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When the watchdog determines that the current soft lockup is due to an
interrupt storm based on CPU utilization, reporting the most frequent
interrupts could be good enough for further troubleshooting.
Below is an example of interrupt storm. The call tree does not provide
useful information, but analyzing which interrupt caused the soft lockup by
comparing the counts of interrupts during the lockup period allows to
identify the culprit.
[ 638.870231] watchdog: BUG: soft lockup - CPU#9 stuck for 26s! [swapper/9:0]
[ 638.870825] CPU#9 Utilization every 4s during lockup:
[ 638.871194] #1: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.871652] #2: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.872107] #3: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.872563] #4: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.873018] #5: 0% system, 0% softirq, 100% hardirq, 0% idle
[ 638.873494] CPU#9 Detect HardIRQ Time exceeds 50%. Most frequent HardIRQs:
[ 638.873994] #1: 330945 irq#7
[ 638.874236] #2: 31 irq#82
[ 638.874493] #3: 10 irq#10
[ 638.874744] #4: 2 irq#89
[ 638.874992] #5: 1 irq#102
...
[ 638.875313] Call trace:
[ 638.875315] __do_softirq+0xa8/0x364
Signed-off-by: Bitao Hu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Liu Song <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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The following softlockup is caused by interrupt storm, but it cannot be
identified from the call tree. Because the call tree is just a snapshot
and doesn't fully capture the behavior of the CPU during the soft lockup.
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
...
Call trace:
__do_softirq+0xa0/0x37c
__irq_exit_rcu+0x108/0x140
irq_exit+0x14/0x20
__handle_domain_irq+0x84/0xe0
gic_handle_irq+0x80/0x108
el0_irq_naked+0x50/0x58
Therefore, it is necessary to report CPU utilization during the
softlockup_threshold period (report once every sample_period, for a total
of 5 reportings), like this:
watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921]
CPU#28 Utilization every 4s during lockup:
#1: 0% system, 0% softirq, 100% hardirq, 0% idle
#2: 0% system, 0% softirq, 100% hardirq, 0% idle
#3: 0% system, 0% softirq, 100% hardirq, 0% idle
#4: 0% system, 0% softirq, 100% hardirq, 0% idle
#5: 0% system, 0% softirq, 100% hardirq, 0% idle
...
This is helpful in determining whether an interrupt storm has occurred or
in identifying the cause of the softlockup. The criteria for determination
are as follows:
a. If the hardirq utilization is high, then interrupt storm should be
considered and the root cause cannot be determined from the call tree.
b. If the softirq utilization is high, then the call might not necessarily
point at the root cause.
c. If the system utilization is high, then analyzing the root
cause from the call tree is possible in most cases.
The mechanism requires a considerable amount of global storage space
when configured for the maximum number of CPUs. Therefore, adding a
SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob that defaults to "yes"
if the max number of CPUs is <= 128.
Signed-off-by: Bitao Hu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Reviewed-by: Liu Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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show_interrupts() unconditionally accumulates the per CPU interrupt
statistics to determine whether an interrupt was ever raised.
This can be avoided for all interrupts which are not strictly per CPU
and not of type NMI because those interrupts provide already an
accumulated counter. The required logic is already implemented in
kstat_irqs().
Split the inner access logic out of kstat_irqs() and use it for
kstat_irqs() and show_interrupts() to avoid the accumulation loop
when possible.
Originally-by: Thomas Gleixner <[email protected]>
Signed-off-by: Bitao Hu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Liu Song <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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The soft lockup detector lacks a mechanism to identify interrupt storms as
root cause of a lockup. To enable this the detector needs a mechanism to
snapshot the interrupt count statistics on a CPU when the detector observes
a potential lockup scenario and compare that against the interrupt count
when it warns about the lockup later on. The number of interrupts in that
period give a hint whether the lockup might have been caused by an interrupt
storm.
Instead of having extra storage in the lockup detector and accessing the
internals of the interrupt descriptor directly, add a snapshot member to
the per CPU irq_desc::kstat_irq structure and provide interfaces to take a
snapshot of all interrupts on the current CPU and to retrieve the delta of
a specific interrupt later on.
Originally-by: Thomas Gleixner <[email protected]>
Signed-off-by: Bitao Hu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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The irq_desc::kstat_irqs member is a per-CPU variable of type int, which is
only capable of counting. A snapshot mechanism for interrupt statistics
will be added soon, which requires an additional variable to store the
snapshot.
To facilitate expansion, convert kstat_irqs here to a struct containing
only the count.
Originally-by: Thomas Gleixner <[email protected]>
Signed-off-by: Bitao Hu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Otherwise the compiler will be unhappy if they go unused,
which they do on allnoconfigs.
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Kyle Huey <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Returning zero from a BPF program attached to a perf event already
suppresses any data output. Return early from __perf_event_overflow() in
this case so it will also suppress event_limit accounting, SIGTRAP
generation, and F_ASYNC signalling.
Signed-off-by: Kyle Huey <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Song Liu <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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To ultimately allow BPF programs attached to perf events to completely
suppress all of the effects of a perf event overflow (rather than just the
sample output, as they do today), call bpf_overflow_handler() from
__perf_event_overflow() directly rather than modifying struct perf_event's
overflow_handler. Return the BPF program's return value from
bpf_overflow_handler() so that __perf_event_overflow() knows how to
proceed. Remove the now unnecessary orig_overflow_handler from struct
perf_event.
This patch is solely a refactoring and results in no behavior change.
Suggested-by: Namhyung Kim <[email protected]>
Signed-off-by: Kyle Huey <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Acked-by: Song Liu <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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This will allow __perf_event_overflow() (which is independent of
CONFIG_BPF_SYSCALL) to call bpf_overflow_handler().
Signed-off-by: Kyle Huey <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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This will allow __perf_event_overflow() to call bpf_overflow_handler().
Signed-off-by: Kyle Huey <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Use try_cmpxchg(*ptr, &old, new) instead of
cmpxchg(*ptr, old, new) == old in qspinlock_paravirt.h
x86 CMPXCHG instruction returns success in ZF flag, so
this change saves a compare after cmpxchg.
No functional change intended.
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Waiman Long <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Replace this pattern in trylock_clear_pending():
cmpxchg_acquire(*ptr, old, new) == old
... with the simpler and faster:
try_cmpxchg_acquire(*ptr, &old, new)
The x86 CMPXCHG instruction returns success in the ZF flag, so this change
saves a compare after the CMPXCHG.
Also change the return type of the function to bool and streamline
the control flow in the _Q_PENDING_BITS == 8 variant a bit.
No functional change intended.
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Waiman Long <[email protected]>
Reviewed-by: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that
even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY
might see the occasional preemption, and that this preemption just might
happen within a trampoline.
Therefore, update ftrace_shutdown() to invoke synchronize_rcu_tasks()
based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION.
[ paulmck: Apply Steven Rostedt feedback. ]
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Ankur Arora <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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The advent of CONFIG_PREEMPT_AUTO, AKA lazy preemption, will mean that
even kernels built with CONFIG_PREEMPT_NONE or CONFIG_PREEMPT_VOLUNTARY
might see the occasional preemption, and that this preemption just might
happen within a trampoline.
Therefore, update bpf_tramp_image_put() to choose call_rcu_tasks()
based on CONFIG_TASKS_RCU instead of CONFIG_PREEMPTION.
This change might enable further simplifications, but the goal of this
effort is to make the code safe, not necessarily optimal.
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Ankur Arora <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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With the demise of the .change_pte() MMU notifier callback, there is no
notification happening in set_pte_at_notify(). It is a synonym of
set_pte_at() and can be replaced with it.
Signed-off-by: Paolo Bonzini <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-ID: <[email protected]>
Acked-by: Andrew Morton <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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As the old padata code can execute in softirq context, disable
softirqs for the new padata_do_mutithreaded code too as otherwise
lockdep will get antsy.
Reported-by: [email protected]
Signed-off-by: Herbert Xu <[email protected]>
Acked-by: Daniel Jordan <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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The "buffer_percent" logic that is used by the ring buffer splice code to
only wake up the tasks when there's no data after the buffer is filled to
the percentage of the "buffer_percent" file is dependent on three
variables that determine the amount of data that is in the ring buffer:
1) pages_read - incremented whenever a new sub-buffer is consumed
2) pages_lost - incremented every time a writer overwrites a sub-buffer
3) pages_touched - incremented when a write goes to a new sub-buffer
The percentage is the calculation of:
(pages_touched - (pages_lost + pages_read)) / nr_pages
Basically, the amount of data is the total number of sub-bufs that have been
touched, minus the number of sub-bufs lost and sub-bufs consumed. This is
divided by the total count to give the buffer percentage. When the
percentage is greater than the value in the "buffer_percent" file, it
wakes up splice readers waiting for that amount.
It was observed that over time, the amount read from the splice was
constantly decreasing the longer the trace was running. That is, if one
asked for 60%, it would read over 60% when it first starts tracing, but
then it would be woken up at under 60% and would slowly decrease the
amount of data read after being woken up, where the amount becomes much
less than the buffer percent.
This was due to an accounting of the pages_touched incrementation. This
value is incremented whenever a writer transfers to a new sub-buffer. But
the place where it was incremented was incorrect. If a writer overflowed
the current sub-buffer it would go to the next one. If it gets preempted
by an interrupt at that time, and the interrupt performs a trace, it too
will end up going to the next sub-buffer. But only one should increment
the counter. Unfortunately, that was not the case.
Change the cmpxchg() that does the real switch of the tail-page into a
try_cmpxchg(), and on success, perform the increment of pages_touched. This
will only increment the counter once for when the writer moves to a new
sub-buffer, and not when there's a race and is incremented for when a
writer and its preempting writer both move to the same new sub-buffer.
Link: https://lore.kernel.org/linux-trace-kernel/[email protected]
Cc: [email protected]
Cc: Mathieu Desnoyers <[email protected]>
Fixes: 2c2b0a78b3739 ("ring-buffer: Add percentage of ring buffer full to wake up reader")
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
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When CONFIG_PERF_EVENTS, a 'make W=1' build produces a warning about the
unused ftrace_event_id_fops variable:
kernel/trace/trace_events.c:2155:37: error: 'ftrace_event_id_fops' defined but not used [-Werror=unused-const-variable=]
2155 | static const struct file_operations ftrace_event_id_fops = {
Hide this in the same #ifdef as the reference to it.
Link: https://lore.kernel.org/linux-trace-kernel/[email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Zheng Yejian <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Ajay Kaher <[email protected]>
Cc: Jinjie Ruan <[email protected]>
Cc: Clément Léger <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: "Tzvetomir Stoyanov (VMware)" <[email protected]>
Fixes: 620a30e97feb ("tracing: Don't pass file_operations array to event_create_dir()")
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
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Fix FTRACE_RECORD_RECURSION_SIZE entry, replace tab with
a space character. It helps Kconfig parsers to read file
without error.
Link: https://lore.kernel.org/linux-trace-kernel/[email protected]
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Fixes: 773c16705058 ("ftrace: Add recording of functions that caused recursion")
Signed-off-by: Prasad Pandit <[email protected]>
Reviewed-by: Randy Dunlap <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
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Cross-merge networking fixes after downstream PR.
Conflicts:
net/unix/garbage.c
47d8ac011fe1 ("af_unix: Fix garbage collector racing against connect()")
4090fa373f0e ("af_unix: Replace garbage collection algorithm.")
Adjacent changes:
drivers/net/ethernet/broadcom/bnxt/bnxt.c
faa12ca24558 ("bnxt_en: Reset PTP tx_avail after possible firmware reset")
b3d0083caf9a ("bnxt_en: Support RSS contexts in ethtool .{get|set}_rxfh()")
drivers/net/ethernet/broadcom/bnxt/bnxt_ulp.c
7ac10c7d728d ("bnxt_en: Fix possible memory leak in bnxt_rdma_aux_device_init()")
194fad5b2781 ("bnxt_en: Refactor bnxt_rdma_aux_device_init/uninit functions")
drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
958f56e48385 ("net/mlx5e: Un-expose functions in en.h")
49e6c9387051 ("net/mlx5e: RSS, Block XOR hash with over 128 channels")
Signed-off-by: Jakub Kicinski <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fix from Rafael Wysocki:
"Fix the suspend-to-idle core code to guarantee that timers queued on
CPUs other than the one that has first left the idle state, which
should expire directly after resume, will be handled (Anna-Maria
Behnsen)"
* tag 'pm-6.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: s2idle: Make sure CPUs will wakeup directly on resume
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Using of devm API leads to a certain order of releasing resources.
So all dependent resources which are not devm-wrapped should be deleted
with respect to devm-release order. Mutex is one of such objects that
often is bound to other resources and has no own devm wrapping.
Since mutex_destroy() actually does nothing in non-debug builds
frequently calling mutex_destroy() is just ignored which is safe for now
but wrong formally and can lead to a problem if mutex_destroy() will be
extended so introduce devm_mutex_init().
Suggested-by: Christophe Leroy <[email protected]>
Signed-off-by: George Stark <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Reviewed-by: Marek Behún <[email protected]>
Acked-by: Waiman Long <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lee Jones <[email protected]>
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Currently, if a Kconfig option depends on TASKS_RCU, it conditionally does
"select TASKS_RCU if PREEMPTION". This works, but requires any change in
this enablement logic to be replicated across all such "select" clauses.
A new NEED_TASKS_RCU Kconfig option has been created to allow this
enablement logic to be in one place in kernel/rcu/Kconfig.
Therefore, select the new NEED_TASKS_RCU Kconfig option instead of the
old TASKS_RCU option.
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: <[email protected]>
Cc: Ankur Arora <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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The synchronize_rcu() call is going to be reworked, thus
this patch adds dedicated fields into the rcu_state structure.
Reviewed-by: Paul E. McKenney <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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Deduplicate ->read() callbacks of bin_attributes which are backed by a
simple buffer in memory:
Use the newly introduced sysfs_bin_attr_simple_read() helper instead,
either by referencing it directly or by declaring such bin_attributes
with BIN_ATTR_SIMPLE_RO() or BIN_ATTR_SIMPLE_ADMIN_RO().
Aside from a reduction of LoC, this shaves off a few bytes from vmlinux
(304 bytes on an x86_64 allyesconfig).
No functional change intended.
Signed-off-by: Lukas Wunner <[email protected]>
Acked-by: Zhi Wang <[email protected]>
Acked-by: Michael Ellerman <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Link: https://lore.kernel.org/r/92ee0a0e83a5a3f3474845db6c8575297698933a.1712410202.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Use atomic_try_cmpxchg_relaxed(*ptr, &old, new) instead of
atomic_cmpxchg_relaxed (*ptr, old, new) == old in xchg_tail().
x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after CMPXCHG.
No functional change intended.
Since this code requires NR_CPUS >= 16k, I have tested it
by unconditionally setting _Q_PENDING_BITS to 1 in
<asm-generic/qspinlock_types.h>.
Signed-off-by: Uros Bizjak <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Waiman Long <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Add a generic function console_replay_all() for replaying
the kernel log on consoles, in any context. It would allow
viewing the logs on an unresponsive terminal via sysrq.
Reuse the existing code from console_flush_on_panic() for
resetting the sequence numbers, by introducing a new helper
function __console_rewind_all(). It is safe to be called
under console_lock().
Try to acquire lock on the console subsystem without waiting.
If successful, reset the sequence number to oldest available
record on all consoles and call console_unlock() which will
automatically flush the messages to the consoles.
Suggested-by: John Ogness <[email protected]>
Suggested-by: Petr Mladek <[email protected]>
Signed-off-by: Shimoyashiki Taichi <[email protected]>
Reviewed-by: John Ogness <[email protected]>
Signed-off-by: Sreenath Vijayan <[email protected]>
Link: https://lore.kernel.org/r/90ee131c643a5033d117b556c0792de65129d4c3.1710220326.git.sreenath.vijayan@sony.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Add bpf_link support for sk_msg and sk_skb programs. We have an
internal request to support bpf_link for sk_msg programs so user
space can have a uniform handling with bpf_link based libbpf
APIs. Using bpf_link based libbpf API also has a benefit which
makes system robust by decoupling prog life cycle and
attachment life cycle.
Reviewed-by: John Fastabend <[email protected]>
Signed-off-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
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When unloading a module, its state is changing MODULE_STATE_LIVE ->
MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
a time. `is_module_text_address()` and `__module_text_address()`
works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
If we use `is_module_text_address()` and `__module_text_address()`
separately, there is a chance that the first one is succeeded but the
next one is failed because module->state becomes MODULE_STATE_UNFORMED
between those operations.
In `check_kprobe_address_safe()`, if the second `__module_text_address()`
is failed, that is ignored because it expected a kernel_text address.
But it may have failed simply because module->state has been changed
to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
non-exist module text address (use-after-free).
To fix this problem, we should not use separated `is_module_text_address()`
and `__module_text_address()`, but use only `__module_text_address()`
once and do `try_module_get(module)` which is only available with
MODULE_STATE_LIVE.
Link: https://lore.kernel.org/all/[email protected]/
Fixes: 28f6c37a2910 ("kprobes: Forbid probing on trampoline and BPF code areas")
Cc: [email protected]
Signed-off-by: Zheng Yejian <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
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Initialize cpu_mitigations to CPU_MITIGATIONS_OFF if the kernel is built
with CONFIG_SPECULATION_MITIGATIONS=n, as the help text quite clearly
states that disabling SPECULATION_MITIGATIONS is supposed to turn off all
mitigations by default.
│ If you say N, all mitigations will be disabled. You really
│ should know what you are doing to say so.
As is, the kernel still defaults to CPU_MITIGATIONS_AUTO, which results in
some mitigations being enabled in spite of SPECULATION_MITIGATIONS=n.
Fixes: f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Daniel Sneddon <[email protected]>
Cc: [email protected]
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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tick_do_timer_cpu is used lockless to check which CPU needs to take care
of the per tick timekeeping duty. This is done to avoid a thundering
herd problem on jiffies_lock.
The read and writes are not annotated so KCSAN complains about data races:
BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event
write to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 26:
tick_nohz_idle_stop_tick+0x3b1/0x4a0
do_idle+0x1e3/0x250
read to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 16:
tick_nohz_next_event+0xe7/0x1e0
tick_nohz_get_sleep_length+0xa7/0xe0
menu_select+0x82/0xb90
cpuidle_select+0x44/0x60
do_idle+0x1c2/0x250
value changed: 0x0000001a -> 0xffffffff
Annotate them with READ/WRITE_ONCE() to document the intentional data race.
Reported-by: Mirsad Todorovac <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: Sean Anderson <[email protected]>
Link: https://lore.kernel.org/r/87cyqy7rt3.ffs@tglx
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In perf_adjust_freq_unthr_context(), it first starts the event and then
stop unnecessarily to adjust the sampling frequency if the event is
throttled.
For a throttled non-frequency event, it doesn't have a freq so no need
to adjust. Just starting the event would be ok.
For a frequency event, whether it's throttled or not, it needs to stop
before adjusting the frequency. That means it should not start the
even if it was throttled. I tried to skip calling the stop callback,
but it didn't work well since the event count might not be up to date.
It should call the stop callback with PERF_EF_UPDATE anyway.
However not calling start would prevent unnecessary MSR accesses (which
can be costly) for already stopped events as stop state is saved in the
hw config.
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Ian Rogers <[email protected]>
Reviewed-by: Kan Liang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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It was unnecessarily disabling and enabling PMUs for each event. It
should be done at PMU level. Add pmu_ctx->nr_freq counter to check it
at each PMU. As PMU context has separate active lists for pinned group
and flexible group, factor out a new function to do the job.
Another minor optimization is that it can skip PMUs w/ CAP_NO_INTERRUPT
even if it needs to unthrottle sampling events.
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: Mingwei Zhang <[email protected]>
Reviewed-by: Ian Rogers <[email protected]>
Reviewed-by: Kan Liang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Support atomics in bpf_arena that can be JITed as a single x86 instruction.
Instructions that are JITed as loops are not supported at the moment,
since they require more complex extable and loop logic.
JITs can choose to do smarter things with bpf_jit_supports_insn().
Like arm64 may decide to support all bpf atomics instructions
when emit_lse_atomic is available and none in ll_sc mode.
bpf_jit_supports_percpu_insn(), bpf_jit_supports_ptr_xchg() and
other such callbacks can be replaced with bpf_jit_supports_insn()
in the future.
Signed-off-by: Alexei Starovoitov <[email protected]>
Acked-by: Eduard Zingerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin KaFai Lau <[email protected]>
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If add_preferred_console() is not called early in setup_console(), we can
end up having register_console() call try_enable_default_console() before a
console device has called add_preferred_console().
Let's set console_set_on_cmdline flag in console_setup() to prevent this
from happening.
Signed-off-by: Tony Lindgren <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Currently console_setup() tries to make a console index out of any digits
passed in the kernel command line for console. In the DEVNAME:0.0 case,
the name can contain a device IO address, so bail out on console names
with a ':'.
Signed-off-by: Tony Lindgren <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Driver subsystems may need to translate the preferred console name to the
character device name used. We already do some of this in console_setup()
with a few hardcoded names, but that does not scale well.
The console options are parsed early in console_setup(), and the consoles
are added with __add_preferred_console(). At this point we don't know much
about the character device names and device drivers getting probed.
To allow driver subsystems to set up a preferred console, let's save the
kernel command line console options. To add a preferred console from a
driver subsystem with optional character device name translation, let's
add a new function add_preferred_console_match().
This allows the serial core layer to support console=DEVNAME:0.0 style
hardware based addressing in addition to the current console=ttyS0 style
naming. And we can start moving console_setup() character device parsing
to the driver subsystem specific code.
We use a separate array from the console_cmdline array as the character
device name and index may be unknown at the console_setup() time. And
eventually there's no need to call __add_preferred_console() until the
subsystem is ready to handle the console.
Adding the console name in addition to the character device name, and a
flag for an added console, could be added to the struct console_cmdline.
And the console_cmdline array handling could be modified accordingly. But
that complicates things compared saving the console options, and then
adding the consoles when the subsystems handling the consoles are ready.
Co-developed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Currently, if a Kconfig option depends on TASKS_RCU, it conditionally does
"select TASKS_RCU if PREEMPTION". This works, but requires any change in
this enablement logic to be replicated across all such "select" clauses.
A new NEED_TASKS_RCU Kconfig option has been created to allow this
enablement logic to be in one place in kernel/rcu/Kconfig.
Therefore, make BPF select the new NEED_TASKS_RCU Kconfig option.
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: <[email protected]>
Cc: Ankur Arora <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Steven Rostedt <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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Currently, all waits for grace periods sleep at TASK_UNINTERRUPTIBLE,
regardless of RCU flavor. This has worked well, but there have been
cases where a longer-than-average Tasks RCU grace period has triggered
softlockup splats, many of them, before the Tasks RCU CPU stall warning
appears. These softlockup splats unnecessarily consume console bandwidth
and complicate diagnosis of the underlying problem. Plus a long but not
pathologically long Tasks RCU grace period might trigger a few softlockup
splats before completing normally, which generates noise for no good
reason.
This commit therefore causes Tasks RCU grace periods to sleep at TASK_IDLE
priority. If there really is a persistent problem, the eventual Tasks
RCU CPU stall warning will flag it, and without the extra noise.
Reported-by: Breno Leitao <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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It turns out that only one CPU at a time will ever invoke
rcu_torture_pipe_update_one() on a given rcu_torture structure.
This commit therefore adds three ASSERT_EXCLUSIVE_WRITER() calls
to enlist KCSAN's aid in checking this.
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Linus Torvalds <[email protected]>
Reviewed-by: Joel Fernandes (Google) <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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If a callback flood prevents grace period from completing, rcutorture
does a WARN_ON(). Avoiding this WARN_ON() currently requires that at
least three grace periods elapse during an eight-second callback-flood
interval. Unfortunately, the current debug information does not include
anything about the grace-period state. This commit therefore adds a
call to cur_ops->gp_kthread_dbg(), if this function pointer is non-NULL.
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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This commit adds the number of online CPUs to the state dump following
an unsuccesful callback-flood test.
Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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There is some indications that rcu_softirq_qs() might be more generally
used than anticipated. This commit therefore adds some lockdep assertions
and some cautionary tales in a new kernel-doc header.
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Yan Zhai <[email protected]>
Cc: <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
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Per filesystems/sysfs.rst, show() should only use sysfs_emit() or
sysfs_emit_at() when formatting the value to be returned to user space.
coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Per filesystems/sysfs.rst, show() should only use sysfs_emit() or
sysfs_emit_at() when formatting the value to be returned to user space.
coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().
Signed-off-by: Li Zhijian <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
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Signed-off-by: Ingo Molnar <[email protected]>
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This commit add missed destroy_work_on_stack() operations for
dead_work.work.
Signed-off-by: Zqiang <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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Since commit 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside
get_online_cpus()"), cpuset hotplug was done asynchronously via a work
function. This is to avoid recursive locking of cgroup_mutex.
Since then, the cgroup locking scheme has changed quite a bit. A
cpuset_mutex was introduced to protect cpuset specific operations.
The cpuset_mutex is then replaced by a cpuset_rwsem. With commit
d74b27d63a8b ("cgroup/cpuset: Change cpuset_rwsem and hotplug lock
order"), cpu_hotplug_lock is acquired before cpuset_rwsem. Later on,
cpuset_rwsem is reverted back to cpuset_mutex. All these locking changes
allow the hotplug code to call into cpuset core directly.
The following commits were also merged due to the asynchronous nature
of cpuset hotplug processing.
- commit b22afcdf04c9 ("cpu/hotplug: Cure the cpusets trainwreck")
- commit 50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume
bugs")
- commit 28b89b9e6f7b ("cpuset: handle race between CPU hotplug and
cpuset_hotplug_work")
Clean up all these bandages by making cpuset hotplug
processing synchronous again with the exception that the call to
cgroup_transfer_tasks() to transfer tasks out of an empty cgroup v1
cpuset, if necessary, will still be done via a work function due to the
existing cgroup_mutex -> cpu_hotplug_lock dependency. It is possible
to reverse that dependency, but that will require updating a number of
different cgroup controllers. This special hotplug code path should be
rarely taken anyway.
As all the cpuset states will be updated by the end of the hotplug
operation, we can revert most the above commits except commit
50e76632339d ("sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs")
which is partially reverted. Also removing some cpus_read_lock trylock
attempts in the cpuset partition code as they are no longer necessary
since the cpu_hotplug_lock is now held for the whole duration of the
cpuset hotplug code path.
Signed-off-by: Waiman Long <[email protected]>
Tested-by: Valentin Schneider <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
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Add a function which allows to modify easily the EM after the new voltage
information is available. The device drivers for the chip can adjust
the voltage values after setup. The voltage for the same frequency in OPP
can be different due to chip binning. The voltage impacts the power usage
and the EM power values can be updated to reflect that.
Reviewed-by: Dietmar Eggemann <[email protected]>
Signed-off-by: Lukasz Luba <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
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Extract em_table_dup() and em_recalc_and_update() from
em_adjust_new_capacity(). Both functions will be later reused by the
'update EM due to chip binning' functionality.
Reviewed-by: Dietmar Eggemann <[email protected]>
Signed-off-by: Lukasz Luba <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
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