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With the introduction of task_struct::saved_state in commit
5f220be21418 ("sched/wakeup: Prepare for RT sleeping spin/rwlocks")
matching the task state has gotten more complicated. That same commit
changed try_to_wake_up() to consider both states, but
wait_task_inactive() has been neglected.
Sebastian noted that the wait_task_inactive() usage in
ptrace_check_attach() can misbehave when ptrace_stop() is blocked on
the tasklist_lock after it sets TASK_TRACED.
Therefore extract a common helper from ttwu_state_match() and use that
to teach wait_task_inactive() about the PREEMPT_RT locks.
Originally-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lkml.kernel.org/r/20230601091234.GW83892@hirez.programming.kicks-ass.net
While modifying wait_task_inactive() for PREEMPT_RT; the build robot
noted that UP got broken. This led to audit and consideration of the
UP implementation of wait_task_inactive().
It looks like the UP implementation is also broken for PREEMPT;
consider task_current_syscall() getting preempted between the two
calls to wait_task_inactive().
Therefore move the wait_task_inactive() implementation out of
CONFIG_SMP and unconditionally use it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230602103731.GA630648%40hirez.programming.kicks-ass.net
- Remove diagnostics and adjust config for CSD lock diagnostics
- Add a generic IPI-sending tracepoint, as currently there's no easy
way to instrument IPI origins: it's arch dependent and for some
major architectures it's not even consistently available.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull SMP cross-CPU function-call updates from Ingo Molnar:
- Remove diagnostics and adjust config for CSD lock diagnostics
- Add a generic IPI-sending tracepoint, as currently there's no easy
way to instrument IPI origins: it's arch dependent and for some major
architectures it's not even consistently available.
* tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
trace,smp: Trace all smp_function_call*() invocations
trace: Add trace_ipi_send_cpu()
sched, smp: Trace smp callback causing an IPI
smp: reword smp call IPI comment
treewide: Trace IPIs sent via smp_send_reschedule()
irq_work: Trace self-IPIs sent via arch_irq_work_raise()
smp: Trace IPIs sent via arch_send_call_function_ipi_mask()
sched, smp: Trace IPIs sent via send_call_function_single_ipi()
trace: Add trace_ipi_send_cpumask()
kernel/smp: Make csdlock_debug= resettable
locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
locking/csd_lock: Remove added data from CSD lock debugging
locking/csd_lock: Add Kconfig option for csd_debug default
- Allow unprivileged PSI poll()ing
- Fix performance regression introduced by mm_cid
- Improve livepatch stalls by adding livepatch task switching to cond_resched(),
this resolves livepatching busy-loop stalls with certain CPU-bound kthreads.
- Improve sched_move_task() performance on autogroup configs.
- On core-scheduling CPUs, avoid selecting throttled tasks to run
- Misc cleanups, fixes and improvements.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Allow unprivileged PSI poll()ing
- Fix performance regression introduced by mm_cid
- Improve livepatch stalls by adding livepatch task switching to
cond_resched(). This resolves livepatching busy-loop stalls with
certain CPU-bound kthreads
- Improve sched_move_task() performance on autogroup configs
- On core-scheduling CPUs, avoid selecting throttled tasks to run
- Misc cleanups, fixes and improvements
* tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/clock: Fix local_clock() before sched_clock_init()
sched/rt: Fix bad task migration for rt tasks
sched: Fix performance regression introduced by mm_cid
sched/core: Make sched_dynamic_mutex static
sched/psi: Allow unprivileged polling of N*2s period
sched/psi: Extract update_triggers side effect
sched/psi: Rename existing poll members in preparation
sched/psi: Rearrange polling code in preparation
sched/fair: Fix inaccurate tally of ttwu_move_affine
vhost: Fix livepatch timeouts in vhost_worker()
livepatch,sched: Add livepatch task switching to cond_resched()
livepatch: Skip task_call_func() for current task
livepatch: Convert stack entries array to percpu
sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization
sched/core: Reduce cost of sched_move_task when config autogroup
sched/core: Avoid selecting the task that is throttled to run when core-sched enable
sched/topology: Make sched_energy_mutex,update static
- updates to scripts/gdb from Glenn Washburn
- kexec cleanups from Bjorn Helgaas
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Merge tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
"Mainly singleton patches all over the place.
Series of note are:
- updates to scripts/gdb from Glenn Washburn
- kexec cleanups from Bjorn Helgaas"
* tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (50 commits)
mailmap: add entries for Paul Mackerras
libgcc: add forward declarations for generic library routines
mailmap: add entry for Oleksandr
ocfs2: reduce ioctl stack usage
fs/proc: add Kthread flag to /proc/$pid/status
ia64: fix an addr to taddr in huge_pte_offset()
checkpatch: introduce proper bindings license check
epoll: rename global epmutex
scripts/gdb: add GDB convenience functions $lx_dentry_name() and $lx_i_dentry()
scripts/gdb: create linux/vfs.py for VFS related GDB helpers
uapi/linux/const.h: prefer ISO-friendly __typeof__
delayacct: track delays from IRQ/SOFTIRQ
scripts/gdb: timerlist: convert int chunks to str
scripts/gdb: print interrupts
scripts/gdb: raise error with reduced debugging information
scripts/gdb: add a Radix Tree Parser
lib/rbtree: use '+' instead of '|' for setting color.
proc/stat: remove arch_idle_time()
checkpatch: check for misuse of the link tags
checkpatch: allow Closes tags with links
...
Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL
sysbench regression reported by Aaron Lu.
Keep track of the currently allocated mm_cid for each mm/cpu rather than
freeing them immediately on context switch. This eliminates most atomic
operations when context switching back and forth between threads
belonging to different memory spaces in multi-threaded scenarios (many
processes, each with many threads). The per-mm/per-cpu mm_cid values are
serialized by their respective runqueue locks.
Thread migration is handled by introducing invocation to
sched_mm_cid_migrate_to() (with destination runqueue lock held) in
activate_task() for migrating tasks. If the destination cpu's mm_cid is
unset, and if the source runqueue is not actively using its mm_cid, then
the source cpu's mm_cid is moved to the destination cpu on migration.
Introduce a task-work executed periodically, similarly to NUMA work,
which delays reclaim of cid values when they are unused for a period of
time.
Keep track of the allocation time for each per-cpu cid, and let the task
work clear them when they are observed to be older than
SCHED_MM_CID_PERIOD_NS and unused. This task work also clears all
mm_cids which are greater or equal to the Hamming weight of the mm
cidmask to keep concurrency ids compact.
Because we want to ensure the mm_cid converges towards the smaller
values as migrations happen, the prior optimization that was done when
context switching between threads belonging to the same mm is removed,
because it could delay the lazy release of the destination runqueue
mm_cid after it has been replaced by a migration. Removing this prior
optimization is not an issue performance-wise because the introduced
per-mm/per-cpu mm_cid tracking also covers this more specific case.
Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID")
Reported-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Link: https://lore.kernel.org/lkml/20230327080502.GA570847@ziqianlu-desk2/
Delay accounting does not track the delay of IRQ/SOFTIRQ. While
IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such
as when workloads are running on system which is busy handling network
IRQ/SOFTIRQ.
Get the delay of IRQ/SOFTIRQ could help users to reduce such delay. Such
as setting interrupt affinity or task affinity, using kernel thread for
NAPI etc. This is inspired by "sched/psi: Add PSI_IRQ to track
IRQ/SOFTIRQ pressure"[1]. Also fix some code indent problems of older
code.
And update tools/accounting/getdelays.c:
/ # ./getdelays -p 156 -di
print delayacct stats ON
printing IO accounting
PID 156
CPU count real total virtual total delay total delay average
15 15836008 16218149 275700790 18.380ms
IO count delay total delay average
0 0 0.000ms
SWAP count delay total delay average
0 0 0.000ms
RECLAIM count delay total delay average
0 0 0.000ms
THRASHING count delay total delay average
0 0 0.000ms
COMPACT count delay total delay average
0 0 0.000ms
WPCOPY count delay total delay average
36 7586118 0.211ms
IRQ count delay total delay average
42 929161 0.022ms
[1] commit 52b1364ba0b1("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure")
Link: https://lkml.kernel.org/r/202304081728353557233@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: wangyong <wang.yong12@zte.com.cn>
Cc: junhua huang <huang.junhua@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The sched_dynamic_mutex is only used within the file. Make it static.
Fixes: e3ff7c609f39 ("livepatch,sched: Add livepatch task switching to cond_resched()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/oe-kbuild-all/202304062335.tNuUjgsl-lkp@intel.com/
Add explicit _lazy_tlb annotated functions for lazy tlb mm refcounting.
This makes the lazy tlb mm references more obvious, and allows the
refcounting scheme to be modified in later changes. There is no
functional change with this patch.
Link: https://lkml.kernel.org/r/20230203071837.1136453-3-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Context
=======
The newly-introduced ipi_send_cpumask tracepoint has a "callback" parameter
which so far has only been fed with NULL.
While CSD_TYPE_SYNC/ASYNC and CSD_TYPE_IRQ_WORK share a similar backing
struct layout (meaning their callback func can be accessed without caring
about the actual CSD type), CSD_TYPE_TTWU doesn't even have a function
attached to its struct. This means we need to check the type of a CSD
before eventually dereferencing its associated callback.
This isn't as trivial as it sounds: the CSD type is stored in
__call_single_node.u_flags, which get cleared right before the callback is
executed via csd_unlock(). This implies checking the CSD type before it is
enqueued on the call_single_queue, as the target CPU's queue can be flushed
before we get to sending an IPI.
Furthermore, send_call_function_single_ipi() only has a CPU parameter, and
would need to have an additional argument to trickle down the invoked
function. This is somewhat silly, as the extra argument will always be
pushed down to the function even when nothing is being traced, which is
unnecessary overhead.
Changes
=======
send_call_function_single_ipi() is only used by smp.c, and is defined in
sched/core.c as it contains scheduler-specific ops (set_nr_if_polling() of
a CPU's idle task).
Split it into two parts: the scheduler bits remain in sched/core.c, and the
actual IPI emission is moved into smp.c. This lets us define an
__always_inline helper function that can take the related callback as
parameter without creating useless register pressure in the non-traced path
which only gains a (disabled) static branch.
Do the same thing for the multi IPI case.
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230307143558.294354-8-vschneid@redhat.com
send_call_function_single_ipi() is the thing that sends IPIs at the bottom
of smp_call_function*() via either generic_exec_single() or
smp_call_function_many_cond(). Give it an IPI-related tracepoint.
Note that this ends up tracing any IPI sent via __smp_call_single_queue(),
which covers __ttwu_queue_wakelist() and irq_work_queue_on() "for free".
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230307143558.294354-3-vschneid@redhat.com
Some sched_move_task calls are useless because that
task_struct->sched_task_group maybe not changed (equals task_group
of cpu_cgroup) when system enable autogroup. So do some checks in
sched_move_task.
sched_move_task eg:
task A belongs to cpu_cgroup0 and autogroup0, it will always belong
to cpu_cgroup0 when do_exit. So there is no need to do {de|en}queue.
The call graph is as follow.
do_exit
sched_autogroup_exit_task
sched_move_task
dequeue_task
sched_change_group
A.sched_task_group = sched_get_task_group (=cpu_cgroup0)
enqueue_task
Performance results:
===========================
1. env
cpu: bogomips=4600.00
kernel: 6.3.0-rc3
cpu_cgroup: 6:cpu,cpuacct:/user.slice
2. cmds
do_exit script:
for i in {0..10000}; do
sleep 0 &
done
wait
Run the above script, then use the following bpftrace cmd to get
the cost of sched_move_task:
bpftrace -e 'k:sched_move_task { @ts[tid] = nsecs; }
kr:sched_move_task /@ts[tid]/
{ @ns += nsecs - @ts[tid]; delete(@ts[tid]); }'
3. cost time(ns):
without patch: 43528033
with patch: 18541416
diff:-24986617 -57.4%
As the result show, the patch will save 57.4% in the scenario.
Signed-off-by: wuchi <wuchi.zero@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230321064459.39421-1-wuchi.zero@gmail.com
When {rt, cfs}_rq or dl task is throttled, since cookied tasks
are not dequeued from the core tree, So sched_core_find() and
sched_core_next() may return throttled task, which may
cause throttled task to run on the CPU.
So we add checks in sched_core_find() and sched_core_next()
to make sure that the return is a runnable task that is
not throttled.
Co-developed-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230316081806.69544-1-jiahao.os@bytedance.com
Commit 829c1651e9c4 ("sched/fair: sanitize vruntime of entity being placed")
fixes an overflowing bug, but ignore a case that se->exec_start is reset
after a migration.
For fixing this case, we delay the reset of se->exec_start after
placing the entity which se->exec_start to detect long sleeping task.
In order to take into account a possible divergence between the clock_task
of 2 rqs, we increase the threshold to around 104 days.
Fixes: 829c1651e9c4 ("sched/fair: sanitize vruntime of entity being placed")
Originally-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Qiao <zhangqiao22@huawei.com>
Link: https://lore.kernel.org/r/20230317160810.107988-1-vincent.guittot@linaro.org
The getaffinity() system call uses 'cpumask_size()' to decide how big
the CPU mask is - so far so good. It is indeed the allocation size of a
cpumask.
But the code also assumes that the whole allocation is initialized
without actually doing so itself. That's wrong, because we might have
fixed-size allocations (making copying and clearing more efficient), but
not all of it is then necessarily used if 'nr_cpu_ids' is smaller.
Having checked other users of 'cpumask_size()', they all seem to be ok,
either using it purely for the allocation size, or explicitly zeroing
the cpumask before using the size in bytes to copy it.
See for example the ublk_ctrl_get_queue_affinity() function that uses
the proper 'zalloc_cpumask_var()' to make sure that the whole mask is
cleared, whether the storage is on the stack or if it was an external
allocation.
Fix this by just zeroing the allocation before using it. Do the same
for the compat version of sched_getaffinity(), which had the same logic.
Also, for consistency, make sched_getaffinity() use 'cpumask_bits()' to
access the bits. For a cpumask_var_t, it ends up being a pointer to the
same data either way, but it's just a good idea to treat it like you
would a 'cpumask_t'. The compat case already did that.
Reported-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/lkml/7d026744-6bd6-6827-0471-b5e8eae0be3f@arm.com/
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This pull request contains the following branches:
doc.2023.01.05a: Documentation updates.
fixes.2023.01.23a: Miscellaneous fixes, perhaps most notably:
o Throttling callback invocation based on the number of callbacks
that are now ready to invoke instead of on the total number
of callbacks.
o Several patches that suppress false-positive boot-time
diagnostics, for example, due to lockdep not yet being
initialized.
o Make expedited RCU CPU stall warnings dump stacks of any tasks
that are blocking the stalled grace period. (Normal RCU CPU
stall warnings have doen this for mnay years.)
o Lazy-callback fixes to avoid delays during boot, suspend, and
resume. (Note that lazy callbacks must be explicitly enabled,
so this should not (yet) affect production use cases.)
kvfree.2023.01.03a: Cause kfree_rcu() and friends to take advantage of
polled grace periods, thus reducing memory footprint by almost
two orders of magnitude, admittedly on a microbenchmark.
This series also begins the transition from kfree_rcu(p) to
kfree_rcu_mightsleep(p). This transition was motivated by bugs
where kfree_rcu(p), which can block, was typed instead of the
intended kfree_rcu(p, rh).
srcu.2023.01.03a: SRCU updates, perhaps most notably fixing a bug that
causes SRCU to fail when booted on a system with a non-zero boot
CPU. This surprising situation actually happens for kdump kernels
on the powerpc architecture. It also adds an srcu_down_read()
and srcu_up_read(), which act like srcu_read_lock() and
srcu_read_unlock(), but allow an SRCU read-side critical section
to be handed off from one task to another.
srcu-always.2023.02.02a: Cleans up the now-useless SRCU Kconfig option.
There are a few more commits that are not yet acked or pulled
into maintainer trees, and these will be in a pull request for
a later merge window.
tasks.2023.01.03a: RCU-tasks updates, perhaps most notably these fixes:
o A strange interaction between PID-namespace unshare and the
RCU-tasks grace period that results in a low-probability but
very real hang.
o A race between an RCU tasks rude grace period on a single-CPU
system and CPU-hotplug addition of the second CPU that can result
in a too-short grace period.
o A race between shrinking RCU tasks down to a single callback list
and queuing a new callback to some other CPU, but where that
queuing is delayed for more than an RCU grace period. This can
result in that callback being stranded on the non-boot CPU.
torture.2023.01.05a: Torture-test updates and fixes.
torturescript.2023.01.03a: Torture-test scripting updates and fixes.
stall.2023.01.09a: Provide additional RCU CPU stall-warning information
in kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y, and
restore the full five-minute timeout limit for expedited RCU
CPU stall warnings.
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Merge tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU updates from Paul McKenney:
- Documentation updates
- Miscellaneous fixes, perhaps most notably:
- Throttling callback invocation based on the number of callbacks
that are now ready to invoke instead of on the total number of
callbacks
- Several patches that suppress false-positive boot-time
diagnostics, for example, due to lockdep not yet being
initialized
- Make expedited RCU CPU stall warnings dump stacks of any tasks
that are blocking the stalled grace period. (Normal RCU CPU
stall warnings have done this for many years)
- Lazy-callback fixes to avoid delays during boot, suspend, and
resume. (Note that lazy callbacks must be explicitly enabled, so
this should not (yet) affect production use cases)
- Make kfree_rcu() and friends take advantage of polled grace periods,
thus reducing memory footprint by almost two orders of magnitude,
admittedly on a microbenchmark
This also begins the transition from kfree_rcu(p) to
kfree_rcu_mightsleep(p). This transition was motivated by bugs where
kfree_rcu(p), which can block, was typed instead of the intended
kfree_rcu(p, rh)
- SRCU updates, perhaps most notably fixing a bug that causes SRCU to
fail when booted on a system with a non-zero boot CPU. This
surprising situation actually happens for kdump kernels on the
powerpc architecture
This also adds an srcu_down_read() and srcu_up_read(), which act like
srcu_read_lock() and srcu_read_unlock(), but allow an SRCU read-side
critical section to be handed off from one task to another
- Clean up the now-useless SRCU Kconfig option
There are a few more commits that are not yet acked or pulled into
maintainer trees, and these will be in a pull request for a later
merge window
- RCU-tasks updates, perhaps most notably these fixes:
- A strange interaction between PID-namespace unshare and the
RCU-tasks grace period that results in a low-probability but
very real hang
- A race between an RCU tasks rude grace period on a single-CPU
system and CPU-hotplug addition of the second CPU that can
result in a too-short grace period
- A race between shrinking RCU tasks down to a single callback
list and queuing a new callback to some other CPU, but where
that queuing is delayed for more than an RCU grace period. This
can result in that callback being stranded on the non-boot CPU
- Torture-test updates and fixes
- Torture-test scripting updates and fixes
- Provide additional RCU CPU stall-warning information in kernels built
with CONFIG_RCU_CPU_STALL_CPUTIME=y, and restore the full five-minute
timeout limit for expedited RCU CPU stall warnings
* tag 'rcu.2023.02.10a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (80 commits)
rcu/kvfree: Add kvfree_rcu_mightsleep() and kfree_rcu_mightsleep()
kernel/notifier: Remove CONFIG_SRCU
init: Remove "select SRCU"
fs/quota: Remove "select SRCU"
fs/notify: Remove "select SRCU"
fs/btrfs: Remove "select SRCU"
fs: Remove CONFIG_SRCU
drivers/pci/controller: Remove "select SRCU"
drivers/net: Remove "select SRCU"
drivers/md: Remove "select SRCU"
drivers/hwtracing/stm: Remove "select SRCU"
drivers/dax: Remove "select SRCU"
drivers/base: Remove CONFIG_SRCU
rcu: Disable laziness if lazy-tracking says so
rcu: Track laziness during boot and suspend
rcu: Remove redundant call to rcu_boost_kthread_setaffinity()
rcu: Allow up to five minutes expedited RCU CPU stall-warning timeouts
rcu: Align the output of RCU CPU stall warning messages
rcu: Add RCU stall diagnosis information
sched: Add helper nr_context_switches_cpu()
...
- Improve the scalability of the CFS bandwidth unthrottling logic
with large number of CPUs.
- Fix & rework various cpuidle routines, simplify interaction with
the generic scheduler code. Add __cpuidle methods as noinstr to
objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks.
- Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS,
to query previously issued registrations.
- Limit scheduler slice duration to the sysctl_sched_latency period,
to improve scheduling granularity with a large number of SCHED_IDLE
tasks.
- Debuggability enhancement on sys_exit(): warn about disabled IRQs,
but also enable them to prevent a cascade of followup problems and
repeat warnings.
- Fix the rescheduling logic in prio_changed_dl().
- Micro-optimize cpufreq and sched-util methods.
- Micro-optimize ttwu_runnable()
- Micro-optimize the idle-scanning in update_numa_stats(),
select_idle_capacity() and steal_cookie_task().
- Update the RSEQ code & self-tests
- Constify various scheduler methods
- Remove unused methods
- Refine __init tags
- Documentation updates
- ... Misc other cleanups, fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve the scalability of the CFS bandwidth unthrottling logic with
large number of CPUs.
- Fix & rework various cpuidle routines, simplify interaction with the
generic scheduler code. Add __cpuidle methods as noinstr to objtool's
noinstr detection and fix boatloads of cpuidle bugs & quirks.
- Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query
previously issued registrations.
- Limit scheduler slice duration to the sysctl_sched_latency period, to
improve scheduling granularity with a large number of SCHED_IDLE
tasks.
- Debuggability enhancement on sys_exit(): warn about disabled IRQs,
but also enable them to prevent a cascade of followup problems and
repeat warnings.
- Fix the rescheduling logic in prio_changed_dl().
- Micro-optimize cpufreq and sched-util methods.
- Micro-optimize ttwu_runnable()
- Micro-optimize the idle-scanning in update_numa_stats(),
select_idle_capacity() and steal_cookie_task().
- Update the RSEQ code & self-tests
- Constify various scheduler methods
- Remove unused methods
- Refine __init tags
- Documentation updates
- Misc other cleanups, fixes
* tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits)
sched/rt: pick_next_rt_entity(): check list_entry
sched/deadline: Add more reschedule cases to prio_changed_dl()
sched/fair: sanitize vruntime of entity being placed
sched/fair: Remove capacity inversion detection
sched/fair: unlink misfit task from cpu overutilized
objtool: mem*() are not uaccess safe
cpuidle: Fix poll_idle() noinstr annotation
sched/clock: Make local_clock() noinstr
sched/clock/x86: Mark sched_clock() noinstr
x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read()
x86/atomics: Always inline arch_atomic64*()
cpuidle: tracing, preempt: Squash _rcuidle tracing
cpuidle: tracing: Warn about !rcu_is_watching()
cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG
cpuidle: drivers: firmware: psci: Dont instrument suspend code
KVM: selftests: Fix build of rseq test
exit: Detect and fix irq disabled state in oops
cpuidle, arm64: Fix the ARM64 cpuidle logic
cpuidle: mvebu: Fix duplicate flags assignment
sched/fair: Limit sched slice duration
...
Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask"), a successful call to sched_setaffinity() should always save
the user requested cpu affinity mask in a task's user_cpus_ptr. However,
when the given cpu mask is the same as the current one, user_cpus_ptr
is not updated. Fix this by saving the user mask in this case too.
Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230203181849.221943-1-longman@redhat.com
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Merge tag 'v6.2-rc6' into sched/core, to pick up fixes
Pick up fixes before merging another batch of cpuidle updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The kernel commit 9a5418bc48ba ("sched/core: Use kfree_rcu() in
do_set_cpus_allowed()") introduces a bug for kernels built with non-SMP
configs. Calling sched_setaffinity() on such a uniprocessor kernel will
cause cpumask_copy() to be called with a NULL pointer leading to general
protection fault. This is not really a problem in real use cases as
there aren't that many uniprocessor kernel configs in use and calling
sched_setaffinity() on such a uniprocessor system doesn't make sense.
Fix this problem by making sure cpumask_copy() will not be called in
such a case.
Fixes: 9a5418bc48ba ("sched/core: Use kfree_rcu() in do_set_cpus_allowed()")
Reported-by: kernel test robot <yujie.liu@intel.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230115193122.563036-1-longman@redhat.com
Commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") may call kfree() if user_cpus_ptr was previously
set. Unfortunately, some of the callers of do_set_cpus_allowed()
may have pi_lock held when calling it. So the following splats may be
printed especially when running with a PREEMPT_RT kernel:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context
To avoid these problems, kfree_rcu() is used instead. An internal
cpumask_rcuhead union is created for the sole purpose of facilitating
the use of kfree_rcu() to free the cpumask.
Since user_cpus_ptr is not being used in non-SMP configs, the newly
introduced alloc_user_cpus_ptr() helper will return NULL in this case
and sched_setaffinity() is modified to handle this special case.
Fixes: 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221231041120.440785-3-longman@redhat.com
Since commit 07ec77a1d4e8 ("sched: Allow task CPU affinity to be
restricted on asymmetric systems"), the setting and clearing of
user_cpus_ptr are done under pi_lock for arm64 architecture. However,
dup_user_cpus_ptr() accesses user_cpus_ptr without any lock
protection. Since sched_setaffinity() can be invoked from another
process, the process being modified may be undergoing fork() at
the same time. When racing with the clearing of user_cpus_ptr in
__set_cpus_allowed_ptr_locked(), it can lead to user-after-free and
possibly double-free in arm64 kernel.
Commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask") fixes this problem as user_cpus_ptr, once set, will never
be cleared in a task's lifetime. However, this bug was re-introduced
in commit 851a723e45d1 ("sched: Always clear user_cpus_ptr in
do_set_cpus_allowed()") which allows the clearing of user_cpus_ptr in
do_set_cpus_allowed(). This time, it will affect all arches.
Fix this bug by always clearing the user_cpus_ptr of the newly
cloned/forked task before the copying process starts and check the
user_cpus_ptr state of the source task under pi_lock.
Note to stable, this patch won't be applicable to stable releases.
Just copy the new dup_user_cpus_ptr() function over.
Fixes: 07ec77a1d4e8 ("sched: Allow task CPU affinity to be restricted on asymmetric systems")
Fixes: 851a723e45d1 ("sched: Always clear user_cpus_ptr in do_set_cpus_allowed()")
Reported-by: David Wang 王标 <wangbiao3@xiaomi.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221231041120.440785-2-longman@redhat.com
In order for the scheduler to be frequency invariant we measure the
ratio between the maximum CPU frequency and the actual CPU frequency.
During long tickless periods of time the calculations that keep track
of that might overflow, in the function scale_freq_tick():
if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
goto error;
eventually forcing the kernel to disable the feature for all CPUs,
and show the warning message:
"Scheduler frequency invariance went wobbly, disabling!".
Let's avoid that by limiting the frequency invariant calculations
to CPUs with regular tick.
Fixes: e2b0d619b400 ("x86, sched: check for counters overflow in frequency invariant accounting")
Suggested-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Yair Podemsky <ypodemsk@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Link: https://lore.kernel.org/r/20221130125121.34407-1-ypodemsk@redhat.com
ttwu_do_activate() is used for a complete wakeup, in which we will
activate_task() and use ttwu_do_wakeup() to mark the task runnable
and perform wakeup-preemption, also call class->task_woken() callback
and update the rq->idle_stamp.
Since ttwu_runnable() is not a complete wakeup, don't need all those
done in ttwu_do_wakeup(), so we can move those to ttwu_do_activate()
to simplify ttwu_do_wakeup(), making it only mark the task runnable
to be reused in ttwu_runnable() and try_to_wake_up().
This patch should not have any functional changes.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20221223103257.4962-2-zhouchengming@bytedance.com
ttwu_runnable() is used as a fast wakeup path when the wakee task
is running on CPU or runnable on RQ, in both cases we can just
set its state to TASK_RUNNING to prevent a sleep.
If the wakee task is on_cpu running, we don't need to update_rq_clock()
or check_preempt_curr().
But if the wakee task is on_rq && !on_cpu (e.g. an IRQ hit before
the task got to schedule() and the task been preempted), we should
check_preempt_curr() to see if it can preempt the current running.
This also removes the class->task_woken() callback from ttwu_runnable(),
which wasn't required per the RT/DL implementations: any required push
operation would have been queued during class->set_next_task() when p
got preempted.
ttwu_runnable() also loses the update to rq->idle_stamp, as by definition
the rq cannot be idle in this scenario.
Suggested-by: Valentin Schneider <vschneid@redhat.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20221223103257.4962-1-zhouchengming@bytedance.com
Add a function nr_context_switches_cpu() that returns number of context
switches since boot on the specified CPU. This information will be used
to diagnose RCU CPU stalls.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
sched_mm_cid_after_execve() does not expect NULL t->mm, but it may happen
if a usermodehelper kthread fails when attempting to execute a binary.
sched_mm_cid_fork() can be issued from a usermodehelper kthread, which
has t->flags PF_KTHREAD set.
Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID")
Reported-by: kernel test robot <yujie.liu@intel.com>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/oe-lkp/202212301353.5c959d72-yujie.liu@intel.com
When select_idle_capacity() starts scanning for an idle CPU, it starts
with target CPU that has already been checked in select_idle_sibling().
So we start checking from the next CPU and try the target CPU at the end.
Similarly for task_numa_assign(), we have just checked numa_migrate_on
of dst_cpu, so start from the next CPU. This also works for
steal_cookie_task(), the first scan must fail and start directly
from the next one.
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20221216062406.7812-3-jiahao.os@bytedance.com
With a modified container_of() that preserves constness, the compiler
finds some pointers which should have been marked as const. task_of()
also needs to become const-preserving for the !FAIR_GROUP_SCHED case so
that cfs_rq_of() can take a const argument. No change to generated code.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221212144946.2657785-1-willy@infradead.org
This feature allows the scheduler to expose a per-memory map concurrency
ID to user-space. This concurrency ID is within the possible cpus range,
and is temporarily (and uniquely) assigned while threads are actively
running within a memory map. If a memory map has fewer threads than
cores, or is limited to run on few cores concurrently through sched
affinity or cgroup cpusets, the concurrency IDs will be values close
to 0, thus allowing efficient use of user-space memory for per-cpu
data structures.
This feature is meant to be exposed by a new rseq thread area field.
The primary purpose of this feature is to do the heavy-lifting needed
by memory allocators to allow them to use per-cpu data structures
efficiently in the following situations:
- Single-threaded applications,
- Multi-threaded applications on large systems (many cores) with limited
cpu affinity mask,
- Multi-threaded applications on large systems (many cores) with
restricted cgroup cpuset per container.
One of the key concern from scheduler maintainers is the overhead
associated with additional spin locks or atomic operations in the
scheduler fast-path. This is why the following optimization is
implemented.
On context switch between threads belonging to the same memory map,
transfer the mm_cid from prev to next without any atomic ops. This
takes care of use-cases involving frequent context switch between
threads belonging to the same memory map.
Additional optimizations can be done if the spin locks added when
context switching between threads belonging to different memory maps end
up being a performance bottleneck. Those are left out of this patch
though. A performance impact would have to be clearly demonstrated to
justify the added complexity.
The credit goes to Paul Turner (Google) for the original virtual cpu id
idea. This feature is implemented based on the discussions with Paul
Turner and Peter Oskolkov (Google), but I took the liberty to implement
scheduler fast-path optimizations and my own NUMA-awareness scheme. The
rumor has it that Google have been running a rseq vcpu_id extension
internally in production for a year. The tcmalloc source code indeed has
comments hinting at a vcpu_id prototype extension to the rseq system
call [1].
The following benchmarks do not show any significant overhead added to
the scheduler context switch by this feature:
* perf bench sched messaging (process)
Baseline: 86.5±0.3 ms
With mm_cid: 86.7±2.6 ms
* perf bench sched messaging (threaded)
Baseline: 84.3±3.0 ms
With mm_cid: 84.7±2.6 ms
* hackbench (process)
Baseline: 82.9±2.7 ms
With mm_cid: 82.9±2.9 ms
* hackbench (threaded)
Baseline: 85.2±2.6 ms
With mm_cid: 84.4±2.9 ms
[1] https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L26
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221122203932.231377-8-mathieu.desnoyers@efficios.com
- Convert flexible array members, fix -Wstringop-overflow warnings,
and fix KCFI function type mismatches that went ignored by
maintainers (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook).
- Remove the remaining side-effect users of ksize() by converting
dma-buf, btrfs, and coredump to using kmalloc_size_roundup(),
add more __alloc_size attributes, and introduce full testing
of all allocator functions. Finally remove the ksize() side-effect
so that each allocation-aware checker can finally behave without
exceptions.
- Introduce oops_limit (default 10,000) and warn_limit (default off)
to provide greater granularity of control for panic_on_oops and
panic_on_warn (Jann Horn, Kees Cook).
- Introduce overflows_type() and castable_to_type() helpers for
cleaner overflow checking.
- Improve code generation for strscpy() and update str*() kern-doc.
- Convert strscpy and sigphash tests to KUnit, and expand memcpy
tests.
- Always use a non-NULL argument for prepare_kernel_cred().
- Disable structleak plugin in FORTIFY KUnit test (Anders Roxell).
- Adjust orphan linker section checking to respect CONFIG_WERROR
(Xin Li).
- Make sure siginfo is cleared for forced SIGKILL (haifeng.xu).
- Fix um vs FORTIFY warnings for always-NULL arguments.
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Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull kernel hardening updates from Kees Cook:
- Convert flexible array members, fix -Wstringop-overflow warnings, and
fix KCFI function type mismatches that went ignored by maintainers
(Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)
- Remove the remaining side-effect users of ksize() by converting
dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
more __alloc_size attributes, and introduce full testing of all
allocator functions. Finally remove the ksize() side-effect so that
each allocation-aware checker can finally behave without exceptions
- Introduce oops_limit (default 10,000) and warn_limit (default off) to
provide greater granularity of control for panic_on_oops and
panic_on_warn (Jann Horn, Kees Cook)
- Introduce overflows_type() and castable_to_type() helpers for cleaner
overflow checking
- Improve code generation for strscpy() and update str*() kern-doc
- Convert strscpy and sigphash tests to KUnit, and expand memcpy tests
- Always use a non-NULL argument for prepare_kernel_cred()
- Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)
- Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
Li)
- Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)
- Fix um vs FORTIFY warnings for always-NULL arguments
* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
ksmbd: replace one-element arrays with flexible-array members
hpet: Replace one-element array with flexible-array member
um: virt-pci: Avoid GCC non-NULL warning
signal: Initialize the info in ksignal
lib: fortify_kunit: build without structleak plugin
panic: Expose "warn_count" to sysfs
panic: Introduce warn_limit
panic: Consolidate open-coded panic_on_warn checks
exit: Allow oops_limit to be disabled
exit: Expose "oops_count" to sysfs
exit: Put an upper limit on how often we can oops
panic: Separate sysctl logic from CONFIG_SMP
mm/pgtable: Fix multiple -Wstringop-overflow warnings
mm: Make ksize() a reporting-only function
kunit/fortify: Validate __alloc_size attribute results
drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
driver core: Add __alloc_size hint to devm allocators
overflow: Introduce overflows_type() and castable_to_type()
coredump: Proactively round up to kmalloc bucket size
...
Only step forward on the sysctl cleanups for this cycle. This
has been on linux-next since September and this time it goes
with a "Yeah, think so, it just moves stuff around a bit" from
Peter Zijlstra.
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Merge tag 'sysctl-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull sysctl updates from Luis Chamberlain:
"Only a small step forward on the sysctl cleanups for this cycle"
* tag 'sysctl-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
sched: Move numa_balancing sysctls to its own file
- Implement persistent user-requested affinity: introduce affinity_context::user_mask
and unconditionally preserve the user-requested CPU affinity masks, for long-lived
tasks to better interact with cpusets & CPU hotplug events over longer timespans,
without destroying the original affinity intent if the underlying topology changes.
- Uclamp updates: fix relationship between uclamp and fits_capacity()
- PSI fixes
- Misc fixes & updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Implement persistent user-requested affinity: introduce
affinity_context::user_mask and unconditionally preserve the
user-requested CPU affinity masks, for long-lived tasks to better
interact with cpusets & CPU hotplug events over longer timespans,
without destroying the original affinity intent if the underlying
topology changes.
- Uclamp updates: fix relationship between uclamp and fits_capacity()
- PSI fixes
- Misc fixes & updates
* tag 'sched-core-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Clear ttwu_pending after enqueue_task()
sched/psi: Use task->psi_flags to clear in CPU migration
sched/psi: Stop relying on timer_pending() for poll_work rescheduling
sched/psi: Fix avgs_work re-arm in psi_avgs_work()
sched/psi: Fix possible missing or delayed pending event
sched: Always clear user_cpus_ptr in do_set_cpus_allowed()
sched: Enforce user requested affinity
sched: Always preserve the user requested cpumask
sched: Introduce affinity_context
sched: Add __releases annotations to affine_move_task()
sched/fair: Check if prev_cpu has highest spare cap in feec()
sched/fair: Consider capacity inversion in util_fits_cpu()
sched/fair: Detect capacity inversion
sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition
sched/uclamp: Make cpu_overutilized() use util_fits_cpu()
sched/uclamp: Make asym_fits_capacity() use util_fits_cpu()
sched/uclamp: Make select_idle_capacity() use util_fits_cpu()
sched/uclamp: Fix fits_capacity() check in feec()
sched/uclamp: Make task_fits_capacity() use util_fits_cpu()
sched/uclamp: Fix relationship between uclamp and migration margin
Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
their own warnings, and each check "panic_on_warn". Consolidate this
into a single function so that future instrumentation can be added in
a single location.
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Gow <davidgow@google.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org
The sysctl_numa_balancing_promote_rate_limit and sysctl_numa_balancing
are part of sched, move them to its own file.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
We found a long tail latency in schbench whem m*t is close to nr_cpus.
(e.g., "schbench -m 2 -t 16" on a machine with 32 cpus.)
This is because when the wakee cpu is idle, rq->ttwu_pending is cleared
too early, and idle_cpu() will return true until the wakee task enqueued.
This will mislead the waker when selecting idle cpu, and wake multiple
worker threads on the same wakee cpu. This situation is enlarged by
commit f3dd3f674555 ("sched: Remove the limitation of WF_ON_CPU on
wakelist if wakee cpu is idle") because it tends to use wakelist.
Here is the result of "schbench -m 2 -t 16" on a VM with 32vcpu
(Intel(R) Xeon(R) Platinum 8369B).
Latency percentiles (usec):
base base+revert_f3dd3f674555 base+this_patch
50.0000th: 9 13 9
75.0000th: 12 19 12
90.0000th: 15 22 15
95.0000th: 18 24 17
*99.0000th: 27 31 24
99.5000th: 3364 33 27
99.9000th: 12560 36 30
We also tested on unixbench and hackbench, and saw no performance
change.
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20221104023601.12844-1-dtcccc@linux.alibaba.com
There is a very narrow race between schedule() and task_call_func().
CPU0 CPU1
__schedule()
rq_lock();
prev_state = READ_ONCE(prev->__state);
if (... && prev_state) {
deactivate_tasl(rq, prev, ...)
prev->on_rq = 0;
task_call_func()
raw_spin_lock_irqsave(p->pi_lock);
state = READ_ONCE(p->__state);
smp_rmb();
if (... || p->on_rq) // false!!!
rq = __task_rq_lock()
ret = func();
next = pick_next_task();
rq = context_switch(prev, next)
prepare_lock_switch()
spin_release(&__rq_lockp(rq)->dep_map...)
So while the task is on it's way out, it still holds rq->lock for a
little while, and right then task_call_func() comes in and figures it
doesn't need rq->lock anymore (because the task is already dequeued --
but still running there) and then the __set_task_frozen() thing observes
it's holding rq->lock and yells murder.
Avoid this by waiting for p->on_cpu to get cleared, which guarantees
the task is fully finished on the old CPU.
( While arguably the fixes tag is 'wrong' -- none of the previous
task_call_func() users appears to care for this case. )
Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lkml.kernel.org/r/Y1kdRNNfUeAU+FNl@hirez.programming.kicks-ass.net
The commit d583d360a620 ("psi: Fix psi state corruption when schedule()
races with cgroup move") fixed a race problem by making cgroup_move_task()
use task->psi_flags instead of looking at the scheduler state.
We can extend task->psi_flags usage to CPU migration, which should be
a minor optimization for performance and code simplicity.
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20220926081931.45420-1-zhouchengming@bytedance.com
The do_set_cpus_allowed() function is used by either kthread_bind() or
select_fallback_rq(). In both cases the user affinity (if any) should be
destroyed too.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220922180041.1768141-6-longman@redhat.com
It was found that the user requested affinity via sched_setaffinity()
can be easily overwritten by other kernel subsystems without an easy way
to reset it back to what the user requested. For example, any change
to the current cpuset hierarchy may reset the cpumask of the tasks in
the affected cpusets to the default cpuset value even if those tasks
have pre-existing user requested affinity. That is especially easy to
trigger under a cgroup v2 environment where writing "+cpuset" to the
root cgroup's cgroup.subtree_control file will reset the cpus affinity
of all the processes in the system.
That is problematic in a nohz_full environment where the tasks running
in the nohz_full CPUs usually have their cpus affinity explicitly set
and will behave incorrectly if cpus affinity changes.
Fix this problem by looking at user_cpus_ptr in __set_cpus_allowed_ptr()
and use it to restrcit the given cpumask unless there is no overlap. In
that case, it will fallback to the given one. The SCA_USER flag is
reused to indicate intent to set user_cpus_ptr and so user_cpus_ptr
masking should be skipped. In addition, masking should also be skipped
if any of the SCA_MIGRATE_* flag is set.
All callers of set_cpus_allowed_ptr() will be affected by this change.
A scratch cpumask is added to percpu runqueues structure for doing
additional masking when user_cpus_ptr is set.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220922180041.1768141-4-longman@redhat.com
Unconditionally preserve the user requested cpumask on
sched_setaffinity() calls. This allows using it outside of the fairly
narrow restrict_cpus_allowed_ptr() use-case and fix some cpuset issues
that currently suffer destruction of cpumasks.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220922180041.1768141-3-longman@redhat.com
In order to prepare for passing through additional data through the
affinity call-chains, convert the mask and flags argument into a
structure.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220922180041.1768141-5-longman@redhat.com
affine_move_task() assumes task_rq_lock() has been called and it does
an implicit task_rq_unlock() before returning. Add the appropriate
__releases annotations to make this clear.
A typo error in comment is also fixed.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220922180041.1768141-2-longman@redhat.com
As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024,
it'll always pick the previous CPU because fits_capacity() will always
return false in this case.
The new util_fits_cpu() logic should handle this correctly for us beside
more corner cases where similar failures could occur, like when using
UCLAMP_MAX.
We open code uclamp_rq_util_with() except for the clamp() part,
util_fits_cpu() needs the 'raw' values to be passed to it.
Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp
value for the rq. Makes the code more readable and ensures the right
rules (use READ_ONCE/WRITE_ONCE) are respected transparently.
[1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html
Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions")
Reported-by: Yun Hsiang <hsiang023167@gmail.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com
Introduce distinct struct balance_callback instead of performing function
pointer casting which will trip CFI. Avoids warnings as found by Clang's
future -Wcast-function-type-strict option:
In file included from kernel/sched/core.c:84:
kernel/sched/sched.h:1755:15: warning: cast from 'void (*)(struct rq *)' to 'void (*)(struct callback_head *)' converts to incompatible function type [-Wcast-function-type-strict]
head->func = (void (*)(struct callback_head *))func;
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
No binary differences result from this change.
This patch is a cleanup based on Brad Spengler/PaX Team's modifications
to sched code in their last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code
are mine and don't reflect the original grsecurity/PaX code.
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/1724
Link: https://lkml.kernel.org/r/20221008000758.2957718-1-keescook@chromium.org
- Various performance optimizations, resulting in a 4%-9% speedup
in the mmtests/config-scheduler-perfpipe micro-benchmark.
- New interface to turn PSI on/off on a per cgroup level.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull PSI updates from Ingo Molnar:
- Various performance optimizations, resulting in a 4%-9% speedup in
the mmtests/config-scheduler-perfpipe micro-benchmark.
- New interface to turn PSI on/off on a per cgroup level.
* tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/psi: Per-cgroup PSI accounting disable/re-enable interface
sched/psi: Cache parent psi_group to speed up group iteration
sched/psi: Consolidate cgroup_psi()
sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure
sched/psi: Remove NR_ONCPU task accounting
sched/psi: Optimize task switch inside shared cgroups again
sched/psi: Move private helpers to sched/stats.h
sched/psi: Save percpu memory when !psi_cgroups_enabled
sched/psi: Don't create cgroup PSI files when psi_disabled
sched/psi: Fix periodic aggregation shut off
linux-next for a couple of months without, to my knowledge, any negative
reports (or any positive ones, come to that).
- Also the Maple Tree from Liam R. Howlett. An overlapping range-based
tree for vmas. It it apparently slight more efficient in its own right,
but is mainly targeted at enabling work to reduce mmap_lock contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
(https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com).
This has yet to be addressed due to Liam's unfortunately timed
vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down to
the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support
file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
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Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
Peter Zijlstra
Linus Torvalds
Mathieu Desnoyers
Yang Yang
Josh Poimboeuf
Nicholas Piggin
Valentin Schneider
wuchi
Hao Jia
Vincent Guittot
Waiman Long
Ingo Molnar
Yair Podemsky
Chengming Zhou
Zhen Lei
Matthew Wilcox (Oracle)
Kees Cook
Kefeng Wang
Tianchen Ding
Qais Yousef