The synchronous RCU-tasks grace-period-wait primitives invoke
schedule_timeout_idle() to give readers a chance to exit their
read-side critical sections. Unfortunately, this fails during early
boot on PREEMPT_RT because PREEMPT_RT relies solely on ksoftirqd to run
timer handlers. Because ksoftirqd cannot operate until its kthreads
are spawned, there is a brief period of time following scheduler
initialization where PREEMPT_RT cannot run the timer handlers that
schedule_timeout_idle() relies on, resulting in a hang.
To avoid this boot-time hang, this commit replaces schedule_timeout_idle()
with schedule_hrtimeout(), so that the timer expires in hardirq context.
This is ensures that the timer fires even on PREEMPT_RT throughout the
irqs-enabled portions of boot as well as during runtime.
The timer is set to expire between fract and fract + HZ / 2 jiffies in
order to align with any other timers that might expire during that time,
thus reducing the number of wakeups.
Note that RCU-tasks grace periods are infrequent, so the use of hrtimer
should be fine. In contrast, in common-case code, user of hrtimer
could result in performance issues.
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The main Tasks RCU quiescent state is voluntary context switch. However,
userspace execution is also a valid quiescent state, and is a valuable one
for userspace applications that spin repeatedly executing light-weight
non-sleeping system calls. Currently, such an application can delay a
Tasks RCU grace period for many tens of seconds.
This commit therefore enlists the aid of the scheduler-clock interrupt to
provide a Tasks RCU quiescent state when it interrupted a task executing
in userspace.
[ paulmck: Apply feedback from kernel test robot. ]
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Neil Spring <ntspring@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The waitqueue used by rcu_tasks_kthread() has always only one waiter.
With a guaranteed only one waiter, this can be replaced with rcuwait
which is smaller and simpler. With rcuwait based wake counterpart, the
irqwork function (call_rcu_tasks_iw_wakeup()) can be invoked hardirq
context because it is only a wake up and no sleeping locks are involved
(unlike the wait_queue_head).
As a side effect, this is also one piece of the puzzle to pass the RCU
selftest at early boot on PREEMPT_RT.
Replace wait_queue_head with rcuwait and let the irqwork run in hardirq
context on PREEMPT_RT.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
RCU-tasks stall-warning messages are printed after the grace period is ten
minutes old. Unfortunately, most of us will have rebooted the system in
response to an apparently-hung command long before the ten minutes is up,
and will thus see what looks to be a silent hang.
This commit therefore adds pr_info() messages that are printed earlier.
These should avoid being classified as errors, but should give impatient
users a hint. These are controlled by new rcupdate.rcu_task_stall_info
and rcupdate.rcu_task_stall_info_mult kernel-boot parameters. The former
defines the initial delay in jiffies (defaulting to 10 seconds) and the
latter defines the multiplier (defaulting to 3). Thus, by default, the
first message will appear 10 seconds into the RCU-tasks grace period,
the second 40 seconds in, and the third 160 seconds in. There would be
a fourth at 640 seconds in, but the stall warning message appears 600
seconds in, and once a stall warning is printed for a given grace period,
no further informational messages are printed.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
While booting secondary CPUs, cpus_read_[lock/unlock] is not keeping
online cpumask stable. The transient online mask results in below
calltrace.
[ 0.324121] CPU1: Booted secondary processor 0x0000000001 [0x410fd083]
[ 0.346652] Detected PIPT I-cache on CPU2
[ 0.347212] CPU2: Booted secondary processor 0x0000000002 [0x410fd083]
[ 0.377255] Detected PIPT I-cache on CPU3
[ 0.377823] CPU3: Booted secondary processor 0x0000000003 [0x410fd083]
[ 0.379040] ------------[ cut here ]------------
[ 0.383662] WARNING: CPU: 0 PID: 10 at kernel/workqueue.c:3084 __flush_work+0x12c/0x138
[ 0.384850] Modules linked in:
[ 0.385403] CPU: 0 PID: 10 Comm: rcu_tasks_rude_ Not tainted 5.17.0-rc3-v8+ #13
[ 0.386473] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
[ 0.387289] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 0.388308] pc : __flush_work+0x12c/0x138
[ 0.388970] lr : __flush_work+0x80/0x138
[ 0.389620] sp : ffffffc00aaf3c60
[ 0.390139] x29: ffffffc00aaf3d20 x28: ffffffc009c16af0 x27: ffffff80f761df48
[ 0.391316] x26: 0000000000000004 x25: 0000000000000003 x24: 0000000000000100
[ 0.392493] x23: ffffffffffffffff x22: ffffffc009c16b10 x21: ffffffc009c16b28
[ 0.393668] x20: ffffffc009e53861 x19: ffffff80f77fbf40 x18: 00000000d744fcc9
[ 0.394842] x17: 000000000000000b x16: 00000000000001c2 x15: ffffffc009e57550
[ 0.396016] x14: 0000000000000000 x13: ffffffffffffffff x12: 0000000100000000
[ 0.397190] x11: 0000000000000462 x10: ffffff8040258008 x9 : 0000000100000000
[ 0.398364] x8 : 0000000000000000 x7 : ffffffc0093c8bf4 x6 : 0000000000000000
[ 0.399538] x5 : 0000000000000000 x4 : ffffffc00a976e40 x3 : ffffffc00810444c
[ 0.400711] x2 : 0000000000000004 x1 : 0000000000000000 x0 : 0000000000000000
[ 0.401886] Call trace:
[ 0.402309] __flush_work+0x12c/0x138
[ 0.402941] schedule_on_each_cpu+0x228/0x278
[ 0.403693] rcu_tasks_rude_wait_gp+0x130/0x144
[ 0.404502] rcu_tasks_kthread+0x220/0x254
[ 0.405264] kthread+0x174/0x1ac
[ 0.405837] ret_from_fork+0x10/0x20
[ 0.406456] irq event stamp: 102
[ 0.406966] hardirqs last enabled at (101): [<ffffffc0093c8468>] _raw_spin_unlock_irq+0x78/0xb4
[ 0.408304] hardirqs last disabled at (102): [<ffffffc0093b8270>] el1_dbg+0x24/0x5c
[ 0.409410] softirqs last enabled at (54): [<ffffffc0081b80c8>] local_bh_enable+0xc/0x2c
[ 0.410645] softirqs last disabled at (50): [<ffffffc0081b809c>] local_bh_disable+0xc/0x2c
[ 0.411890] ---[ end trace 0000000000000000 ]---
[ 0.413000] smp: Brought up 1 node, 4 CPUs
[ 0.413762] SMP: Total of 4 processors activated.
[ 0.414566] CPU features: detected: 32-bit EL0 Support
[ 0.415414] CPU features: detected: 32-bit EL1 Support
[ 0.416278] CPU features: detected: CRC32 instructions
[ 0.447021] Callback from call_rcu_tasks_rude() invoked.
[ 0.506693] Callback from call_rcu_tasks() invoked.
This commit therefore fixes this issue by applying a single-CPU
optimization to the RCU Tasks Rude grace-period process. The key point
here is that the purpose of this RCU flavor is to force a schedule on
each online CPU since some past event. But the rcu_tasks_rude_wait_gp()
function runs in the context of the RCU Tasks Rude's grace-period kthread,
so there must already have been a context switch on the current CPU since
the call to either synchronize_rcu_tasks_rude() or call_rcu_tasks_rude().
So if there is only a single CPU online, RCU Tasks Rude's grace-period
kthread does not need to anything at all.
It turns out that the rcu_tasks_rude_wait_gp() function's call to
schedule_on_each_cpu() causes problems during early boot. During that
time, there is only one online CPU, namely the boot CPU. Therefore,
applying this single-CPU optimization fixes early-boot instances of
this problem.
Link: https://lore.kernel.org/lkml/20220210184319.25009-1-treasure4paddy@gmail.com/T/
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_spawn_gp_kthread() function is called as an early initcall, which
means that SMP initialization hasn't happened yet and only the boot CPU is
online. Therefore, create only the NOCB kthreads related to the boot CPU.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_spawn_gp_kthread() function is called as an early initcall,
which means that SMP initialization hasn't happened yet and only the
boot CPU is online. Therefore, create only the boost kthread for the
leaf node of the boot CPU.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_init() function is called way before SMP is initialized and
therefore only the boot CPU should be online at this stage.
Simplify the boot per-cpu initialization accordingly.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit moves the RCU nocb initialization witness within rcu_state
to consolidate RCU's global state.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The rcu_is_nocb_cpu() function is no longer used, so this commmit
removes it.
Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit instruments the acquisitions of the srcu_struct structure's
->lock, enabling the initiation of a transition from SRCU_SIZE_SMALL
to SRCU_SIZE_BIG when sufficient contention is experienced. The
instrumentation counts the number of trylock failures within the confines
of a single jiffy. If that number exceeds the value specified by the
srcutree.small_contention_lim kernel boot parameter (which defaults to
100), and if the value specified by the srcutree.convert_to_big kernel
boot parameter has the 0x10 bit set (defaults to 0), then a transition
will be automatically initiated.
By default, there will never be any transitions, so that none of the
srcu_struct structures ever gains an srcu_node array.
The useful values for srcutree.convert_to_big are:
0x00: Never convert.
0x01: Always convert at init_srcu_struct() time.
0x02: Convert when rcutorture prints its first round of statistics.
0x03: Decide conversion approach at boot given system size.
0x10: Convert if contention is encountered.
0x12: Convert if contention is encountered or when rcutorture prints
its first round of statistics, whichever comes first.
The value 0x11 acts the same as 0x01 because the conversion happens
before there is any chance of contention.
[ paulmck: Apply "static" feedback from kernel test robot. ]
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Once there are contention-initiated size transitions, it will be
possible for rcutorture to initiate a transition at the same time
as a contention-initiated transition. This commit therefore creates
a concurrency-safe helper function named srcu_transition_to_big() to
safely initiate size transitions.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds a comment explaining why an unprotected call to
list_add() from srcu_funnel_gp_start() can be safe. TL;DR: It is only
called during very early boot when we don't have no steeking concurrency!
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
When an srcu_struct structure is created (but not in a kernel module)
by DEFINE_SRCU() and friends, the per-CPU srcu_data structure is
statically allocated. In all other cases, that structure is obtained
from alloc_percpu(), in which case cleanup_srcu_struct() must invoke
free_percpu() on the resulting ->sda pointer in the srcu_struct pointer.
Which it does.
Except that it also invokes free_percpu() on the ->sda pointer
referencing the statically allocated per-CPU srcu_data structures.
Which free_percpu() is surprisingly OK with.
This commit nevertheless stops cleanup_srcu_struct() from freeing
statically allocated per-CPU srcu_data structures.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
You really shouldn't invoke srcu_torture_stats_print() after invoking
cleanup_srcu_struct(), but there is really no reason to get a
compiler-obfuscated per-CPU-variable NULL pointer dereference as the
diagnostic. This commit therefore checks for NULL ->sda and makes a
more polite console-message complaint in that case.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds an srcu_tree.convert_to_big kernel parameter that either
refuses to convert at all (0), converts immediately at init_srcu_struct()
time (1), or lets rcutorture convert it (2). An addition contention-based
dynamic conversion choice will be added, along with documentation.
[ paulmck: Apply callback-scanning feedback from Neeraj Upadhyay. ]
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
For configurations where snp node tree is not initialized at
init time (added in subsequent commits), srcu_funnel_gp_start()
and srcu_funnel_exp_start() can potential traverse and observe
the snp nodes' transient (uninitialized) states. This can potentially
happen, when init_srcu_struct_nodes() initialization of sdp->mynode
races with srcu_funnel_gp_start() and srcu_funnel_exp_start()
Consider the case below where srcu_funnel_gp_start() observes
sdp->mynode to be not NULL and uses an uninitialized sdp->grpmask
P1 P2
init_srcu_struct_nodes() void srcu_funnel_gp_start(...)
{
for_each_possible_cpu(cpu) {
...
sdp->mynode = &snp_first[...];
for (snp = sdp->mynode;...) struct srcu_node *snp_leaf =
smp_load_acquire(&sdp->mynode)
... if (snp_leaf) {
for (snp = snp_leaf; ...)
...
if (snp == snp_leaf)
snp->srcu_data_have_cbs[idx] |=
sdp->grpmask;
sdp->grpmask =
1 << (cpu - sdp->mynode->grplo);
}
}
Similarly, init_srcu_struct_nodes() and srcu_funnel_exp_start() can
race, where srcu_funnel_exp_start() could observe state of snp lock
before spin_lock_init().
P1 P2
init_srcu_struct_nodes() void srcu_funnel_exp_start(...)
{
srcu_for_each_node_breadth_first(ssp, snp) { for (; ...) {
spin_lock_...(snp, )
spin_lock_init(&ACCESS_PRIVATE(snp, lock));
...
}
for_each_possible_cpu(cpu) {
...
sdp->mynode = &snp_first[...];
To avoid these issues, ensure that snp node tree initialization is
complete i.e. after SRCU_SIZE_WAIT_BARRIER srcu_size_state is reached,
before traversing the tree. Given that srcu_funnel_gp_start() and
srcu_funnel_exp_start() are called within SRCU read side critical
sections, this check is safe, in the sense that all callbacks are
enqueued on CPU0 srcu_cblist until SRCU_SIZE_WAIT_CALL is entered,
and these read side critical sections (containing srcu_funnel_gp_start()
and srcu_funnel_exp_start()) need to complete, before SRCU_SIZE_WAIT_CALL
is reached.
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, tree SRCU relies on the srcu_node structures being initialized
at the same time that the srcu_struct itself is initialized, and thus
use the initial grace-period sequence number as the initial value for
the srcu_node structure's ->srcu_have_cbs[] and ->srcu_gp_seq_needed_exp
fields. Although this has a high probability of also working when the
srcu_node array is allocated and initialized at some random later time,
it would be better to avoid leaving such things to chance.
This commit therefore initializes these fields with 0x2, which is a
recognizable invalid value. It then adds the required checks for this
invalid value in order to avoid confusion on long-running kernels
(especially those on 32-bit systems) that allocate and initialize
srcu_node arrays late in life.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, srcu_funnel_gp_start() tests snp->srcu_have_cbs[idx] and then
separately assigns it to the snp_seq local variable. This commit does
the assignment earlier to simplify the code a bit. While in the area,
this commit also takes advantage of the 100-character line limit to put
the call to srcu_schedule_cbs_sdp() on a single line.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds the numeric and string version of ->srcu_size_state to
the Tree-SRCU-specific portion of the rcutorture output.
[ paulmck: Apply feedback from kernel test robot and Dan Carpenter. ]
[ quic_neeraju: Apply feedback from Jiapeng Chong. ]
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This is just dead code at the moment, and will be used once
the state-transition code is activated.
Because srcu_barrier() must be aware of transition before call_srcu(), the
state machine waits for an SRCU grace period before callbacks are queued
to the non-CPU-0 queues. This requres that portions of srcu_barrier()
be enclosed in an SRCU read-side critical section.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit shrinks the srcu_struct structure by converting its ->node
field from a fixed-size compile-time array to a pointer to a dynamically
allocated array. In kernels built with large values of NR_CPUS that boot
on systems with smaller numbers of CPUs, this can save significant memory.
[ paulmck: Apply kernel test robot feedback. ]
Reported-by: A cast of thousands
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit makes Tree SRCU able to operate without an snp_node
array, that is, when the srcu_data structures' ->mynode pointers
are NULL. This can result in high contention on the srcu_struct
structure's ->lock, but only when there are lots of call_srcu(),
synchronize_srcu(), and synchronize_srcu_expedited() calls.
Note that when there is no snp_node array, all SRCU callbacks use
CPU 0's callback queue. This is optimal in the common case of low
update-side load because it removes the need to search each CPU
for the single callback that made the grace period happen.
Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, the srcu_funnel_gp_start() walks its local variable snp up the
tree and reloads sdp->mynode whenever it is necessary to check whether
it is still at the leaf srcu_node level. This works, but is a bit more
obtuse than absolutely necessary. In addition, upcoming commits will
dynamically size srcu_struct structures, in which case sdp->mynode will
no longer necessarily be a constant, and this commit helps prepare for
that dynamic sizing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Currently, cleanup_srcu_struct() checks for a grace period in progress,
but it does not check for a grace period that has not yet started but
which might start at any time. Such a situation could result in a
use-after-free bug, so this commit adds a check for a grace period that
is needed but not yet started to cleanup_srcu_struct().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The seq argument is assigned to meta.seq twice, the second one is
redundant, remove it.
This patch also removes a redundant space in bpf_iter_link_attach().
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220410060020.307283-1-ytcoode@gmail.com
If CPUs on a node are offline at boot time, the number of nodes is
different when building affinity masks for present cpus and when building
affinity masks for possible cpus. This causes the following problem:
In the case that the number of vectors is less than the number of nodes
there are cases where bits of masks for present cpus are overwritten when
building masks for possible cpus.
Fix this by excluding CPUs, which are not part of the current build mask
(present/possible).
[ tglx: Massaged changelog and added comment ]
Fixes: b825921990 ("genirq/affinity: Spread IRQs to all available NUMA nodes")
Signed-off-by: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220331003309.10891-1-yamamoto.rei@jp.fujitsu.com
clocksource_verify_percpu() calls cpumask_weight() to check if any bit of a
given cpumask is set.
This can be done more efficiently with cpumask_empty() because
cpumask_empty() stops traversing the cpumask as soon as it finds first set
bit, while cpumask_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220210224933.379149-24-yury.norov@gmail.com
__irq_build_affinity_masks() calls cpumask_weight() to check if any bit of
a given cpumask is set.
This can be done more efficiently with cpumask_empty() because
cpumask_empty() stops traversing the cpumask as soon as it finds first set
bit, while cpumask_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220210224933.379149-22-yury.norov@gmail.com
When booting with maxcpus=<small number> (or even loading a driver
while most CPUs are offline), it is pretty easy to observe managed
affinities containing a mix of online and offline CPUs being passed
to the irqchip driver.
This means that the irqchip cannot trust the affinity passed down
from the core code, which is a bit annoying and requires (at least
in theory) all drivers to implement some sort of affinity narrowing.
In order to address this, always limit the cpumask to the set of
online CPUs.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220405185040.206297-3-maz@kernel.org
When booting with maxcpus=<small number>, interrupt controllers
such as the GICv3 ITS may not be able to satisfy the affinity of
some managed interrupts, as some of the HW resources are simply
not available.
The same thing happens when loading a driver using managed interrupts
while CPUs are offline.
In order to deal with this, do not try to activate such interrupt
if there is no online CPU capable of handling it. Instead, place
it in shutdown state. Once a capable CPU shows up, it will be
activated.
Reported-by: John Garry <john.garry@huawei.com>
Reported-by: David Decotigny <ddecotig@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/20220405185040.206297-2-maz@kernel.org
- A couple of fixes to event encoding on Sapphire Rapids
- Pass event caps of inherited events so that perf doesn't fail wrongly at fork()
- Add support for a new Raptor Lake CPU
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Merge tag 'perf_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Borislav Petkov:
- A couple of fixes to cgroup-related handling of perf events
- A couple of fixes to event encoding on Sapphire Rapids
- Pass event caps of inherited events so that perf doesn't fail wrongly
at fork()
- Add support for a new Raptor Lake CPU
* tag 'perf_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Always set cpuctx cgrp when enable cgroup event
perf/core: Fix perf_cgroup_switch()
perf/core: Use perf_cgroup_info->active to check if cgroup is active
perf/core: Don't pass task around when ctx sched in
perf/x86/intel: Update the FRONTEND MSR mask on Sapphire Rapids
perf/x86/intel: Don't extend the pseudo-encoding to GP counters
perf/core: Inherit event_caps
perf/x86/uncore: Add Raptor Lake uncore support
perf/x86/msr: Add Raptor Lake CPU support
perf/x86/cstate: Add Raptor Lake support
perf/x86: Add Intel Raptor Lake support
the local_lock_* macros back to inline functions
- A couple of fixes to static call insn patching
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Merge tag 'locking_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Borislav Petkov:
- Allow the compiler to optimize away unused percpu accesses and change
the local_lock_* macros back to inline functions
- A couple of fixes to static call insn patching
* tag 'locking_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "mm/page_alloc: mark pagesets as __maybe_unused"
Revert "locking/local_lock: Make the empty local_lock_*() function a macro."
x86/percpu: Remove volatile from arch_raw_cpu_ptr().
static_call: Remove __DEFINE_STATIC_CALL macro
static_call: Properly initialise DEFINE_STATIC_CALL_RET0()
static_call: Don't make __static_call_return0 static
x86,static_call: Fix __static_call_return0 for i386
- Two fixes for the new forceidle balancer
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Merge tag 'sched_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Borislav Petkov:
- Use the correct static key checking primitive on the IRQ exit path
- Two fixes for the new forceidle balancer
* tag 'sched_urgent_for_v5.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
entry: Fix compile error in dynamic_irqentry_exit_cond_resched()
sched: Teach the forced-newidle balancer about CPU affinity limitation.
sched/core: Fix forceidle balancing
Fixes the following W=1 kernel build warning:
kernel/time/tick-sched.c:1563: warning: This comment starts with '/**',
but isn't a kernel-doc comment.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220214084739.63228-1-jiapeng.chong@linux.alibaba.com
While running some testing on code that happened to allow the variable
tick_nohz_full_running to get set but with no "possible" NOHZ cores to
back up that setting, this warning triggered:
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
WARN_ON(tick_nohz_full_running);
The console was overwhemled with an endless stream of one WARN per tick
per core and there was no way to even see what was going on w/o using a
serial console to capture it and then trace it back to this.
Change it to WARN_ON_ONCE().
Fixes: 08ae95f4fd ("nohz_full: Allow the boot CPU to be nohz_full")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211206145950.10927-3-paul.gortmaker@windriver.com
The level granularity round up of calc_index() does:
(x + (1 << n)) >> n
which is obviously equivalent to
(x >> n) + 1
but compilers can't figure that out despite the fact that the input range
is known to not cause an overflow. It's neither intuitive to read.
Just write out the obvious.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/87h778j46c.ffs@tglx
When base::next_expiry_recalc is not initialized to false during cpu
bringup in HOTPLUG_CPU and is accidently true and no timer is queued in the
meantime, the loop through the wheel to find __next_timer_interrupt() might
be done for nothing.
Therefore initialize base::next_expiry_recalc to false in
timers_prepare_cpu().
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220405191732.7438-2-anna-maria@linutronix.de
When the timer base is empty, base::next_expiry is set to base::clk +
NEXT_TIMER_MAX_DELTA and base::next_expiry_recalc is false. When no timer
is queued until jiffies reaches base::next_expiry value, the warning for
not finding any expired timer and base::next_expiry_recalc is false in
__run_timers() triggers.
To prevent triggering the warning in this valid scenario
base::timers_pending needs to be added to the warning condition.
Fixes: 31cd0e119d ("timers: Recalculate next timer interrupt only when necessary")
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220405191732.7438-3-anna-maria@linutronix.de
Daniel Borkmann says:
====================
pull-request: bpf-next 2022-04-09
We've added 63 non-merge commits during the last 9 day(s) which contain
a total of 68 files changed, 4852 insertions(+), 619 deletions(-).
The main changes are:
1) Add libbpf support for USDT (User Statically-Defined Tracing) probes.
USDTs are an abstraction built on top of uprobes, critical for tracing
and BPF, and widely used in production applications, from Andrii Nakryiko.
2) While Andrii was adding support for x86{-64}-specific logic of parsing
USDT argument specification, Ilya followed-up with USDT support for s390
architecture, from Ilya Leoshkevich.
3) Support name-based attaching for uprobe BPF programs in libbpf. The format
supported is `u[ret]probe/binary_path:[raw_offset|function[+offset]]`, e.g.
attaching to libc malloc can be done in BPF via SEC("uprobe/libc.so.6:malloc")
now, from Alan Maguire.
4) Various load/store optimizations for the arm64 JIT to shrink the image
size by using arm64 str/ldr immediate instructions. Also enable pointer
authentication to verify return address for JITed code, from Xu Kuohai.
5) BPF verifier fixes for write access checks to helper functions, e.g.
rd-only memory from bpf_*_cpu_ptr() must not be passed to helpers that
write into passed buffers, from Kumar Kartikeya Dwivedi.
6) Fix overly excessive stack map allocation for its base map structure and
buckets which slipped-in from cleanups during the rlimit accounting removal
back then, from Yuntao Wang.
7) Extend the unstable CT lookup helpers for XDP and tc/BPF to report netfilter
connection tracking tuple direction, from Lorenzo Bianconi.
8) Improve bpftool dump to show BPF program/link type names, Milan Landaverde.
9) Minor cleanups all over the place from various others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (63 commits)
bpf: Fix excessive memory allocation in stack_map_alloc()
selftests/bpf: Fix return value checks in perf_event_stackmap test
selftests/bpf: Add CO-RE relos into linked_funcs selftests
libbpf: Use weak hidden modifier for USDT BPF-side API functions
libbpf: Don't error out on CO-RE relos for overriden weak subprogs
samples, bpf: Move routes monitor in xdp_router_ipv4 in a dedicated thread
libbpf: Allow WEAK and GLOBAL bindings during BTF fixup
libbpf: Use strlcpy() in path resolution fallback logic
libbpf: Add s390-specific USDT arg spec parsing logic
libbpf: Make BPF-side of USDT support work on big-endian machines
libbpf: Minor style improvements in USDT code
libbpf: Fix use #ifdef instead of #if to avoid compiler warning
libbpf: Potential NULL dereference in usdt_manager_attach_usdt()
selftests/bpf: Uprobe tests should verify param/return values
libbpf: Improve string parsing for uprobe auto-attach
libbpf: Improve library identification for uprobe binary path resolution
selftests/bpf: Test for writes to map key from BPF helpers
selftests/bpf: Test passing rdonly mem to global func
bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access
bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access
...
====================
Link: https://lore.kernel.org/r/20220408231741.19116-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of the
allocated memory for 'smap' is never used after the memlock accounting was
removed, thus get rid of it.
[ Note, Daniel:
Commit b936ca643a ("bpf: rework memlock-based memory accounting for maps")
moved `cost += n_buckets * (value_size + sizeof(struct stack_map_bucket))`
up and therefore before the bpf_map_area_alloc() allocation, sigh. In a later
step commit c85d69135a ("bpf: move memory size checks to bpf_map_charge_init()"),
and the overflow checks of `cost >= U32_MAX - PAGE_SIZE` moved into
bpf_map_charge_init(). And then 370868107b ("bpf: Eliminate rlimit-based
memory accounting for stackmap maps") finally removed the bpf_map_charge_init().
Anyway, the original code did the allocation same way as /after/ this fix. ]
Fixes: b936ca643a ("bpf: rework memlock-based memory accounting for maps")
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220407130423.798386-1-ytcoode@gmail.com
Unlike regular VMs, TDX guests use the firmware hand-off wakeup method
to wake up the APs during the boot process. This wakeup model uses a
mailbox to communicate with firmware to bring up the APs. As per the
design, this mailbox can only be used once for the given AP, which means
after the APs are booted, the same mailbox cannot be used to
offline/online the given AP. More details about this requirement can be
found in Intel TDX Virtual Firmware Design Guide, sec titled "AP
initialization in OS" and in sec titled "Hotplug Device".
Since the architecture does not support any method of offlining the
CPUs, disable CPU hotplug support in the kernel.
Since this hotplug disable feature can be re-used by other VM guests,
add a new CC attribute CC_ATTR_HOTPLUG_DISABLED and use it to disable
the hotplug support.
Attempt to offline CPU will fail with -EOPNOTSUPP.
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20220405232939.73860-25-kirill.shutemov@linux.intel.com
Alexei Starovoitov says:
====================
pull-request: bpf 2022-04-06
We've added 8 non-merge commits during the last 8 day(s) which contain
a total of 9 files changed, 139 insertions(+), 36 deletions(-).
The main changes are:
1) rethook related fixes, from Jiri and Masami.
2) Fix the case when tracing bpf prog is attached to struct_ops, from Martin.
3) Support dual-stack sockets in bpf_tcp_check_syncookie, from Maxim.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
bpf: Adjust bpf_tcp_check_syncookie selftest to test dual-stack sockets
bpf: Support dual-stack sockets in bpf_tcp_check_syncookie
bpf: selftests: Test fentry tracing a struct_ops program
bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT
rethook: Fix to use WRITE_ONCE() for rethook:: Handler
selftests/bpf: Fix warning comparing pointer to 0
bpf: Fix sparse warnings in kprobe_multi_resolve_syms
bpftool: Explicit errno handling in skeletons
====================
Link: https://lore.kernel.org/r/20220407031245.73026-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This moves ftrace_enabled to trace/ftrace.c.
We move sysctls to places where features actually belong to improve
the readability of the code and reduce the risk of code merge conflicts.
At the same time, the proc-sysctl maintainers do not want to know what
sysctl knobs you wish to add for your owner piece of code, we just care
about the core logic.
Signed-off-by: Wei Xiao <xiaowei66@huawei.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.
All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the real_root_dev sysctl to its own file,
kernel/do_mount_initrd.c.
Signed-off-by: tangmeng <tangmeng@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.
All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the delayacct sysctl to its own file,
kernel/delayacct.c.
Signed-off-by: tangmeng <tangmeng@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
