Upadhyay. ]
Link: https://lore.kernel.org/all/20220121142454.1994916-1-bfoster@redhat.com/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <bfoster@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit causes rcu_torture_writer() to use WARN_ON_ONCE() to check
that the cookie returned by the current RCU flavor's ->get_gp_state()
function (get_state_synchronize_rcu() for vanilla RCU) causes that
flavor's ->poll_gp_state function (poll_state_synchronize_rcu() for
vanilla RCU) to unconditionally return true.
Note that a pair calls to synchronous grace-period-wait functions are
used. This is necessary to account for partially overlapping normal and
expedited grace periods aligning in just the wrong way with polled API
invocations, which can cause those polled API invocations to ignore one or
the other of those partially overlapping grace periods. It is unlikely
that this sort of ignored grace period will be a problem in production,
but rcutorture can make it happen quite within a few tens of seconds.
This commit is in preparation for polled expedited grace periods.
[ paulmck: Apply feedback from Frederic Weisbecker. ]
Link: https://lore.kernel.org/all/20220121142454.1994916-1-bfoster@redhat.com/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <bfoster@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, this code could splat:
oldstate = get_state_synchronize_rcu();
synchronize_rcu_expedited();
WARN_ON_ONCE(!poll_state_synchronize_rcu(oldstate));
This situation is counter-intuitive and user-unfriendly. After all, there
really was a perfectly valid full grace period right after the call to
get_state_synchronize_rcu(), so why shouldn't poll_state_synchronize_rcu()
know about it?
This commit therefore makes the polled grace-period API aware of expedited
grace periods in addition to the normal grace periods that it is already
aware of. With this change, the above code is guaranteed not to splat.
Please note that the above code can still splat due to counter wrap on the
one hand and situations involving partially overlapping normal/expedited
grace periods on the other. On 64-bit systems, the second is of course
much more likely than the first. It is possible to modify this approach
to prevent overlapping grace periods from causing splats, but only at
the expense of greatly increasing the probability of counter wrap, as
in within milliseconds on 32-bit systems and within minutes on 64-bit
systems.
This commit is in preparation for polled expedited grace periods.
Link: https://lore.kernel.org/all/20220121142454.1994916-1-bfoster@redhat.com/
Link: https://docs.google.com/document/d/1RNKWW9jQyfjxw2E8dsXVTdvZYh0HnYeSHDKog9jhdN8/edit?usp=sharing
Cc: Brian Foster <bfoster@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Sedat Dilek noticed that I had an extraneous semicolon at the end of a
line in the previous patch.
It's harmless, but unintentional, and while compilers just treat it as
an extra empty statement, for all I know some other tooling might warn
about it. So clean it up before other people notice too ;)
Fixes: 353f7988dd ("watchqueue: make sure to serialize 'wqueue->defunct' properly")
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
In function sched_core_update_cookie(), a task will enqueue into the
core tree only when it enqueued before, that is, if an uncookied task
is cookied, it will not enqueue into the core tree until it enqueue
again, which will result in unnecessary force idle.
Here follows the scenario:
CPU x and CPU y are a pair of SMT siblings.
1. Start task a running on CPU x without sleeping, and task b and
task c running on CPU y without sleeping.
2. We create a cookie and share it to task a and task b, and then
we create another cookie and share it to task c.
3. Simpling core_forceidle_sum of task a and b from /proc/PID/sched
And we will find out that core_forceidle_sum of task a takes 30%
time of the sampling period, which shouldn't happen as task a and b
have the same cookie.
Then we migrate task a to CPU x', migrate task b and c to CPU y', where
CPU x' and CPU y' are a pair of SMT siblings, and sampling again, we
will found out that core_forceidle_sum of task a and b are almost zero.
To solve this problem, we enqueue the task into the core tree if it's
on rq.
Fixes: 6e33cad0af49("sched: Trivial core scheduling cookie management")
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1656403045-100840-2-git-send-email-CruzZhao@linux.alibaba.com
dequeue_task_rt() only decrements 'rt_rq->rt_nr_running' after having
called sched_update_tick_dependency() preventing it from re-enabling the
tick on systems that no longer have pending SCHED_RT tasks but have
multiple runnable SCHED_OTHER tasks:
dequeue_task_rt()
dequeue_rt_entity()
dequeue_rt_stack()
dequeue_top_rt_rq()
sub_nr_running() // decrements rq->nr_running
sched_update_tick_dependency()
sched_can_stop_tick() // checks rq->rt.rt_nr_running,
...
__dequeue_rt_entity()
dec_rt_tasks() // decrements rq->rt.rt_nr_running
...
Every other scheduler class performs the operation in the opposite
order, and sched_update_tick_dependency() expects the values to be
updated as such. So avoid the misbehaviour by inverting the order in
which the above operations are performed in the RT scheduler.
Fixes: 76d92ac305 ("sched: Migrate sched to use new tick dependency mask model")
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220628092259.330171-1-nsaenzju@redhat.com
