The commit:
cff9b2332a ("kernel/sched: Modify initial boot task idle setup")
has changed the semantics of what is to be considered an idle task in
such a way that the idle task of an offline CPU may not carry the
PF_IDLE flag anymore.
However RCU-tasks-trace tests the opposite assertion, still assuming
that idle tasks carry the PF_IDLE flag during their whole lifecycle.
Remove this assumption to avoid spurious warnings but keep the initial
test verifying that the idle task is the current task on any offline
CPU.
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: cff9b2332a ("kernel/sched: Modify initial boot task idle setup")
Suggested-by: Joel Fernandes <joel@joelfernandes.org>
Suggested-by: Paul E . McKenney" <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
The commit:
cff9b2332a ("kernel/sched: Modify initial boot task idle setup")
has changed the semantics of what is to be considered an idle task in
such a way that CPU boot code preceding the actual idle loop is excluded
from it.
This has however introduced new potential RCU-tasks stalls when either:
1) Grace period is started before init/0 had a chance to set PF_IDLE,
keeping it stuck in the holdout list until idle ever schedules.
2) Grace period is started when some possible CPUs have never been
online, keeping their idle tasks stuck in the holdout list until the
CPU ever boots up.
3) Similar to 1) but with secondary CPUs: Grace period is started
concurrently with secondary CPU booting, putting its idle task in
the holdout list because PF_IDLE isn't yet observed on it. It stays
then stuck in the holdout list until that CPU ever schedules. The
effect is mitigated here by the hotplug AP thread that must run to
bring the CPU up.
Fix this with handling the new semantics of PF_IDLE, keeping in mind
that it may or may not be set on an idle task. Take advantage of that to
strengthen the coverage of an RCU-tasks quiescent state within an idle
task, excluding the CPU boot code from it. Only the code running within
the idle loop is now a quiescent state, along with offline CPUs.
Fixes: cff9b2332a ("kernel/sched: Modify initial boot task idle setup")
Suggested-by: Joel Fernandes <joel@joelfernandes.org>
Suggested-by: Paul E . McKenney" <paulmck@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Export the RCU point of view as to when a CPU is considered offline
(ie: when does RCU consider that a CPU is sufficiently down in the
hotplug process to not feature any possible read side).
This will be used by RCU-tasks whose vision of an offline CPU should
reasonably match the one of RCU core.
Fixes: cff9b2332a ("kernel/sched: Modify initial boot task idle setup")
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Commit 851a723e45 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") added a kfree() call to free any user
provided affinity mask, if present. It was changed later to use
kfree_rcu() in commit 9a5418bc48 ("sched/core: Use kfree_rcu()
in do_set_cpus_allowed()") to avoid a circular locking dependency
problem.
It turns out that even kfree_rcu() isn't safe for avoiding
circular locking problem. As reported by kernel test robot,
the following circular locking dependency now exists:
&rdp->nocb_lock --> rcu_node_0 --> &rq->__lock
Solve this by breaking the rcu_node_0 --> &rq->__lock chain by moving
the resched_cpu() out from under rcu_node lock.
[peterz: heavily borrowed from Waiman's Changelog]
[paulmck: applied Z qiang feedback]
Fixes: 851a723e45 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/oe-lkp/202310302207.a25f1a30-oliver.sang@intel.com
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This pull request contains the following branches:
rcu/torture: RCU torture, locktorture and generic torture infrastructure
updates that include various fixes, cleanups and consolidations.
Among the user visible things, ftrace dumps can now be found into
their own file, and module parameters get better documented and
reported on dumps.
rcu/fixes: Generic and misc fixes all over the place. Some highlights:
* Hotplug handling has seen some light cleanups and comments.
* An RCU barrier can now be triggered through sysfs to serialize
memory stress testing and avoid OOM.
* Object information is now dumped in case of invalid callback
invocation.
* Also various SRCU issues, too hard to trigger to deserve urgent
pull requests, have been fixed.
rcu/docs: RCU documentation updates
rcu/refscale: RCU reference scalability test minor fixes and doc
improvements.
rcu/tasks: RCU tasks minor fixes
rcu/stall: Stall detection updates. Introduce RCU CPU Stall notifiers
that allows a subsystem to provide informations to help debugging.
Also cure some false positive stalls.
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Merge tag 'rcu-next-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks
Pull RCU updates from Frederic Weisbecker:
- RCU torture, locktorture and generic torture infrastructure updates
that include various fixes, cleanups and consolidations.
Among the user visible things, ftrace dumps can now be found into
their own file, and module parameters get better documented and
reported on dumps.
- Generic and misc fixes all over the place. Some highlights:
* Hotplug handling has seen some light cleanups and comments
* An RCU barrier can now be triggered through sysfs to serialize
memory stress testing and avoid OOM
* Object information is now dumped in case of invalid callback
invocation
* Also various SRCU issues, too hard to trigger to deserve urgent
pull requests, have been fixed
- RCU documentation updates
- RCU reference scalability test minor fixes and doc improvements.
- RCU tasks minor fixes
- Stall detection updates. Introduce RCU CPU Stall notifiers that
allows a subsystem to provide informations to help debugging. Also
cure some false positive stalls.
* tag 'rcu-next-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks: (56 commits)
srcu: Only accelerate on enqueue time
locktorture: Check the correct variable for allocation failure
srcu: Fix callbacks acceleration mishandling
rcu: Comment why callbacks migration can't wait for CPUHP_RCUTREE_PREP
rcu: Standardize explicit CPU-hotplug calls
rcu: Conditionally build CPU-hotplug teardown callbacks
rcu: Remove references to rcu_migrate_callbacks() from diagrams
rcu: Assume rcu_report_dead() is always called locally
rcu: Assume IRQS disabled from rcu_report_dead()
rcu: Use rcu_segcblist_segempty() instead of open coding it
rcu: kmemleak: Ignore kmemleak false positives when RCU-freeing objects
srcu: Fix srcu_struct node grpmask overflow on 64-bit systems
torture: Convert parse-console.sh to mktemp
rcutorture: Traverse possible cpu to set maxcpu in rcu_nocb_toggle()
rcutorture: Replace schedule_timeout*() 1-jiffy waits with HZ/20
torture: Add kvm.sh --debug-info argument
locktorture: Rename readers_bind/writers_bind to bind_readers/bind_writers
doc: Catch-up update for locktorture module parameters
locktorture: Add call_rcu_chains module parameter
locktorture: Add new module parameters to lock_torture_print_module_parms()
...
This series adds a kernel boot parameter that causes the kernel to
panic if one of the call_smp_function() APIs is stalled for more than
the specified duration. This is useful in deployments in which a clean
panic is preferable to an indefinite stall.
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Merge tag 'csd-lock.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull CSD lock update from Paul McKenney:
"This adds a kernel boot parameter that causes the kernel to panic if
one of the call_smp_function() APIs is stalled for more than the
specified duration.
This is useful in deployments in which a clean panic is preferable to
an indefinite stall"
* tag 'csd-lock.2023.10.23a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
smp,csd: Throw an error if a CSD lock is stuck for too long
- Limit the hardcoded topology quirk for Hygon CPUs to those which have a
model ID less than 4. The newer models have the topology CPUID leaf 0xB
correctly implemented and are not affected.
- Make SMT control more robust against enumeration failures
SMT control was added to allow controlling SMT at boottime or
runtime. The primary purpose was to provide a simple mechanism to
disable SMT in the light of speculation attack vectors.
It turned out that the code is sensible to enumeration failures and
worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
which means the primary thread mask is not set up correctly. By chance
a XEN/PV boot ends up with smp_num_siblings == 2, which makes the
hotplug control stay at its default value "enabled". So the mask is
never evaluated.
The ongoing rework of the topology evaluation caused XEN/PV to end up
with smp_num_siblings == 1, which sets the SMT control to "not
supported" and the empty primary thread mask causes the hotplug core to
deny the bringup of the APS.
Make the decision logic more robust and take 'not supported' and 'not
implemented' into account for the decision whether a CPU should be
booted or not.
- Fake primary thread mask for XEN/PV
Pretend that all XEN/PV vCPUs are primary threads, which makes the
usage of the primary thread mask valid on XEN/PV. That is consistent
with because all of the topology information on XEN/PV is fake or even
non-existent.
- Encapsulate topology information in cpuinfo_x86
Move the randomly scattered topology data into a separate data
structure for readability and as a preparatory step for the topology
evaluation overhaul.
- Consolidate APIC ID data type to u32
It's fixed width hardware data and not randomly u16, int, unsigned long
or whatever developers decided to use.
- Cure the abuse of cpuinfo for persisting logical IDs.
Per CPU cpuinfo is used to persist the logical package and die
IDs. That's really not the right place simply because cpuinfo is
subject to be reinitialized when a CPU goes through an offline/online
cycle.
Use separate per CPU data for the persisting to enable the further
topology management rework. It will be removed once the new topology
management is in place.
- Provide a debug interface for inspecting topology information
Useful in general and extremly helpful for validating the topology
management rework in terms of correctness or "bug" compatibility.
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Merge tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Thomas Gleixner:
- Limit the hardcoded topology quirk for Hygon CPUs to those which have
a model ID less than 4.
The newer models have the topology CPUID leaf 0xB correctly
implemented and are not affected.
- Make SMT control more robust against enumeration failures
SMT control was added to allow controlling SMT at boottime or
runtime. The primary purpose was to provide a simple mechanism to
disable SMT in the light of speculation attack vectors.
It turned out that the code is sensible to enumeration failures and
worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
which means the primary thread mask is not set up correctly. By
chance a XEN/PV boot ends up with smp_num_siblings == 2, which makes
the hotplug control stay at its default value "enabled". So the mask
is never evaluated.
The ongoing rework of the topology evaluation caused XEN/PV to end up
with smp_num_siblings == 1, which sets the SMT control to "not
supported" and the empty primary thread mask causes the hotplug core
to deny the bringup of the APS.
Make the decision logic more robust and take 'not supported' and 'not
implemented' into account for the decision whether a CPU should be
booted or not.
- Fake primary thread mask for XEN/PV
Pretend that all XEN/PV vCPUs are primary threads, which makes the
usage of the primary thread mask valid on XEN/PV. That is consistent
with because all of the topology information on XEN/PV is fake or
even non-existent.
- Encapsulate topology information in cpuinfo_x86
Move the randomly scattered topology data into a separate data
structure for readability and as a preparatory step for the topology
evaluation overhaul.
- Consolidate APIC ID data type to u32
It's fixed width hardware data and not randomly u16, int, unsigned
long or whatever developers decided to use.
- Cure the abuse of cpuinfo for persisting logical IDs.
Per CPU cpuinfo is used to persist the logical package and die IDs.
That's really not the right place simply because cpuinfo is subject
to be reinitialized when a CPU goes through an offline/online cycle.
Use separate per CPU data for the persisting to enable the further
topology management rework. It will be removed once the new topology
management is in place.
- Provide a debug interface for inspecting topology information
Useful in general and extremly helpful for validating the topology
management rework in terms of correctness or "bug" compatibility.
* tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
x86/apic, x86/hyperv: Use u32 in hv_snp_boot_ap() too
x86/cpu: Provide debug interface
x86/cpu/topology: Cure the abuse of cpuinfo for persisting logical ids
x86/apic: Use u32 for wakeup_secondary_cpu[_64]()
x86/apic: Use u32 for [gs]et_apic_id()
x86/apic: Use u32 for phys_pkg_id()
x86/apic: Use u32 for cpu_present_to_apicid()
x86/apic: Use u32 for check_apicid_used()
x86/apic: Use u32 for APIC IDs in global data
x86/apic: Use BAD_APICID consistently
x86/cpu: Move cpu_l[l2]c_id into topology info
x86/cpu: Move logical package and die IDs into topology info
x86/cpu: Remove pointless evaluation of x86_coreid_bits
x86/cpu: Move cu_id into topology info
x86/cpu: Move cpu_core_id into topology info
hwmon: (fam15h_power) Use topology_core_id()
scsi: lpfc: Use topology_core_id()
x86/cpu: Move cpu_die_id into topology info
x86/cpu: Move phys_proc_id into topology info
x86/cpu: Encapsulate topology information in cpuinfo_x86
...
- Make the quirk for non-maskable MSI interrupts in the affinity setter
functional again.
It was broken by a MSI core code update, which restructured the code in
a way that the quirk flag was not longer set correctly.
Trying to restore the core logic caused a deeper inspection and it
turned out that the extra quirk flag is not required at all because
it's the inverse of the reservation mode bit, which only can be set
when the MSI interrupt is maskable.
So the trivial fix is to use the reservation mode check in the affinity
setter function and remove almost 40 lines of code related to the
no-mask quirk flag.
- Cure a Kconfig dependency issue which causes compile fails by correcting
the conditionals in the affected heaer files.
- Clean up coding style in the UV APIC driver.
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Merge tag 'x86-apic-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 APIC updates from Thomas Gleixner:
- Make the quirk for non-maskable MSI interrupts in the affinity setter
functional again.
It was broken by a MSI core code update, which restructured the code
in a way that the quirk flag was not longer set correctly.
Trying to restore the core logic caused a deeper inspection and it
turned out that the extra quirk flag is not required at all because
it's the inverse of the reservation mode bit, which only can be set
when the MSI interrupt is maskable.
So the trivial fix is to use the reservation mode check in the
affinity setter function and remove almost 40 lines of code related
to the no-mask quirk flag.
- Cure a Kconfig dependency issue which causes compile failures by
correcting the conditionals in the affected header files.
- Clean up coding style in the UV APIC driver.
* tag 'x86-apic-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/apic/msi: Fix misconfigured non-maskable MSI quirk
x86/msi: Fix compile error caused by CONFIG_GENERIC_MSI_IRQ=y && !CONFIG_X86_LOCAL_APIC
x86/platform/uv/apic: Clean up inconsistent indenting
Core:
- Avoid superfluous deactivation of the tick in the low resolution tick
NOHZ interrupt handler as the deactivation is handled already in the
idle loop and on interrupt exit.
- Update stale comments in the tick NOHZ code and rename the tick
handler functions to be self-explanatory.
- Remove an unused function in the tick NOHZ code, which was forgotten
when the last user went away.
- Handle RTC alarms which exceed the maximum alarm time of the
underlying RTC hardware gracefully.
Setting RTC alarms which exceed the maximum alarm time of the RTC
hardware failed so far and caused suspend operations to abort.
Cure this by limiting the alarm to the maximum alarm time of the RTC
hardware, which is provided by the driver. This causes early resume
wakeups, but that's way better than not suspending at all.
Drivers:
- Add a proper clocksource/event driver for the ancient Cirrus Logic
EP93xx SoC family, which is one of the last non device-tree holdouts
in arch/arm.
- The usual boring device tree bindings updates and small fixes and
enhancements all over the place.
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Merge tag 'timers-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Updates for time, timekeeping and timers:
Core:
- Avoid superfluous deactivation of the tick in the low resolution
tick NOHZ interrupt handler as the deactivation is handled already
in the idle loop and on interrupt exit.
- Update stale comments in the tick NOHZ code and rename the tick
handler functions to be self-explanatory.
- Remove an unused function in the tick NOHZ code, which was
forgotten when the last user went away.
- Handle RTC alarms which exceed the maximum alarm time of the
underlying RTC hardware gracefully.
Setting RTC alarms which exceed the maximum alarm time of the RTC
hardware failed so far and caused suspend operations to abort.
Cure this by limiting the alarm to the maximum alarm time of the
RTC hardware, which is provided by the driver. This causes early
resume wakeups, but that's way better than not suspending at all.
Drivers:
- Add a proper clocksource/event driver for the ancient Cirrus Logic
EP93xx SoC family, which is one of the last non device-tree
holdouts in arch/arm.
- The usual boring device tree bindings updates and small fixes and
enhancements all over the place"
* tag 'timers-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource: ep93xx: Add driver for Cirrus Logic EP93xx
dt-bindings: timers: Add Cirrus EP93xx
clocksource/drivers/timer-atmel-tcb: Fix initialization on SAM9 hardware
clocksource/timer-riscv: ACPI: Add timer_cannot_wakeup_cpu
clocksource/drivers/sun5i: Remove surplus dev_err() when using platform_get_irq()
drivers/clocksource/timer-ti-dm: Don't call clk_get_rate() in stop function
clocksource/drivers/timer-imx-gpt: Fix potential memory leak
dt-bindings: timer: renesas,rz-mtu3: Document RZ/{G2UL,Five} SoCs
dt-bindings: timer: renesas,rz-mtu3: Improve documentation
dt-bindings: timer: renesas,rz-mtu3: Fix overflow/underflow interrupt names
alarmtimer: Use maximum alarm time for suspend
rtc: Add API function to return alarm time bound by hardware limit
tick/nohz: Update comments some more
tick/nohz: Remove unused tick_nohz_idle_stop_tick_protected()
tick/nohz: Don't shutdown the lowres tick from itself
tick/nohz: Update obsolete comments
tick/nohz: Rename the tick handlers to more self-explanatory names
- Switch the smp_call_function*() @csd argument to call_single_data_t
type, which is a cache-line aligned typedef of the underlying struct
__call_single_data.
This ensures that the call data is not crossing a cacheline which
avoids bouncing an extra cache-line for the SMP function call
- Prevent offlining of the last housekeeping CPU when CPU isolation is
active.
Offlining the last housekeeping CPU makes no sense in general, but also
caused the scheduler to panic due to the empty CPU mask when rebuilding
the scheduler domains.
- Remove an unused CPU hotplug state
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Merge tag 'smp-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP and CPU hotplug updates from Thomas Gleixner:
- Switch the smp_call_function*() @csd argument to call_single_data_t
type, which is a cache-line aligned typedef of the underlying struct
__call_single_data.
This ensures that the call data is not crossing a cacheline which
avoids bouncing an extra cache-line for the SMP function call
- Prevent offlining of the last housekeeping CPU when CPU isolation is
active.
Offlining the last housekeeping CPU makes no sense in general, but
also caused the scheduler to panic due to the empty CPU mask when
rebuilding the scheduler domains.
- Remove an unused CPU hotplug state
* tag 'smp-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Don't offline the last non-isolated CPU
cpu/hotplug: Remove unused cpuhp_state CPUHP_AP_X86_VDSO_VMA_ONLINE
smp: Change function signatures to use call_single_data_t
Core:
- Exclude managed interrupts in the calculation of interrupts which are
targeted to a CPU which is about to be offlined to ensure that there
are enough free vectors on the still online CPUs to migrate them over.
Managed interrupts do not need to be accounted because they are
either shut down on offline or migrated to an already reserved and
guaranteed slot on a still online CPU in the interrupts affinity
mask.
Including managed interrupts is overaccounting and can result in
needlessly aborting hibernation on large server machines.
- The usual set of small improvements
Drivers:
- Make the generic interrupt chip implementation handle interrupt
domains correctly and initialize the name pointers correctly
- Add interrupt affinity setting support to the Renesas RZG2L chip
driver.
- Prevent registering syscore operations multiple times in the SiFive
PLIC chip driver.
- Update device tree handling in the NXP Layerscape MSI chip driver
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Merge tag 'irq-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq updates from Thomas Gleixner:
"Core:
- Exclude managed interrupts in the calculation of interrupts which
are targeted to a CPU which is about to be offlined to ensure that
there are enough free vectors on the still online CPUs to migrate
them over.
Managed interrupts do not need to be accounted because they are
either shut down on offline or migrated to an already reserved and
guaranteed slot on a still online CPU in the interrupts affinity
mask.
Including managed interrupts is overaccounting and can result in
needlessly aborting hibernation on large server machines.
- The usual set of small improvements
Drivers:
- Make the generic interrupt chip implementation handle interrupt
domains correctly and initialize the name pointers correctly
- Add interrupt affinity setting support to the Renesas RZG2L chip
driver.
- Prevent registering syscore operations multiple times in the SiFive
PLIC chip driver.
- Update device tree handling in the NXP Layerscape MSI chip driver"
* tag 'irq-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/sifive-plic: Fix syscore registration for multi-socket systems
irqchip/ls-scfg-msi: Use device_get_match_data()
genirq/generic_chip: Make irq_remove_generic_chip() irqdomain aware
genirq/matrix: Exclude managed interrupts in irq_matrix_allocated()
PCI/MSI: Provide stubs for IMS functions
irqchip/renesas-rzg2l: Enhance driver to support interrupt affinity setting
genirq/generic-chip: Fix the irq_chip name for /proc/interrupts
irqdomain: Annotate struct irq_domain with __counted_by
- Add a comment to explain that the preempt_disable() before unlocking
tasklist lock is not a correctness problem and just avoids the tracer
to preempt the tracee before the tracee schedules out.
- Make that preempt_disable() conditional on PREEMPT_RT=n.
RT enabled kernels cannot disable preemption at this point because
cgroup_enter_frozen() and sched_submit_work() acquire spinlocks or
rwlocks which are substituted by sleeping locks on RT. Acquiring a
sleeping lock in a preemption disable region is obviously not possible.
This obviously brings back the potential slowdown of ptrace() for RT
enabled kernels, but that's a price to be payed for latency guarantees.
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Merge tag 'core-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core updates from Thomas Gleixner:
"Two small updates to ptrace_stop():
- Add a comment to explain that the preempt_disable() before
unlocking tasklist lock is not a correctness problem and just
avoids the tracer to preempt the tracee before the tracee schedules
out.
- Make that preempt_disable() conditional on PREEMPT_RT=n.
RT enabled kernels cannot disable preemption at this point because
cgroup_enter_frozen() and sched_submit_work() acquire spinlocks or
rwlocks which are substituted by sleeping locks on RT. Acquiring a
sleeping lock in a preemption disable region is obviously not
possible.
This obviously brings back the potential slowdown of ptrace() for
RT enabled kernels, but that's a price to be paid for latency
guarantees"
* tag 'core-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
signal: Don't disable preemption in ptrace_stop() on PREEMPT_RT
signal: Add a proper comment about preempt_disable() in ptrace_stop()
- Add AMD Unified Memory Controller (UMC) events introduced with Zen 4
- Simplify & clean up the uncore management code
- Fall back from RDPMC to RDMSR on certain uncore PMUs
- Improve per-package and cstate event reading
- Extend the Intel ref-cycles event to GP counters
- Fix Intel MTL event constraints
- Improve the Intel hybrid CPU handling code
- Micro-optimize the RAPL code
- Optimize perf_cgroup_switch()
- Improve large AUX area error handling
- Misc fixes and cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull performance event updates from Ingo Molnar:
- Add AMD Unified Memory Controller (UMC) events introduced with Zen 4
- Simplify & clean up the uncore management code
- Fall back from RDPMC to RDMSR on certain uncore PMUs
- Improve per-package and cstate event reading
- Extend the Intel ref-cycles event to GP counters
- Fix Intel MTL event constraints
- Improve the Intel hybrid CPU handling code
- Micro-optimize the RAPL code
- Optimize perf_cgroup_switch()
- Improve large AUX area error handling
- Misc fixes and cleanups
* tag 'perf-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
perf/x86/amd/uncore: Pass through error code for initialization failures, instead of -ENODEV
perf/x86/amd/uncore: Fix uninitialized return value in amd_uncore_init()
x86/cpu: Fix the AMD Fam 17h, Fam 19h, Zen2 and Zen4 MSR enumerations
perf: Optimize perf_cgroup_switch()
perf/x86/amd/uncore: Add memory controller support
perf/x86/amd/uncore: Add group exclusivity
perf/x86/amd/uncore: Use rdmsr if rdpmc is unavailable
perf/x86/amd/uncore: Move discovery and registration
perf/x86/amd/uncore: Refactor uncore management
perf/core: Allow reading package events from perf_event_read_local
perf/x86/cstate: Allow reading the package statistics from local CPU
perf/x86/intel/pt: Fix kernel-doc comments
perf/x86/rapl: Annotate 'struct rapl_pmus' with __counted_by
perf/core: Rename perf_proc_update_handler() -> perf_event_max_sample_rate_handler(), for readability
perf/x86/rapl: Fix "Using plain integer as NULL pointer" Sparse warning
perf/x86/rapl: Use local64_try_cmpxchg in rapl_event_update()
perf/x86/rapl: Stop doing cpu_relax() in the local64_cmpxchg() loop in rapl_event_update()
perf/core: Bail out early if the request AUX area is out of bound
perf/x86/intel: Extend the ref-cycles event to GP counters
perf/x86/intel: Fix broken fixed event constraints extension
...
- Fair scheduler (SCHED_OTHER) improvements:
- Remove the old and now unused SIS_PROP code & option
- Scan cluster before LLC in the wake-up path
- Use candidate prev/recent_used CPU if scanning failed for cluster wakeup
- NUMA scheduling improvements:
- Improve the VMA access-PID code to better skip/scan VMAs
- Extend tracing to cover VMA-skipping decisions
- Improve/fix the recently introduced sched_numa_find_nth_cpu() code
- Generalize numa_map_to_online_node()
- Energy scheduling improvements:
- Remove the EM_MAX_COMPLEXITY limit
- Add tracepoints to track energy computation
- Make the behavior of the 'sched_energy_aware' sysctl more consistent
- Consolidate and clean up access to a CPU's max compute capacity
- Fix uclamp code corner cases
- RT scheduling improvements:
- Drive dl_rq->overloaded with dl_rq->pushable_dl_tasks updates
- Drive the ->rto_mask with rt_rq->pushable_tasks updates
- Scheduler scalability improvements:
- Rate-limit updates to tg->load_avg
- On x86 disable IBRS when CPU is offline to improve single-threaded performance
- Micro-optimize in_task() and in_interrupt()
- Micro-optimize the PSI code
- Avoid updating PSI triggers and ->rtpoll_total when there are no state changes
- Core scheduler infrastructure improvements:
- Use saved_state to reduce some spurious freezer wakeups
- Bring in a handful of fast-headers improvements to scheduler headers
- Make the scheduler UAPI headers more widely usable by user-space
- Simplify the control flow of scheduler syscalls by using lock guards
- Fix sched_setaffinity() vs. CPU hotplug race
- Scheduler debuggability improvements:
- Disallow writing invalid values to sched_rt_period_us
- Fix a race in the rq-clock debugging code triggering warnings
- Fix a warning in the bandwidth distribution code
- Micro-optimize in_atomic_preempt_off() checks
- Enforce that the tasklist_lock is held in for_each_thread()
- Print the TGID in sched_show_task()
- Remove the /proc/sys/kernel/sched_child_runs_first sysctl
- Misc cleanups & fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Fair scheduler (SCHED_OTHER) improvements:
- Remove the old and now unused SIS_PROP code & option
- Scan cluster before LLC in the wake-up path
- Use candidate prev/recent_used CPU if scanning failed for cluster
wakeup
NUMA scheduling improvements:
- Improve the VMA access-PID code to better skip/scan VMAs
- Extend tracing to cover VMA-skipping decisions
- Improve/fix the recently introduced sched_numa_find_nth_cpu() code
- Generalize numa_map_to_online_node()
Energy scheduling improvements:
- Remove the EM_MAX_COMPLEXITY limit
- Add tracepoints to track energy computation
- Make the behavior of the 'sched_energy_aware' sysctl more
consistent
- Consolidate and clean up access to a CPU's max compute capacity
- Fix uclamp code corner cases
RT scheduling improvements:
- Drive dl_rq->overloaded with dl_rq->pushable_dl_tasks updates
- Drive the ->rto_mask with rt_rq->pushable_tasks updates
Scheduler scalability improvements:
- Rate-limit updates to tg->load_avg
- On x86 disable IBRS when CPU is offline to improve single-threaded
performance
- Micro-optimize in_task() and in_interrupt()
- Micro-optimize the PSI code
- Avoid updating PSI triggers and ->rtpoll_total when there are no
state changes
Core scheduler infrastructure improvements:
- Use saved_state to reduce some spurious freezer wakeups
- Bring in a handful of fast-headers improvements to scheduler
headers
- Make the scheduler UAPI headers more widely usable by user-space
- Simplify the control flow of scheduler syscalls by using lock
guards
- Fix sched_setaffinity() vs. CPU hotplug race
Scheduler debuggability improvements:
- Disallow writing invalid values to sched_rt_period_us
- Fix a race in the rq-clock debugging code triggering warnings
- Fix a warning in the bandwidth distribution code
- Micro-optimize in_atomic_preempt_off() checks
- Enforce that the tasklist_lock is held in for_each_thread()
- Print the TGID in sched_show_task()
- Remove the /proc/sys/kernel/sched_child_runs_first sysctl
... and misc cleanups & fixes"
* tag 'sched-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits)
sched/fair: Remove SIS_PROP
sched/fair: Use candidate prev/recent_used CPU if scanning failed for cluster wakeup
sched/fair: Scan cluster before scanning LLC in wake-up path
sched: Add cpus_share_resources API
sched/core: Fix RQCF_ACT_SKIP leak
sched/fair: Remove unused 'curr' argument from pick_next_entity()
sched/nohz: Update comments about NEWILB_KICK
sched/fair: Remove duplicate #include
sched/psi: Update poll => rtpoll in relevant comments
sched: Make PELT acronym definition searchable
sched: Fix stop_one_cpu_nowait() vs hotplug
sched/psi: Bail out early from irq time accounting
sched/topology: Rename 'DIE' domain to 'PKG'
sched/psi: Delete the 'update_total' function parameter from update_triggers()
sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state changes
sched/headers: Remove comment referring to rq::cpu_load, since this has been removed
sched/numa: Complete scanning of inactive VMAs when there is no alternative
sched/numa: Complete scanning of partial VMAs regardless of PID activity
sched/numa: Move up the access pid reset logic
sched/numa: Trace decisions related to skipping VMAs
...
- Futex improvements:
- Add the 'futex2' syscall ABI, which is an attempt to get away from the
multiplex syscall and adds a little room for extentions, while lifting
some limitations.
- Fix futex PI recursive rt_mutex waiter state bug
- Fix inter-process shared futexes on no-MMU systems
- Use folios instead of pages
- Micro-optimizations of locking primitives:
- Improve arch_spin_value_unlocked() on asm-generic ticket spinlock
architectures, to improve lockref code generation.
- Improve the x86-32 lockref_get_not_zero() main loop by adding
build-time CMPXCHG8B support detection for the relevant lockref code,
and by better interfacing the CMPXCHG8B assembly code with the compiler.
- Introduce arch_sync_try_cmpxchg() on x86 to improve sync_try_cmpxchg()
code generation. Convert some sync_cmpxchg() users to sync_try_cmpxchg().
- Micro-optimize rcuref_put_slowpath()
- Locking debuggability improvements:
- Improve CONFIG_DEBUG_RT_MUTEXES=y to have a fast-path as well
- Enforce atomicity of sched_submit_work(), which is de-facto atomic but
was un-enforced previously.
- Extend <linux/cleanup.h>'s no_free_ptr() with __must_check semantics
- Fix ww_mutex self-tests
- Clean up const-propagation in <linux/seqlock.h> and simplify
the API-instantiation macros a bit.
- RT locking improvements:
- Provide the rt_mutex_*_schedule() primitives/helpers and use them
in the rtmutex code to avoid recursion vs. rtlock on the PI state.
- Add nested blocking lockdep asserts to rt_mutex_lock(), rtlock_lock()
and rwbase_read_lock().
- Plus misc fixes & cleanups
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Info Molnar:
"Futex improvements:
- Add the 'futex2' syscall ABI, which is an attempt to get away from
the multiplex syscall and adds a little room for extentions, while
lifting some limitations.
- Fix futex PI recursive rt_mutex waiter state bug
- Fix inter-process shared futexes on no-MMU systems
- Use folios instead of pages
Micro-optimizations of locking primitives:
- Improve arch_spin_value_unlocked() on asm-generic ticket spinlock
architectures, to improve lockref code generation
- Improve the x86-32 lockref_get_not_zero() main loop by adding
build-time CMPXCHG8B support detection for the relevant lockref
code, and by better interfacing the CMPXCHG8B assembly code with
the compiler
- Introduce arch_sync_try_cmpxchg() on x86 to improve
sync_try_cmpxchg() code generation. Convert some sync_cmpxchg()
users to sync_try_cmpxchg().
- Micro-optimize rcuref_put_slowpath()
Locking debuggability improvements:
- Improve CONFIG_DEBUG_RT_MUTEXES=y to have a fast-path as well
- Enforce atomicity of sched_submit_work(), which is de-facto atomic
but was un-enforced previously.
- Extend <linux/cleanup.h>'s no_free_ptr() with __must_check
semantics
- Fix ww_mutex self-tests
- Clean up const-propagation in <linux/seqlock.h> and simplify the
API-instantiation macros a bit
RT locking improvements:
- Provide the rt_mutex_*_schedule() primitives/helpers and use them
in the rtmutex code to avoid recursion vs. rtlock on the PI state.
- Add nested blocking lockdep asserts to rt_mutex_lock(),
rtlock_lock() and rwbase_read_lock()
.. plus misc fixes & cleanups"
* tag 'locking-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
futex: Don't include process MM in futex key on no-MMU
locking/seqlock: Fix grammar in comment
alpha: Fix up new futex syscall numbers
locking/seqlock: Propagate 'const' pointers within read-only methods, remove forced type casts
locking/lockdep: Fix string sizing bug that triggers a format-truncation compiler-warning
locking/seqlock: Change __seqprop() to return the function pointer
locking/seqlock: Simplify SEQCOUNT_LOCKNAME()
locking/atomics: Use atomic_try_cmpxchg_release() to micro-optimize rcuref_put_slowpath()
locking/atomic, xen: Use sync_try_cmpxchg() instead of sync_cmpxchg()
locking/atomic/x86: Introduce arch_sync_try_cmpxchg()
locking/atomic: Add generic support for sync_try_cmpxchg() and its fallback
locking/seqlock: Fix typo in comment
futex/requeue: Remove unnecessary ‘NULL’ initialization from futex_proxy_trylock_atomic()
locking/local, arch: Rewrite local_add_unless() as a static inline function
locking/debug: Fix debugfs API return value checks to use IS_ERR()
locking/ww_mutex/test: Make sure we bail out instead of livelock
locking/ww_mutex/test: Fix potential workqueue corruption
locking/ww_mutex/test: Use prng instead of rng to avoid hangs at bootup
futex: Add sys_futex_requeue()
futex: Add flags2 argument to futex_requeue()
...
Here's the bcachefs filesystem pull request.
One new patch since last week: the exportfs constants ended up
conflicting with other filesystems that are also getting added to the
global enum, so switched to new constants picked by Amir.
I'll also be sending another pull request later on in the cycle bringing
things up to date my master branch that people are currently running;
that will be restricted to fs/bcachefs/, naturally.
Testing - fstests as well as the bcachefs specific tests in ktest:
https://evilpiepirate.org/~testdashboard/ci?branch=bcachefs-for-upstream
It's also been soaking in linux-next, which resulted in a whole bunch of
smatch complaints and fixes and a patch or two from Kees.
The only new non fs/bcachefs/ patch is the objtool patch that adds
bcachefs functions to the list of noreturns. The patch that exports
osq_lock() has been dropped for now, per Ingo.
Prereq patch list:
faf1dce852 objtool: Add bcachefs noreturns
73badee428 lib/generic-radix-tree.c: Add peek_prev()
9492261ff2 lib/generic-radix-tree.c: Don't overflow in peek()
0fb5d567f5 MAINTAINERS: Add entry for generic-radix-tree
b414e8ecd4 closures: Add a missing include
48b7935722 closures: closure_nr_remaining()
ced58fc7ab closures: closure_wait_event()
bd0d22e41e MAINTAINERS: Add entry for closures
8c8d2d9670 bcache: move closures to lib/
957e48087d locking: export contention tracepoints for bcachefs six locks
21db931445 lib: Export errname
83feeb1955 lib/string_helpers: string_get_size() now returns characters wrote
7d672f4094 stacktrace: Export stack_trace_save_tsk
771eb4fe8b fs: factor out d_mark_tmpfile()
2b69987be5 sched: Add task_struct->faults_disabled_mapping
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Merge tag 'bcachefs-2023-10-30' of https://evilpiepirate.org/git/bcachefs
Pull initial bcachefs updates from Kent Overstreet:
"Here's the bcachefs filesystem pull request.
One new patch since last week: the exportfs constants ended up
conflicting with other filesystems that are also getting added to the
global enum, so switched to new constants picked by Amir.
The only new non fs/bcachefs/ patch is the objtool patch that adds
bcachefs functions to the list of noreturns. The patch that exports
osq_lock() has been dropped for now, per Ingo"
* tag 'bcachefs-2023-10-30' of https://evilpiepirate.org/git/bcachefs: (2781 commits)
exportfs: Change bcachefs fid_type enum to avoid conflicts
bcachefs: Refactor memcpy into direct assignment
bcachefs: Fix drop_alloc_keys()
bcachefs: snapshot_create_lock
bcachefs: Fix snapshot skiplists during snapshot deletion
bcachefs: bch2_sb_field_get() refactoring
bcachefs: KEY_TYPE_error now counts towards i_sectors
bcachefs: Fix handling of unknown bkey types
bcachefs: Switch to unsafe_memcpy() in a few places
bcachefs: Use struct_size()
bcachefs: Correctly initialize new buckets on device resize
bcachefs: Fix another smatch complaint
bcachefs: Use strsep() in split_devs()
bcachefs: Add iops fields to bch_member
bcachefs: Rename bch_sb_field_members -> bch_sb_field_members_v1
bcachefs: New superblock section members_v2
bcachefs: Add new helper to retrieve bch_member from sb
bcachefs: bucket_lock() is now a sleepable lock
bcachefs: fix crc32c checksum merge byte order problem
bcachefs: Fix bch2_inode_delete_keys()
...
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Merge tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode time accessor updates from Christian Brauner:
"This finishes the conversion of all inode time fields to accessor
functions as discussed on list. Changing timestamps manually as we
used to do before is error prone. Using accessors function makes this
robust.
It does not contain the switch of the time fields to discrete 64 bit
integers to replace struct timespec and free up space in struct inode.
But after this, the switch can be trivially made and the patch should
only affect the vfs if we decide to do it"
* tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (86 commits)
fs: rename inode i_atime and i_mtime fields
security: convert to new timestamp accessors
selinux: convert to new timestamp accessors
apparmor: convert to new timestamp accessors
sunrpc: convert to new timestamp accessors
mm: convert to new timestamp accessors
bpf: convert to new timestamp accessors
ipc: convert to new timestamp accessors
linux: convert to new timestamp accessors
zonefs: convert to new timestamp accessors
xfs: convert to new timestamp accessors
vboxsf: convert to new timestamp accessors
ufs: convert to new timestamp accessors
udf: convert to new timestamp accessors
ubifs: convert to new timestamp accessors
tracefs: convert to new timestamp accessors
sysv: convert to new timestamp accessors
squashfs: convert to new timestamp accessors
server: convert to new timestamp accessors
client: convert to new timestamp accessors
...
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Merge tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual miscellaneous features, cleanups, and fixes
for vfs and individual fses.
Features:
- Rename and export helpers that get write access to a mount. They
are used in overlayfs to get write access to the upper mount.
- Print the pretty name of the root device on boot failure. This
helps in scenarios where we would usually only print
"unknown-block(1,2)".
- Add an internal SB_I_NOUMASK flag. This is another part in the
endless POSIX ACL saga in a way.
When POSIX ACLs are enabled via SB_POSIXACL the vfs cannot strip
the umask because if the relevant inode has POSIX ACLs set it might
take the umask from there. But if the inode doesn't have any POSIX
ACLs set then we apply the umask in the filesytem itself. So we end
up with:
(1) no SB_POSIXACL -> strip umask in vfs
(2) SB_POSIXACL -> strip umask in filesystem
The umask semantics associated with SB_POSIXACL allowed filesystems
that don't even support POSIX ACLs at all to raise SB_POSIXACL
purely to avoid umask stripping. That specifically means NFS v4 and
Overlayfs. NFS v4 does it because it delegates this to the server
and Overlayfs because it needs to delegate umask stripping to the
upper filesystem, i.e., the filesystem used as the writable layer.
This went so far that SB_POSIXACL is raised eve on kernels that
don't even have POSIX ACL support at all.
Stop this blatant abuse and add SB_I_NOUMASK which is an internal
superblock flag that filesystems can raise to opt out of umask
handling. That should really only be the two mentioned above. It's
not that we want any filesystems to do this. Ideally we have all
umask handling always in the vfs.
- Make overlayfs use SB_I_NOUMASK too.
- Now that we have SB_I_NOUMASK, stop checking for SB_POSIXACL in
IS_POSIXACL() if the kernel doesn't have support for it. This is a
very old patch but it's only possible to do this now with the wider
cleanup that was done.
- Follow-up work on fake path handling from last cycle. Citing mostly
from Amir:
When overlayfs was first merged, overlayfs files of regular files
and directories, the ones that are installed in file table, had a
"fake" path, namely, f_path is the overlayfs path and f_inode is
the "real" inode on the underlying filesystem.
In v6.5, we took another small step by introducing of the
backing_file container and the file_real_path() helper. This change
allowed vfs and filesystem code to get the "real" path of an
overlayfs backing file. With this change, we were able to make
fsnotify work correctly and report events on the "real" filesystem
objects that were accessed via overlayfs.
This method works fine, but it still leaves the vfs vulnerable to
new code that is not aware of files with fake path. A recent
example is commit db1d1e8b98 ("IMA: use vfs_getattr_nosec to get
the i_version"). This commit uses direct referencing to f_path in
IMA code that otherwise uses file_inode() and file_dentry() to
reference the filesystem objects that it is measuring.
This contains work to switch things around: instead of having
filesystem code opt-in to get the "real" path, have generic code
opt-in for the "fake" path in the few places that it is needed.
Is it far more likely that new filesystems code that does not use
the file_dentry() and file_real_path() helpers will end up causing
crashes or averting LSM/audit rules if we keep the "fake" path
exposed by default.
This change already makes file_dentry() moot, but for now we did
not change this helper just added a WARN_ON() in ovl_d_real() to
catch if we have made any wrong assumptions.
After the dust settles on this change, we can make file_dentry() a
plain accessor and we can drop the inode argument to ->d_real().
- Switch struct file to SLAB_TYPESAFE_BY_RCU. This looks like a small
change but it really isn't and I would like to see everyone on
their tippie toes for any possible bugs from this work.
Essentially we've been doing most of what SLAB_TYPESAFE_BY_RCU for
files since a very long time because of the nasty interactions
between the SCM_RIGHTS file descriptor garbage collection. So
extending it makes a lot of sense but it is a subtle change. There
are almost no places that fiddle with file rcu semantics directly
and the ones that did mess around with struct file internal under
rcu have been made to stop doing that because it really was always
dodgy.
I forgot to put in the link tag for this change and the discussion
in the commit so adding it into the merge message:
https://lore.kernel.org/r/20230926162228.68666-1-mjguzik@gmail.com
Cleanups:
- Various smaller pipe cleanups including the removal of a spin lock
that was only used to protect against writes without pipe_lock()
from O_NOTIFICATION_PIPE aka watch queues. As that was never
implemented remove the additional locking from pipe_write().
- Annotate struct watch_filter with the new __counted_by attribute.
- Clarify do_unlinkat() cleanup so that it doesn't look like an extra
iput() is done that would cause issues.
- Simplify file cleanup when the file has never been opened.
- Use module helper instead of open-coding it.
- Predict error unlikely for stale retry.
- Use WRITE_ONCE() for mount expiry field instead of just commenting
that one hopes the compiler doesn't get smart.
Fixes:
- Fix readahead on block devices.
- Fix writeback when layztime is enabled and inodes whose timestamp
is the only thing that changed reside on wb->b_dirty_time. This
caused excessively large zombie memory cgroup when lazytime was
enabled as such inodes weren't handled fast enough.
- Convert BUG_ON() to WARN_ON_ONCE() in open_last_lookups()"
* tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
file, i915: fix file reference for mmap_singleton()
vfs: Convert BUG_ON to WARN_ON_ONCE in open_last_lookups
writeback, cgroup: switch inodes with dirty timestamps to release dying cgwbs
chardev: Simplify usage of try_module_get()
ovl: rely on SB_I_NOUMASK
fs: fix umask on NFS with CONFIG_FS_POSIX_ACL=n
fs: store real path instead of fake path in backing file f_path
fs: create helper file_user_path() for user displayed mapped file path
fs: get mnt_writers count for an open backing file's real path
vfs: stop counting on gcc not messing with mnt_expiry_mark if not asked
vfs: predict the error in retry_estale as unlikely
backing file: free directly
vfs: fix readahead(2) on block devices
io_uring: use files_lookup_fd_locked()
file: convert to SLAB_TYPESAFE_BY_RCU
vfs: shave work on failed file open
fs: simplify misleading code to remove ambiguity regarding ihold()/iput()
watch_queue: Annotate struct watch_filter with __counted_by
fs/pipe: use spinlock in pipe_read() only if there is a watch_queue
fs/pipe: remove unnecessary spinlock from pipe_write()
...
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Merge tag 'vfs-6.7.super' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull vfs superblock updates from Christian Brauner:
"This contains the work to make block device opening functions return a
struct bdev_handle instead of just a struct block_device. The same
struct bdev_handle is then also passed to block device closing
functions.
This allows us to propagate context from opening to closing a block
device without having to modify all users everytime.
Sidenote, in the future we might even want to try and have block
device opening functions return a struct file directly but that's a
series on top of this.
These are further preparatory changes to be able to count writable
opens and blocking writes to mounted block devices. That's a separate
piece of work for next cycle and for that we absolutely need the
changes to btrfs that have been quietly dropped somehow.
Originally the series contained a patch that removed the old
blkdev_*() helpers. But since this would've caused needles churn in
-next for bcachefs we ended up delaying it.
The second piece of work addresses one of the major annoyances about
the work last cycle, namely that we required dropping s_umount
whenever we used the superblock and fs_holder_ops for a block device.
The reason for that requirement had been that in some codepaths
s_umount could've been taken under disk->open_mutex (that's always
been the case, at least theoretically). For example, on surprise block
device removal or media change. And opening and closing block devices
required grabbing disk->open_mutex as well.
So we did the work and went through the block layer and fixed all
those places so that s_umount is never taken under disk->open_mutex.
This means no more brittle games where we yield and reacquire s_umount
during block device opening and closing and no more requirements where
block devices need to be closed. Filesystems don't need to care about
this.
There's a bunch of other follow-up work such as moving block device
freezing and thawing to holder operations which makes it work for all
block devices and not just the main block device just as we did for
surprise removal. But that is for next cycle.
Tested with fstests for all major fses, blktests, LTP"
* tag 'vfs-6.7.super' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (37 commits)
porting: update locking requirements
fs: assert that open_mutex isn't held over holder ops
block: assert that we're not holding open_mutex over blk_report_disk_dead
block: move bdev_mark_dead out of disk_check_media_change
block: WARN_ON_ONCE() when we remove active partitions
block: simplify bdev_del_partition()
fs: Avoid grabbing sb->s_umount under bdev->bd_holder_lock
jfs: fix log->bdev_handle null ptr deref in lbmStartIO
bcache: Fixup error handling in register_cache()
xfs: Convert to bdev_open_by_path()
reiserfs: Convert to bdev_open_by_dev/path()
ocfs2: Convert to use bdev_open_by_dev()
nfs/blocklayout: Convert to use bdev_open_by_dev/path()
jfs: Convert to bdev_open_by_dev()
f2fs: Convert to bdev_open_by_dev/path()
ext4: Convert to bdev_open_by_dev()
erofs: Convert to use bdev_open_by_path()
btrfs: Convert to bdev_open_by_path()
fs: Convert to bdev_open_by_dev()
mm/swap: Convert to use bdev_open_by_dev()
...
- tracing/kprobes: Fix kernel-doc warnings for the variable length
arguments.
- tracing/kprobes: Fix to count the symbols in modules even if the
module name is not specified so that user can probe the symbols in
the modules without module name.
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Merge tag 'probes-fixes-v6.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes fixes from Masami Hiramatsu:
- tracing/kprobes: Fix kernel-doc warnings for the variable length
arguments
- tracing/kprobes: Fix to count the symbols in modules even if the
module name is not specified so that user can probe the symbols in
the modules without module name
* tag 'probes-fixes-v6.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/kprobes: Fix symbol counting logic by looking at modules as well
tracing/kprobes: Fix the description of variable length arguments
snapshot_test argument is now unused in swsusp_close() and
load_image_and_restore(). Drop it
CC: linux-pm@vger.kernel.org
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: "Rafael J. Wysocki" <rafael@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-17-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>
Convert hibernation code to use bdev_open_by_dev().
CC: linux-pm@vger.kernel.org
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: "Rafael J. Wysocki" <rafael@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-16-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>
Recent changes to count number of matching symbols when creating
a kprobe event failed to take into account kernel modules. As such, it
breaks kprobes on kernel module symbols, by assuming there is no match.
Fix this my calling module_kallsyms_on_each_symbol() in addition to
kallsyms_on_each_match_symbol() to perform a proper counting.
Link: https://lore.kernel.org/all/20231027233126.2073148-1-andrii@kernel.org/
Cc: Francis Laniel <flaniel@linux.microsoft.com>
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Fixes: b022f0c7e4 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fix the following kernel-doc warnings:
kernel/trace/trace_kprobe.c:1029: warning: Excess function parameter 'args' description in '__kprobe_event_gen_cmd_start'
kernel/trace/trace_kprobe.c:1097: warning: Excess function parameter 'args' description in '__kprobe_event_add_fields'
Refer to the usage of variable length arguments elsewhere in the kernel
code, "@..." is the proper way to express it in the description.
Link: https://lore.kernel.org/all/20231027041315.2613166-1-yujie.liu@intel.com/
Fixes: 2a588dd1d5 ("tracing: Add kprobe event command generation functions")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310190437.paI6LYJF-lkp@intel.com/
Signed-off-by: Yujie Liu <yujie.liu@intel.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
On no-MMU, all futexes are treated as private because there is no need
to map a virtual address to physical to match the futex across
processes. This doesn't quite work though, because private futexes
include the current process's mm_struct as part of their key. This makes
it impossible for one process to wake up a shared futex being waited on
in another process.
Fix this bug by excluding the mm_struct from the key. With
a single address space, the futex address is already a unique key.
Fixes: 784bdf3bb6 ("futex: Assume all mappings are private on !MMU systems")
Signed-off-by: Ben Wolsieffer <ben.wolsieffer@hefring.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20231019204548.1236437-2-ben.wolsieffer@hefring.com
irq_remove_generic_chip() calculates the Linux interrupt number for removing the
handler and interrupt chip based on gc::irq_base as a linear function of
the bit positions of set bits in the @msk argument.
When the generic chip is present in an irq domain, i.e. created with a call
to irq_alloc_domain_generic_chips(), gc::irq_base contains not the base
Linux interrupt number. It contains the base hardware interrupt for this
chip. It is set to 0 for the first chip in the domain, 0 + N for the next
chip, where $N is the number of hardware interrupts per chip.
That means the Linux interrupt number cannot be calculated based on
gc::irq_base for irqdomain based chips without a domain map lookup, which
is currently missing.
Rework the code to take the irqdomain case into account and calculate the
Linux interrupt number by a irqdomain lookup of the domain specific
hardware interrupt number.
[ tglx: Massage changelog. Reshuffle the logic and add a proper comment. ]
Fixes: cfefd21e69 ("genirq: Add chip suspend and resume callbacks")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231024150335.322282-1-herve.codina@bootlin.com
commit ef8dd01538 ("genirq/msi: Make interrupt allocation less
convoluted"), reworked the code so that the x86 specific quirk for affinity
setting of non-maskable PCI/MSI interrupts is not longer activated if
necessary.
This could be solved by restoring the original logic in the core MSI code,
but after a deeper analysis it turned out that the quirk flag is not
required at all.
The quirk is only required when the PCI/MSI device cannot mask the MSI
interrupts, which in turn also prevents reservation mode from being enabled
for the affected interrupt.
This allows ot remove the NOMASK quirk bit completely as msi_set_affinity()
can instead check whether reservation mode is enabled for the interrupt,
which gives exactly the same answer.
Even in the momentary non-existing case that the reservation mode would be
not set for a maskable MSI interrupt this would not cause any harm as it
just would cause msi_set_affinity() to go needlessly through the
functionaly equivalent slow path, which works perfectly fine with maskable
interrupts as well.
Rework msi_set_affinity() to query the reservation mode and remove all
NOMASK quirk logic from the core code.
[ tglx: Massaged changelog ]
Fixes: ef8dd01538 ("genirq/msi: Make interrupt allocation less convoluted")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20231026032036.2462428-1-den@valinux.co.jp
When a CPU is about to be offlined, x86 validates that all active
interrupts which are targeted to this CPU can be migrated to the remaining
online CPUs. If not, the offline operation is aborted.
The validation uses irq_matrix_allocated() to retrieve the number of
vectors which are allocated on the outgoing CPU. The returned number of
allocated vectors includes also vectors which are associated to managed
interrupts.
That's overaccounting because managed interrupts are:
- not migrated when the affinity mask of the interrupt targets only
the outgoing CPU
- migrated to another CPU, but in that case the vector is already
pre-allocated on the potential target CPUs and must not be taken into
account.
As a consequence the check whether the remaining online CPUs have enough
capacity for migrating the allocated vectors from the outgoing CPU might
fail incorrectly.
Let irq_matrix_allocated() return only the number of allocated non-managed
interrupts to make this validation check correct.
[ tglx: Amend changelog and fixup kernel-doc comment ]
Fixes: 2f75d9e1c9 ("genirq: Implement bitmap matrix allocator")
Reported-by: Wendy Wang <wendy.wang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20231020072522.557846-1-yu.c.chen@intel.com
When allocating a new pool at runtime, reduce the number of slabs so
that the allocation order is at most MAX_ORDER. This avoids a kernel
warning in __alloc_pages().
The warning is relatively benign, because the pool size is subsequently
reduced when allocation fails, but it is silly to start with a request
that is known to fail, especially since this is the default behavior if
the kernel is built with CONFIG_SWIOTLB_DYNAMIC=y and booted without any
swiotlb= parameter.
Reported-by: Ben Greear <greearb@candelatech.com>
Closes: https://lore.kernel.org/netdev/4f173dd2-324a-0240-ff8d-abf5c191be18@candelatech.com/
Fixes: 1aaa736815 ("swiotlb: allocate a new memory pool when existing pools are full")
Signed-off-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Chen Yu reports a hackbench regression of cluster wakeup when
hackbench threads equal to the CPU number [1]. Analysis shows
it's because we wake up more on the target CPU even if the
prev_cpu is a good wakeup candidate and leads to the decrease
of the CPU utilization.
Generally if the task's prev_cpu is idle we'll wake up the task
on it without scanning. On cluster machines we'll try to wake up
the task in the same cluster of the target for better cache
affinity, so if the prev_cpu is idle but not sharing the same
cluster with the target we'll still try to find an idle CPU within
the cluster. This will improve the performance at low loads on
cluster machines. But in the issue above, if the prev_cpu is idle
but not in the cluster with the target CPU, we'll try to scan an
idle one in the cluster. But since the system is busy, we're
likely to fail the scanning and use target instead, even if
the prev_cpu is idle. Then leads to the regression.
This patch solves this in 2 steps:
o record the prev_cpu/recent_used_cpu if they're good wakeup
candidates but not sharing the cluster with the target.
o on scanning failure use the prev_cpu/recent_used_cpu if
they're recorded as idle
[1] https://lore.kernel.org/all/ZGzDLuVaHR1PAYDt@chenyu5-mobl1/
Closes: https://lore.kernel.org/all/ZGsLy83wPIpamy6x@chenyu5-mobl1/
Reported-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20231019033323.54147-4-yangyicong@huawei.com
For platforms having clusters like Kunpeng920, CPUs within the same cluster
have lower latency when synchronizing and accessing shared resources like
cache. Thus, this patch tries to find an idle cpu within the cluster of the
target CPU before scanning the whole LLC to gain lower latency. This
will be implemented in 2 steps in select_idle_sibling():
1. When the prev_cpu/recent_used_cpu are good wakeup candidates, use them
if they're sharing cluster with the target CPU. Otherwise trying to
scan for an idle CPU in the target's cluster.
2. Scanning the cluster prior to the LLC of the target CPU for an
idle CPU to wakeup.
Testing has been done on Kunpeng920 by pinning tasks to one numa and two
numa. On Kunpeng920, Each numa has 8 clusters and each cluster has 4 CPUs.
With this patch, We noticed enhancement on tbench and netperf within one
numa or cross two numa on top of tip-sched-core commit
9b46f1abc6d4 ("sched/debug: Print 'tgid' in sched_show_task()")
tbench results (node 0):
baseline patched
1: 327.2833 372.4623 ( 13.80%)
4: 1320.5933 1479.8833 ( 12.06%)
8: 2638.4867 2921.5267 ( 10.73%)
16: 5282.7133 5891.5633 ( 11.53%)
32: 9810.6733 9877.3400 ( 0.68%)
64: 7408.9367 7447.9900 ( 0.53%)
128: 6203.2600 6191.6500 ( -0.19%)
tbench results (node 0-1):
baseline patched
1: 332.0433 372.7223 ( 12.25%)
4: 1325.4667 1477.6733 ( 11.48%)
8: 2622.9433 2897.9967 ( 10.49%)
16: 5218.6100 5878.2967 ( 12.64%)
32: 10211.7000 11494.4000 ( 12.56%)
64: 13313.7333 16740.0333 ( 25.74%)
128: 13959.1000 14533.9000 ( 4.12%)
netperf results TCP_RR (node 0):
baseline patched
1: 76546.5033 90649.9867 ( 18.42%)
4: 77292.4450 90932.7175 ( 17.65%)
8: 77367.7254 90882.3467 ( 17.47%)
16: 78519.9048 90938.8344 ( 15.82%)
32: 72169.5035 72851.6730 ( 0.95%)
64: 25911.2457 25882.2315 ( -0.11%)
128: 10752.6572 10768.6038 ( 0.15%)
netperf results TCP_RR (node 0-1):
baseline patched
1: 76857.6667 90892.2767 ( 18.26%)
4: 78236.6475 90767.3017 ( 16.02%)
8: 77929.6096 90684.1633 ( 16.37%)
16: 77438.5873 90502.5787 ( 16.87%)
32: 74205.6635 88301.5612 ( 19.00%)
64: 69827.8535 71787.6706 ( 2.81%)
128: 25281.4366 25771.3023 ( 1.94%)
netperf results UDP_RR (node 0):
baseline patched
1: 96869.8400 110800.8467 ( 14.38%)
4: 97744.9750 109680.5425 ( 12.21%)
8: 98783.9863 110409.9637 ( 11.77%)
16: 99575.0235 110636.2435 ( 11.11%)
32: 95044.7250 97622.8887 ( 2.71%)
64: 32925.2146 32644.4991 ( -0.85%)
128: 12859.2343 12824.0051 ( -0.27%)
netperf results UDP_RR (node 0-1):
baseline patched
1: 97202.4733 110190.1200 ( 13.36%)
4: 95954.0558 106245.7258 ( 10.73%)
8: 96277.1958 105206.5304 ( 9.27%)
16: 97692.7810 107927.2125 ( 10.48%)
32: 79999.6702 103550.2999 ( 29.44%)
64: 80592.7413 87284.0856 ( 8.30%)
128: 27701.5770 29914.5820 ( 7.99%)
Note neither Kunpeng920 nor x86 Jacobsville supports SMT, so the SMT branch
in the code has not been tested but it supposed to work.
Chen Yu also noticed this will improve the performance of tbench and
netperf on a 24 CPUs Jacobsville machine, there are 4 CPUs in one
cluster sharing L2 Cache.
[https://lore.kernel.org/lkml/Ytfjs+m1kUs0ScSn@worktop.programming.kicks-ass.net]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lkml.kernel.org/r/20231019033323.54147-3-yangyicong@huawei.com
Add cpus_share_resources() API. This is the preparation for the
optimization of select_idle_cpu() on platforms with cluster scheduler
level.
On a machine with clusters cpus_share_resources() will test whether
two cpus are within the same cluster. On a non-cluster machine it
will behaves the same as cpus_share_cache(). So we use "resources"
here for cache resources.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-and-reviewed-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20231019033323.54147-2-yangyicong@huawei.com
Igor Raits and Bagas Sanjaya report a RQCF_ACT_SKIP leak warning.
This warning may be triggered in the following situations:
CPU0 CPU1
__schedule()
*rq->clock_update_flags <<= 1;* unregister_fair_sched_group()
pick_next_task_fair+0x4a/0x410 destroy_cfs_bandwidth()
newidle_balance+0x115/0x3e0 for_each_possible_cpu(i) *i=0*
rq_unpin_lock(this_rq, rf) __cfsb_csd_unthrottle()
raw_spin_rq_unlock(this_rq)
rq_lock(*CPU0_rq*, &rf)
rq_clock_start_loop_update()
rq->clock_update_flags & RQCF_ACT_SKIP <--
raw_spin_rq_lock(this_rq)
The purpose of RQCF_ACT_SKIP is to skip the update rq clock,
but the update is very early in __schedule(), but we clear
RQCF_*_SKIP very late, causing it to span that gap above
and triggering this warning.
In __schedule() we can clear the RQCF_*_SKIP flag immediately
after update_rq_clock() to avoid this RQCF_ACT_SKIP leak warning.
And set rq->clock_update_flags to RQCF_UPDATED to avoid
rq->clock_update_flags < RQCF_ACT_SKIP warning that may be triggered later.
Fixes: ebb83d84e4 ("sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()")
Closes: https://lore.kernel.org/all/20230913082424.73252-1-jiahao.os@bytedance.com
Reported-by: Igor Raits <igor.raits@gmail.com>
Reported-by: Bagas Sanjaya <bagasdotme@gmail.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/a5dd536d-041a-2ce9-f4b7-64d8d85c86dc@gmail.com
- kprobe-events: Fix kprobe events to reject if the attached symbol
is not unique name because it may not the function which the user
want to attach to. (User can attach a probe to such symbol using
the nearest unique symbol + offset.)
- selftest: Add a testcase to ensure the kprobe event rejects non
unique symbol correctly.
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Merge tag 'probes-fixes-v6.6-rc6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull probes fixes from Masami Hiramatsu:
- kprobe-events: Fix kprobe events to reject if the attached symbol is
not unique name because it may not the function which the user want
to attach to. (User can attach a probe to such symbol using the
nearest unique symbol + offset.)
- selftest: Add a testcase to ensure the kprobe event rejects non
unique symbol correctly.
* tag 'probes-fixes-v6.6-rc6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
selftests/ftrace: Add new test case which checks non unique symbol
tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
The 'curr' argument of pick_next_entity() has become unused after
the EEVDF changes.
[ mingo: Updated the changelog. ]
Signed-off-by: Yiwei Lin <s921975628@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231020055617.42064-1-s921975628@gmail.com
When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.
Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.
Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@linux.microsoft.com/
Cc: stable@vger.kernel.org
Fixes: 413d37d1eb ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@kernel.org/
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
How ILB is triggered without IPIs is cryptic. Out of mercy for future
code readers, document it in code comments.
The comments are derived from a discussion with Vincent in a past
review.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231020014031.919742-2-joel@joelfernandes.org
The bcachefs implementation of six locks is intended to land in
generic locking code in the long term, but has been pulled into the
bcachefs subsystem for internal use for the time being. This code
lift breaks the bcachefs module build as six locks depend a couple
of the generic locking tracepoints. Export these tracepoint symbols
for bcachefs.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Merge tag 'v6.6-rc7.vfs.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fix from Christian Brauner:
"An openat() call from io_uring triggering an audit call can apparently
cause the refcount of struct filename to be incremented from multiple
threads concurrently during async execution, triggering a refcount
underflow and hitting a BUG_ON(). That bug has been lurking around
since at least v5.16 apparently.
Switch to an atomic counter to fix that. The underflow check is
downgraded from a BUG_ON() to a WARN_ON_ONCE() but we could easily
remove that check altogether tbh"
* tag 'v6.6-rc7.vfs.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
audit,io_uring: io_uring openat triggers audit reference count underflow
Overlayfs uses backing files with "fake" overlayfs f_path and "real"
underlying f_inode, in order to use underlying inode aops for mapped
files and to display the overlayfs path in /proc/<pid>/maps.
In preparation for storing the overlayfs "fake" path instead of the
underlying "real" path in struct backing_file, define a noop helper
file_user_path() that returns f_path for now.
Use the new helper in procfs and kernel logs whenever a path of a
mapped file is displayed to users.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231009153712.1566422-3-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
In recent discussions around some performance improvements in the file
handling area we discussed switching the file cache to rely on
SLAB_TYPESAFE_BY_RCU which allows us to get rid of call_rcu() based
freeing for files completely. This is a pretty sensitive change overall
but it might actually be worth doing.
The main downside is the subtlety. The other one is that we should
really wait for Jann's patch to land that enables KASAN to handle
SLAB_TYPESAFE_BY_RCU UAFs. Currently it doesn't but a patch for this
exists.
With SLAB_TYPESAFE_BY_RCU objects may be freed and reused multiple times
which requires a few changes. So it isn't sufficient anymore to just
acquire a reference to the file in question under rcu using
atomic_long_inc_not_zero() since the file might have already been
recycled and someone else might have bumped the reference.
In other words, callers might see reference count bumps from newer
users. For this reason it is necessary to verify that the pointer is the
same before and after the reference count increment. This pattern can be
seen in get_file_rcu() and __files_get_rcu().
In addition, it isn't possible to access or check fields in struct file
without first aqcuiring a reference on it. Not doing that was always
very dodgy and it was only usable for non-pointer data in struct file.
With SLAB_TYPESAFE_BY_RCU it is necessary that callers first acquire a
reference under rcu or they must hold the files_lock of the fdtable.
Failing to do either one of this is a bug.
Thanks to Jann for pointing out that we need to ensure memory ordering
between reallocations and pointer check by ensuring that all subsequent
loads have a dependency on the second load in get_file_rcu() and
providing a fixup that was folded into this patch.
Cc: Jann Horn <jannh@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Because group consistency is non-atomic between parent (filedesc) and children
(inherited) events, it is possible for PERF_FORMAT_GROUP read() to try and sum
non-matching counter groups -- with non-sensical results.
Add group_generation to distinguish the case where a parent group removes and
adds an event and thus has the same number, but a different configuration of
events as inherited groups.
This became a problem when commit fa8c269353 ("perf/core: Invert
perf_read_group() loops") flipped the order of child_list and sibling_list.
Previously it would iterate the group (sibling_list) first, and for each
sibling traverse the child_list. In this order, only the group composition of
the parent is relevant. By flipping the order the group composition of the
child (inherited) events becomes an issue and the mis-match in group
composition becomes evident.
That said; even prior to this commit, while reading of a group that is not
equally inherited was not broken, it still made no sense.
(Ab)use ECHILD as error return to indicate issues with child process group
composition.
Fixes: fa8c269353 ("perf/core: Invert perf_read_group() loops")
Reported-by: Budimir Markovic <markovicbudimir@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231018115654.GK33217@noisy.programming.kicks-ass.net
