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So that we can skip the functions in the perf lock contention and other
places like /proc/PID/wchan.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20220810220346.1919485-1-namhyung@kernel.org
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Otherwise LTO will inline them anyways and cause a large kernel text increase.
Since the explicit intention here is to not inline them marking them noinline
is good documentation even for the non-LTO case.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Martin Liska <mliska@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220719110548.1544-1-jslaby@suse.cz
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Pull irq updates from Thomas Gleixner:
"Updates for interrupt core and drivers:
Core:
- Fix a few inconsistencies between UP and SMP vs interrupt
affinities
- Small updates and cleanups all over the place
New drivers:
- LoongArch interrupt controller
- Renesas RZ/G2L interrupt controller
Updates:
- Hotpath optimization for SiFive PLIC
- Workaround for broken PLIC edge triggered interrupts
- Simall cleanups and improvements as usual"
* tag 'irq-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
irqchip/mmp: Declare init functions in common header file
irqchip/mips-gic: Check the return value of ioremap() in gic_of_init()
genirq: Use for_each_action_of_desc in actions_show()
irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch
irqchip: Add LoongArch CPU interrupt controller support
irqchip: Add Loongson Extended I/O interrupt controller support
irqchip/loongson-liointc: Add ACPI init support
irqchip/loongson-pch-msi: Add ACPI init support
irqchip/loongson-pch-pic: Add ACPI init support
irqchip: Add Loongson PCH LPC controller support
LoongArch: Prepare to support multiple pch-pic and pch-msi irqdomain
LoongArch: Use ACPI_GENERIC_GSI for gsi handling
genirq/generic_chip: Export irq_unmap_generic_chip
ACPI: irq: Allow acpi_gsi_to_irq() to have an arch-specific fallback
APCI: irq: Add support for multiple GSI domains
LoongArch: Provisionally add ACPICA data structures
irqdomain: Use hwirq_max instead of revmap_size for NOMAP domains
irqdomain: Report irq number for NOMAP domains
irqchip/gic-v3: Fix comment typo
dt-bindings: interrupt-controller: renesas,rzg2l-irqc: Document RZ/V2L SoC
...
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Pull perf events updates from Ingo Molnar:
- Fix Intel Alder Lake PEBS memory access latency & data source
profiling info bugs.
- Use Intel large-PEBS hardware feature in more circumstances, to
reduce PMI overhead & reduce sampling data.
- Extend the lost-sample profiling output with the PERF_FORMAT_LOST ABI
variant, which tells tooling the exact number of samples lost.
- Add new IBS register bits definitions.
- AMD uncore events: Add PerfMonV2 DF (Data Fabric) enhancements.
* tag 'perf-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/ibs: Add new IBS register bits into header
perf/x86/intel: Fix PEBS data source encoding for ADL
perf/x86/intel: Fix PEBS memory access info encoding for ADL
perf/core: Add a new read format to get a number of lost samples
perf/x86/amd/uncore: Add PerfMonV2 RDPMC assignments
perf/x86/amd/uncore: Add PerfMonV2 DF event format
perf/x86/amd/uncore: Detect available DF counters
perf/x86/amd/uncore: Use attr_update for format attributes
perf/x86/amd/uncore: Use dynamic events array
x86/events/intel/ds: Enable large PEBS for PERF_SAMPLE_WEIGHT_TYPE
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Pull locking updates from Ingo Molnar:
"This was a fairly quiet cycle for the locking subsystem:
- lockdep: Fix a handful of the more complex lockdep_init_map_*()
primitives that can lose the lock_type & cause false reports. No
such mishap was observed in the wild.
- jump_label improvements: simplify the cross-arch support of initial
NOP patching by making it arch-specific code (used on MIPS only),
and remove the s390 initial NOP patching that was superfluous"
* tag 'locking-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Fix lockdep_init_map_*() confusion
jump_label: make initial NOP patching the special case
jump_label: mips: move module NOP patching into arch code
jump_label: s390: avoid pointless initial NOP patching
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Pull scheduler updates from Ingo Molnar:
"Load-balancing improvements:
- Improve NUMA balancing on AMD Zen systems for affine workloads.
- Improve the handling of reduced-capacity CPUs in load-balancing.
- Energy Model improvements: fix & refine all the energy fairness
metrics (PELT), and remove the conservative threshold requiring 6%
energy savings to migrate a task. Doing this improves power
efficiency for most workloads, and also increases the reliability
of energy-efficiency scheduling.
- Optimize/tweak select_idle_cpu() to spend (much) less time
searching for an idle CPU on overloaded systems. There's reports of
several milliseconds spent there on large systems with large
workloads ...
[ Since the search logic changed, there might be behavioral side
effects. ]
- Improve NUMA imbalance behavior. On certain systems with spare
capacity, initial placement of tasks is non-deterministic, and such
an artificial placement imbalance can persist for a long time,
hurting (and sometimes helping) performance.
The fix is to make fork-time task placement consistent with runtime
NUMA balancing placement.
Note that some performance regressions were reported against this,
caused by workloads that are not memory bandwith limited, which
benefit from the artificial locality of the placement bug(s). Mel
Gorman's conclusion, with which we concur, was that consistency is
better than random workload benefits from non-deterministic bugs:
"Given there is no crystal ball and it's a tradeoff, I think
it's better to be consistent and use similar logic at both fork
time and runtime even if it doesn't have universal benefit."
- Improve core scheduling by fixing a bug in
sched_core_update_cookie() that caused unnecessary forced idling.
- Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs
for newly woken tasks.
- Fix a newidle balancing bug that introduced unnecessary wakeup
latencies.
ABI improvements/fixes:
- Do not check capabilities and do not issue capability check denial
messages when a scheduler syscall doesn't require privileges. (Such
as increasing niceness.)
- Add forced-idle accounting to cgroups too.
- Fix/improve the RSEQ ABI to not just silently accept unknown flags.
(No existing tooling is known to have learned to rely on the
previous behavior.)
- Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags.
Optimizations:
- Optimize & simplify leaf_cfs_rq_list()
- Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg().
Misc fixes & cleanups:
- Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems.
- Fix a full-NOHZ bug that can in some cases result in the tick not
being re-enabled when the last SCHED_RT task is gone from a
runqueue but there's still SCHED_OTHER tasks around.
- Various PREEMPT_RT related fixes.
- Misc cleanups & smaller fixes"
* tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
rseq: Kill process when unknown flags are encountered in ABI structures
rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags
sched/core: Fix the bug that task won't enqueue into core tree when update cookie
nohz/full, sched/rt: Fix missed tick-reenabling bug in dequeue_task_rt()
sched/core: Always flush pending blk_plug
sched/fair: fix case with reduced capacity CPU
sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling
sched/core: add forced idle accounting for cgroups
sched/fair: Remove the energy margin in feec()
sched/fair: Remove task_util from effective utilization in feec()
sched/fair: Use the same cpumask per-PD throughout find_energy_efficient_cpu()
sched/fair: Rename select_idle_mask to select_rq_mask
sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()
sched/fair: Decay task PELT values during wakeup migration
sched/fair: Provide u64 read for 32-bits arch helper
sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
sched: only perform capability check on privileged operation
sched: Remove unused function group_first_cpu()
sched/fair: Remove redundant word " *"
selftests/rseq: check if libc rseq support is registered
...
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rseq_abi()->flags and rseq_abi()->rseq_cs->flags 29 upper bits are
currently unused.
The current behavior when those bits are set is to ignore them. This is
not an ideal behavior, because when future features will start using
those flags, if user-space fails to correctly validate that the kernel
indeed supports those flags (e.g. with a new sys_rseq flags bit) before
using them, it may incorrectly assume that the kernel will handle those
flags way when in fact those will be silently ignored on older kernels.
Validating that unused flags bits are cleared will allow a smoother
transition when those flags will start to be used by allowing
applications to fail early, and obviously, when they attempt to use the
new flags on an older kernel that does not support them.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20220622194617.1155957-2-mathieu.desnoyers@efficios.com
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The pretty much unused RSEQ_CS_FLAG_NO_RESTART_ON_* flags introduce
complexity in rseq, and are subtly buggy [1]. Solving those issues
requires introducing additional complexity in the rseq implementation
for each supported architecture.
Considering that it complexifies the rseq ABI, I am proposing that we
deprecate those flags. [2]
So far there appears to be consensus from maintainers of user-space
projects impacted by this feature that its removal would be a welcome
simplification. [3]
The deprecation approach proposed here is to issue WARN_ON_ONCE() when
encountering those flags and kill the offending process with sigsegv.
This should allow us to quickly identify whether anyone yells at us for
removing this.
Link: https://lore.kernel.org/lkml/20220618182515.95831-1-minhquangbui99@gmail.com/ [1]
Link: https://lore.kernel.org/lkml/258546133.12151.1655739550814.JavaMail.zimbra@efficios.com/ [2]
Link: https://lore.kernel.org/lkml/87pmj1enjh.fsf@email.froward.int.ebiederm.org/ [3]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/lkml/20220622194617.1155957-1-mathieu.desnoyers@efficios.com
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Pull x86 fixes from Borislav Petkov:
- Update the 'mitigations=' kernel param documentation
- Check the IBPB feature flag before enabling IBPB in firmware calls
because cloud vendors' fantasy when it comes to creating guest
configurations is unlimited
- Unexport sev_es_ghcb_hv_call() before 5.19 releases now that HyperV
doesn't need it anymore
- Remove dead CONFIG_* items
* tag 'x86_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
docs/kernel-parameters: Update descriptions for "mitigations=" param with retbleed
x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available
Revert "x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV"
x86/configs: Update configs in x86_debug.config
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Pull locking fix from Borislav Petkov:
- Avoid rwsem lockups in certain situations when handling the handoff
bit
* tag 'locking_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by first waiter
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With commit d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more
consistent"), the writer that sets the handoff bit can be interrupted
out without clearing the bit if the wait queue isn't empty. This disables
reader and writer optimistic lock spinning and stealing.
Now if a non-first writer in the queue is somehow woken up or a new
waiter enters the slowpath, it can't acquire the lock. This is not the
case before commit d257cc8cb8d5 as the writer that set the handoff bit
will clear it when exiting out via the out_nolock path. This is less
efficient as the busy rwsem stays in an unlock state for a longer time.
In some cases, this new behavior may cause lockups as shown in [1] and
[2].
This patch allows a non-first writer to ignore the handoff bit if it
is not originally set or initiated by the first waiter. This patch is
shown to be effective in fixing the lockup problem reported in [1].
[1] https://lore.kernel.org/lkml/20220617134325.GC30825@techsingularity.net/
[2] https://lore.kernel.org/lkml/3f02975c-1a9d-be20-32cf-f1d8e3dfafcc@oracle.com/
Fixes: d257cc8cb8d5 ("locking/rwsem: Make handoff bit handling more consistent")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20220622200419.778799-1-longman@redhat.com
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Pull workqueue fix from Tejun Heo:
"Just one commit to suppress a spurious warning added during the 5.19
cycle"
* tag 'wq-for-5.19-rc8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Avoid a false warning in unbind_workers()
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Doing set_cpus_allowed_ptr() with wq_unbound_cpumask can be possible
fails and trigger the false warning.
Use cpu_possible_mask instead when wq_unbound_cpumask has no active CPUs.
It is very easy to trigger the warning:
Set wq_unbound_cpumask to a small set of CPUs.
Offline all the CPUs of wq_unbound_cpumask.
Offline an extra CPU and trigger the warning.
Fixes: 10a5a651e3af ("workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs")
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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If a watch is being added to a queue, it needs to guard against
interference from addition of a new watch, manual removal of a watch and
removal of a watch due to some other queue being destroyed.
KEYCTL_WATCH_KEY guards against this for the same {key,queue} pair by
holding the key->sem writelocked and by holding refs on both the key and
the queue - but that doesn't prevent interaction from other {key,queue}
pairs.
While add_watch_to_object() does take the spinlock on the event queue,
it doesn't take the lock on the source's watch list. The assumption was
that the caller would prevent that (say by taking key->sem) - but that
doesn't prevent interference from the destruction of another queue.
Fix this by locking the watcher list in add_watch_to_object().
Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Reported-by: syzbot+03d7b43290037d1f87ca@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: keyrings@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since __post_watch_notification() walks wlist->watchers with only the
RCU read lock held, we need to use RCU methods to add to the list (we
already use RCU methods to remove from the list).
Fix add_watch_to_object() to use hlist_add_head_rcu() instead of
hlist_add_head() for that list.
Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull irqchip/genirq updates from Marc Zyngier:
* Core code update:
- Non-SMP IRQ affinity fixes, allowing UP kernel to behave similarly
to SMP ones for the purpose of interrupt affinity
- Let irq_set_chip_handler_name_locked() take a const struct irq_chip *
- Tidy-up the NOMAP irqdomain API variant
- Teach action_show() to use for_each_action_of_desc()
- Make irq_chip_request_resources_parent() allow the parent callback
to be optional
- Remove dynamic allocations from populate_parent_alloc_arg()
* New drivers:
- Merge the long awaited IRQ support for the LoongArch architecture,
with the provisional ACPICA update (to be reverted once the official
support lands)
- New Renesas RZ/G2L IRQC driver, equipped with its companion GPIO
driver
* Driver updates
- Optimise the hot path operations for the SiFive PLIC, trading the
locking for per-CPU priority masking masking operations which are
apparently faster
- Work around broken PLIC implementations that deal pretty badly with
edge-triggered interrupts. Flag two implementations as affected.
- Simplify the irq-stm32-exti driver, particularly the table that
remaps the interrupts from exti to the GIC, reducing the memory usage
- Convert the ocelot irq_chip to being immutable
- Check ioremap() return value in the MIPS GIC driver
- Move MMP driver init function declarations into the common .h
- The obligatory typo fixes
Link: https://lore.kernel.org/all/20220727192356.1860546-1-maz@kernel.org
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Commit
4675ff05de2d ("kmemcheck: rip it out")
removed kmemcheck and its corresponding build config KMEMCHECK.
Commit
0f620cefd775 ("objtool: Rename "VMLINUX_VALIDATION" -> "NOINSTR_VALIDATION"")
renamed the debug config option.
Adjust x86_debug.config to those changes in debug configs.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220722121815.27535-1-lukas.bulwahn@gmail.com
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* irq/misc-5.20:
: .
: Misc IRQ changes for 5.20:
:
: - Let irq_set_chip_handler_name_locked() take a const struct irq_chip *
:
: - Convert the ocelot irq_chip to being immutable (depends on the above)
:
: - Tidy-up the NOMAP irqdomain API variant
:
: - Teach action_show() to use for_each_action_of_desc()
:
: - Check ioremap() return value in the MIPS GIC driver
:
: - Move MMP driver init function declarations into the common .h
:
: - The obligatory typo fixes
: .
irqchip/mmp: Declare init functions in common header file
irqchip/mips-gic: Check the return value of ioremap() in gic_of_init()
genirq: Use for_each_action_of_desc in actions_show()
irqdomain: Use hwirq_max instead of revmap_size for NOMAP domains
irqdomain: Report irq number for NOMAP domains
irqchip/gic-v3: Fix comment typo
pinctrl: ocelot: Make irq_chip immutable
genirq: Allow irq_set_chip_handler_name_locked() to take a const irq_chip
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Pull scheduler fix from Borislav Petkov:
"A single fix to correct a wrong BUG_ON() condition for deboosted
tasks"
* tag 'sched_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Fix BUG_ON condition for deboosted tasks
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Pull RCU fix from Paul McKenney:
"This contains a pair of commits that fix 282d8998e997 ("srcu: Prevent
expedited GPs and blocking readers from consuming CPU"), which was
itself a fix to an SRCU expedited grace-period problem that could
prevent kernel live patching (KLP) from completing.
That SRCU fix for KLP introduced large (as in minutes) boot-time
delays to embedded Linux kernels running on qemu/KVM. These delays
were due to the emulation of certain MMIO operations controlling
memory layout, which were emulated with one expedited grace period per
access. Common configurations required thousands of boot-time MMIO
accesses, and thus thousands of boot-time expedited SRCU grace
periods.
In these configurations, the occasional sleeps that allowed KLP to
proceed caused excessive boot delays. These commits preserve enough
sleeps to permit KLP to proceed, but few enough that the virtual
embedded kernels still boot reasonably quickly.
This represents a regression introduced in the v5.19 merge window, and
the bug is causing significant inconvenience"
* tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
srcu: Make expedited RCU grace periods block even less frequently
srcu: Block less aggressively for expedited grace periods
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Sedat Dilek noticed that I had an extraneous semicolon at the end of a
line in the previous patch.
It's harmless, but unintentional, and while compilers just treat it as
an extra empty statement, for all I know some other tooling might warn
about it. So clean it up before other people notice too ;)
Fixes: 353f7988dd84 ("watchqueue: make sure to serialize 'wqueue->defunct' properly")
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
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In function sched_core_update_cookie(), a task will enqueue into the
core tree only when it enqueued before, that is, if an uncookied task
is cookied, it will not enqueue into the core tree until it enqueue
again, which will result in unnecessary force idle.
Here follows the scenario:
CPU x and CPU y are a pair of SMT siblings.
1. Start task a running on CPU x without sleeping, and task b and
task c running on CPU y without sleeping.
2. We create a cookie and share it to task a and task b, and then
we create another cookie and share it to task c.
3. Simpling core_forceidle_sum of task a and b from /proc/PID/sched
And we will find out that core_forceidle_sum of task a takes 30%
time of the sampling period, which shouldn't happen as task a and b
have the same cookie.
Then we migrate task a to CPU x', migrate task b and c to CPU y', where
CPU x' and CPU y' are a pair of SMT siblings, and sampling again, we
will found out that core_forceidle_sum of task a and b are almost zero.
To solve this problem, we enqueue the task into the core tree if it's
on rq.
Fixes: 6e33cad0af49("sched: Trivial core scheduling cookie management")
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1656403045-100840-2-git-send-email-CruzZhao@linux.alibaba.com
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dequeue_task_rt() only decrements 'rt_rq->rt_nr_running' after having
called sched_update_tick_dependency() preventing it from re-enabling the
tick on systems that no longer have pending SCHED_RT tasks but have
multiple runnable SCHED_OTHER tasks:
dequeue_task_rt()
dequeue_rt_entity()
dequeue_rt_stack()
dequeue_top_rt_rq()
sub_nr_running() // decrements rq->nr_running
sched_update_tick_dependency()
sched_can_stop_tick() // checks rq->rt.rt_nr_running,
...
__dequeue_rt_entity()
dec_rt_tasks() // decrements rq->rt.rt_nr_running
...
Every other scheduler class performs the operation in the opposite
order, and sched_update_tick_dependency() expects the values to be
updated as such. So avoid the misbehaviour by inverting the order in
which the above operations are performed in the RT scheduler.
Fixes: 76d92ac305f2 ("sched: Migrate sched to use new tick dependency mask model")
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lore.kernel.org/r/20220628092259.330171-1-nsaenzju@redhat.com
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Tasks the are being deboosted from SCHED_DEADLINE might enter
enqueue_task_dl() one last time and hit an erroneous BUG_ON condition:
since they are not boosted anymore, the if (is_dl_boosted()) branch is
not taken, but the else if (!dl_prio) is and inside this one we
BUG_ON(!is_dl_boosted), which is of course false (BUG_ON triggered)
otherwise we had entered the if branch above. Long story short, the
current condition doesn't make sense and always leads to triggering of a
BUG.
Fix this by only checking enqueue flags, properly: ENQUEUE_REPLENISH has
to be present, but additional flags are not a problem.
Fixes: 64be6f1f5f71 ("sched/deadline: Don't replenish from a !SCHED_DEADLINE entity")
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220714151908.533052-1-juri.lelli@redhat.com
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When the pipe is closed, we mark the associated watchqueue defunct by
calling watch_queue_clear(). However, while that is protected by the
watchqueue lock, new watchqueue entries aren't actually added under that
lock at all: they use the pipe->rd_wait.lock instead, and looking up
that pipe happens without any locking.
The watchqueue code uses the RCU read-side section to make sure that the
wqueue entry itself hasn't disappeared, but that does not protect the
pipe_info in any way.
So make sure to actually hold the wqueue lock when posting watch events,
properly serializing against the pipe being torn down.
Reported-by: Noam Rathaus <noamr@ssd-disclosure.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* irq/loongarch:
: .
: Merge the long awaited IRQ support for the LoongArch architecture.
:
: From the cover letter:
:
: "Currently, LoongArch based processors (e.g. Loongson-3A5000)
: can only work together with LS7A chipsets. The irq chips in
: LoongArch computers include CPUINTC (CPU Core Interrupt
: Controller), LIOINTC (Legacy I/O Interrupt Controller),
: EIOINTC (Extended I/O Interrupt Controller), PCH-PIC (Main
: Interrupt Controller in LS7A chipset), PCH-LPC (LPC Interrupt
: Controller in LS7A chipset) and PCH-MSI (MSI Interrupt Controller)."
:
: Note that this comes with non-official, arch private ACPICA
: definitions until the official ACPICA update is realeased.
: .
irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch
irqchip: Add LoongArch CPU interrupt controller support
irqchip: Add Loongson Extended I/O interrupt controller support
irqchip/loongson-liointc: Add ACPI init support
irqchip/loongson-pch-msi: Add ACPI init support
irqchip/loongson-pch-pic: Add ACPI init support
irqchip: Add Loongson PCH LPC controller support
LoongArch: Prepare to support multiple pch-pic and pch-msi irqdomain
LoongArch: Use ACPI_GENERIC_GSI for gsi handling
genirq/generic_chip: Export irq_unmap_generic_chip
ACPI: irq: Allow acpi_gsi_to_irq() to have an arch-specific fallback
APCI: irq: Add support for multiple GSI domains
LoongArch: Provisionally add ACPICA data structures
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Refactor action_show() to use for_each_action_of_desc instead
of a similar open-coded loop.
Signed-off-by: Paran Lee <p4ranlee@gmail.com>
[maz: reword commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220710112614.19410-1-p4ranlee@gmail.com
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Some irq controllers have to re-implement a private version for
irq_generic_chip_ops, because they have a different xlate to translate
hwirq. Export irq_unmap_generic_chip to allow reusing in drivers.
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1658314292-35346-5-git-send-email-lvjianmin@loongson.cn
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The purpose of commit 282d8998e997 ("srcu: Prevent expedited GPs
and blocking readers from consuming CPU") was to prevent a long
series of never-blocking expedited SRCU grace periods from blocking
kernel-live-patching (KLP) progress. Although it was successful, it also
resulted in excessive boot times on certain embedded workloads running
under qemu with the "-bios QEMU_EFI.fd" command line. Here "excessive"
means increasing the boot time up into the three-to-four minute range.
This increase in boot time was due to the more than 6000 back-to-back
invocations of synchronize_rcu_expedited() within the KVM host OS, which
in turn resulted from qemu's emulation of a long series of MMIO accesses.
Commit 640a7d37c3f4 ("srcu: Block less aggressively for expedited grace
periods") did not significantly help this particular use case.
Zhangfei Gao and Shameerali Kolothum Thodi did experiments varying the
value of SRCU_MAX_NODELAY_PHASE with HZ=250 and with various values
of non-sleeping per phase counts on a system with preemption enabled,
and observed the following boot times:
+──────────────────────────+────────────────+
| SRCU_MAX_NODELAY_PHASE | Boot time (s) |
+──────────────────────────+────────────────+
| 100 | 30.053 |
| 150 | 25.151 |
| 200 | 20.704 |
| 250 | 15.748 |
| 500 | 11.401 |
| 1000 | 11.443 |
| 10000 | 11.258 |
| 1000000 | 11.154 |
+──────────────────────────+────────────────+
Analysis on the experiment results show additional improvements with
CPU-bound delays approaching one jiffy in duration. This improvement was
also seen when number of per-phase iterations were scaled to one jiffy.
This commit therefore scales per-grace-period phase number of non-sleeping
polls so that non-sleeping polls extend for about one jiffy. In addition,
the delay-calculation call to srcu_get_delay() in srcu_gp_end() is
replaced with a simple check for an expedited grace period. This change
schedules callback invocation immediately after expedited grace periods
complete, which results in greatly improved boot times. Testing done
by Marc and Zhangfei confirms that this change recovers most of the
performance degradation in boottime; for CONFIG_HZ_250 configuration,
specifically, boot times improve from 3m50s to 41s on Marc's setup;
and from 2m40s to ~9.7s on Zhangfei's setup.
In addition to the changes to default per phase delays, this
change adds 3 new kernel parameters - srcutree.srcu_max_nodelay,
srcutree.srcu_max_nodelay_phase, and srcutree.srcu_retry_check_delay.
This allows users to configure the srcu grace period scanning delays in
order to more quickly react to additional use cases.
Fixes: 640a7d37c3f4 ("srcu: Block less aggressively for expedited grace periods")
Fixes: 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers from consuming CPU")
Reported-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reported-by: yueluck <yueluck@163.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Link: https://lore.kernel.org/all/20615615-0013-5adc-584f-2b1d5c03ebfc@linaro.org/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Commit 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers
from consuming CPU") fixed a problem where a long-running expedited SRCU
grace period could block kernel live patching. It did so by giving up
on expediting once a given SRCU expedited grace period grew too old.
Unfortunately, this added excessive delays to boots of virtual embedded
systems specifying "-bios QEMU_EFI.fd" to qemu. This commit therefore
makes the transition away from expediting less aggressive, increasing
the per-grace-period phase number of non-sleeping polls of readers from
one to three and increasing the required grace-period age from one jiffy
(actually from zero to one jiffies) to two jiffies (actually from one
to two jiffies).
Fixes: 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers from consuming CPU")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reported-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reported-by: chenxiang (M)" <chenxiang66@hisilicon.com>
Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Link: https://lore.kernel.org/all/20615615-0013-5adc-584f-2b1d5c03ebfc@linaro.org/
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NOMAP irq domains use the revmap_size field to indicate the maximum
hwirq number the domain accepts. This is a bit confusing as
revmap_size is usually used to indicate the size of the revmap array,
which a NOMAP domain doesn't have.
Instead, use the hwirq_max field which has the correct semantics, and
keep revmap_size to 0 for a NOMAP domain.
Signed-off-by: Xu Qiang <xuqiang36@huawei.com>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220719063641.56541-3-xuqiang36@huawei.com
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When using a NOMAP domain, __irq_resolve_mapping() doesn't store
the Linux IRQ number at the address optionally provided by the caller.
While this isn't a huge deal (the returned value is guaranteed
to the hwirq that was passed as a parameter), let's honour the letter
of the API by writing the expected value.
Fixes: d22558dd0a6c (“irqdomain: Introduce irq_resolve_mapping()”)
Signed-off-by: Xu Qiang <xuqiang36@huawei.com>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220719063641.56541-2-xuqiang36@huawei.com
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Pull perf fix from Borislav Petkov:
- A single data race fix on the perf event cleanup path to avoid
endless loops due to insufficient locking
* tag 'perf_urgent_for_v5.19_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix data race between perf_event_set_output() and perf_mmap_close()
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Pull printk fix from Petr Mladek:
- Make pr_flush() fast when consoles are suspended.
* tag 'printk-for-5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk: do not wait for consoles when suspended
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Pyll sysctl fix from Luis Chamberlain:
"Only one fix for sysctl"
* tag 'sysctl-fixes-5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
mm: sysctl: fix missing numa_stat when !CONFIG_HUGETLB_PAGE
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The console_stop() and console_start() functions call pr_flush().
When suspending, these functions are called by the serial subsystem
while the serial port is suspended. In this scenario, if there are
any pending messages, a call to pr_flush() will always result in a
timeout because the serial port cannot make forward progress. This
causes longer suspend and resume times.
Add a check in pr_flush() so that it will immediately timeout if
the consoles are suspended.
Fixes: 3b604ca81202 ("printk: add pr_flush()")
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220715061042.373640-2-john.ogness@linutronix.de
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"numa_stat" should not be included in the scope of CONFIG_HUGETLB_PAGE, if
CONFIG_HUGETLB_PAGE is not configured even if CONFIG_NUMA is configured,
"numa_stat" is missed form /proc. Move it out of CONFIG_HUGETLB_PAGE to
fix it.
Fixes: 4518085e127d ("mm, sysctl: make NUMA stats configurable")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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Pull networking fixes from Jakub Kicinski:
"Including fixes from netfilter, bpf and wireless.
Still no major regressions, the release continues to be calm. An
uptick of fixes this time around due to trivial data race fixes and
patches flowing down from subtrees.
There has been a few driver fixes (particularly a few fixes for false
positives due to 66e4c8d95008 which went into -next in May!) that make
me worry the wide testing is not exactly fully through.
So "calm" but not "let's just cut the final ASAP" vibes over here.
Current release - regressions:
- wifi: rtw88: fix write to const table of channel parameters
Current release - new code bugs:
- mac80211: add gfp_t arg to ieeee80211_obss_color_collision_notify
- mlx5:
- TC, allow offload from uplink to other PF's VF
- Lag, decouple FDB selection and shared FDB
- Lag, correct get the port select mode str
- bnxt_en: fix and simplify XDP transmit path
- r8152: fix accessing unset transport header
Previous releases - regressions:
- conntrack: fix crash due to confirmed bit load reordering (after
atomic -> refcount conversion)
- stmmac: dwc-qos: disable split header for Tegra194
Previous releases - always broken:
- mlx5e: ring the TX doorbell on DMA errors
- bpf: make sure mac_header was set before using it
- mac80211: do not wake queues on a vif that is being stopped
- mac80211: fix queue selection for mesh/OCB interfaces
- ip: fix dflt addr selection for connected nexthop
- seg6: fix skb checksums for SRH encapsulation/insertion
- xdp: fix spurious packet loss in generic XDP TX path
- bunch of sysctl data race fixes
- nf_log: incorrect offset to network header
Misc:
- bpf: add flags arg to bpf_dynptr_read and bpf_dynptr_write APIs"
* tag 'net-5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (87 commits)
nfp: flower: configure tunnel neighbour on cmsg rx
net/tls: Check for errors in tls_device_init
MAINTAINERS: Add an additional maintainer to the AMD XGBE driver
xen/netback: avoid entering xenvif_rx_next_skb() with an empty rx queue
selftests/net: test nexthop without gw
ip: fix dflt addr selection for connected nexthop
net: atlantic: remove aq_nic_deinit() when resume
net: atlantic: remove deep parameter on suspend/resume functions
sfc: fix kernel panic when creating VF
seg6: bpf: fix skb checksum in bpf_push_seg6_encap()
seg6: fix skb checksum in SRv6 End.B6 and End.B6.Encaps behaviors
seg6: fix skb checksum evaluation in SRH encapsulation/insertion
sfc: fix use after free when disabling sriov
net: sunhme: output link status with a single print.
r8152: fix accessing unset transport header
net: stmmac: fix leaks in probe
net: ftgmac100: Hold reference returned by of_get_child_by_name()
nexthop: Fix data-races around nexthop_compat_mode.
ipv4: Fix data-races around sysctl_ip_dynaddr.
tcp: Fix a data-race around sysctl_tcp_ecn_fallback.
...
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Pull integrity fixes from Mimi Zohar:
"Here are a number of fixes for recently found bugs.
Only 'ima: fix violation measurement list record' was introduced in
the current release. The rest address existing bugs"
* tag 'integrity-v5.19-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
ima: Fix potential memory leak in ima_init_crypto()
ima: force signature verification when CONFIG_KEXEC_SIG is configured
ima: Fix a potential integer overflow in ima_appraise_measurement
ima: fix violation measurement list record
Revert "evm: Fix memleak in init_desc"
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Pull cgroup fix from Tejun Heo:
"Fix an old and subtle bug in the migration path.
css_sets are used to track tasks and migrations are tasks moving from
a group of css_sets to another group of css_sets. The migration path
pins all source and destination css_sets in the prep stage.
Unfortunately, it was overloading the same list_head entry to track
sources and destinations, which got confused for migrations which are
partially identity leading to use-after-frees.
Fixed by using dedicated list_heads for tracking sources and
destinations"
* tag 'cgroup-for-5.19-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Use separate src/dst nodes when preloading css_sets for migration
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Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce kernel
signature verification check in the kexec_file_load syscall when IMA
arch specific policy is configured.
Fixes: 99d5cadfde2b ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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A sysctl variable is accessed concurrently, and there is always a chance
of data-race. So, all readers and writers need some basic protection to
avoid load/store-tearing.
This patch changes proc_dointvec_ms_jiffies() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side. For now,
proc_dointvec_ms_jiffies() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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A sysctl variable is accessed concurrently, and there is always a chance
of data-race. So, all readers and writers need some basic protection to
avoid load/store-tearing.
This patch changes proc_dou8vec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side. For now,
proc_dou8vec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.
Fixes: cb9444130662 ("sysctl: add proc_dou8vec_minmax()")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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With CONFIG_PREEMPT_RT, it is possible to hit a deadlock between two
normal priority tasks (SCHED_OTHER, nice level zero):
INFO: task kworker/u8:0:8 blocked for more than 491 seconds.
Not tainted 5.15.49-rt46 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0 state:D stack: 0 pid: 8 ppid: 2 flags:0x00000000
Workqueue: writeback wb_workfn (flush-7:0)
[<c08a3a10>] (__schedule) from [<c08a3d84>] (schedule+0xdc/0x134)
[<c08a3d84>] (schedule) from [<c08a65a0>] (rt_mutex_slowlock_block.constprop.0+0xb8/0x174)
[<c08a65a0>] (rt_mutex_slowlock_block.constprop.0) from [<c08a6708>]
+(rt_mutex_slowlock.constprop.0+0xac/0x174)
[<c08a6708>] (rt_mutex_slowlock.constprop.0) from [<c0374d60>] (fat_write_inode+0x34/0x54)
[<c0374d60>] (fat_write_inode) from [<c0297304>] (__writeback_single_inode+0x354/0x3ec)
[<c0297304>] (__writeback_single_inode) from [<c0297998>] (writeback_sb_inodes+0x250/0x45c)
[<c0297998>] (writeback_sb_inodes) from [<c0297c20>] (__writeback_inodes_wb+0x7c/0xb8)
[<c0297c20>] (__writeback_inodes_wb) from [<c0297f24>] (wb_writeback+0x2c8/0x2e4)
[<c0297f24>] (wb_writeback) from [<c0298c40>] (wb_workfn+0x1a4/0x3e4)
[<c0298c40>] (wb_workfn) from [<c0138ab8>] (process_one_work+0x1fc/0x32c)
[<c0138ab8>] (process_one_work) from [<c0139120>] (worker_thread+0x22c/0x2d8)
[<c0139120>] (worker_thread) from [<c013e6e0>] (kthread+0x16c/0x178)
[<c013e6e0>] (kthread) from [<c01000fc>] (ret_from_fork+0x14/0x38)
Exception stack(0xc10e3fb0 to 0xc10e3ff8)
3fa0: 00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
INFO: task tar:2083 blocked for more than 491 seconds.
Not tainted 5.15.49-rt46 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:tar state:D stack: 0 pid: 2083 ppid: 2082 flags:0x00000000
[<c08a3a10>] (__schedule) from [<c08a3d84>] (schedule+0xdc/0x134)
[<c08a3d84>] (schedule) from [<c08a41b0>] (io_schedule+0x14/0x24)
[<c08a41b0>] (io_schedule) from [<c08a455c>] (bit_wait_io+0xc/0x30)
[<c08a455c>] (bit_wait_io) from [<c08a441c>] (__wait_on_bit_lock+0x54/0xa8)
[<c08a441c>] (__wait_on_bit_lock) from [<c08a44f4>] (out_of_line_wait_on_bit_lock+0x84/0xb0)
[<c08a44f4>] (out_of_line_wait_on_bit_lock) from [<c0371fb0>] (fat_mirror_bhs+0xa0/0x144)
[<c0371fb0>] (fat_mirror_bhs) from [<c0372a68>] (fat_alloc_clusters+0x138/0x2a4)
[<c0372a68>] (fat_alloc_clusters) from [<c0370b14>] (fat_alloc_new_dir+0x34/0x250)
[<c0370b14>] (fat_alloc_new_dir) from [<c03787c0>] (vfat_mkdir+0x58/0x148)
[<c03787c0>] (vfat_mkdir) from [<c0277b60>] (vfs_mkdir+0x68/0x98)
[<c0277b60>] (vfs_mkdir) from [<c027b484>] (do_mkdirat+0xb0/0xec)
[<c027b484>] (do_mkdirat) from [<c0100060>] (ret_fast_syscall+0x0/0x1c)
Exception stack(0xc2e1bfa8 to 0xc2e1bff0)
bfa0: 01ee42f0 01ee4208 01ee42f0 000041ed 00000000 00004000
bfc0: 01ee42f0 01ee4208 00000000 00000027 01ee4302 00000004 000dcb00 01ee4190
bfe0: 000dc368 bed11924 0006d4b0 b6ebddfc
Here the kworker is waiting on msdos_sb_info::s_lock which is held by
tar which is in turn waiting for a buffer which is locked waiting to be
flushed, but this operation is plugged in the kworker.
The lock is a normal struct mutex, so tsk_is_pi_blocked() will always
return false on !RT and thus the behaviour changes for RT.
It seems that the intent here is to skip blk_flush_plug() in the case
where a non-preemptible lock (such as a spinlock) has been converted to
a rtmutex on RT, which is the case covered by the SM_RTLOCK_WAIT
schedule flag. But sched_submit_work() is only called from schedule()
which is never called in this scenario, so the check can simply be
deleted.
Looking at the history of the -rt patchset, in fact this change was
present from v5.9.1-rt20 until being dropped in v5.13-rt1 as it was part
of a larger patch [1] most of which was replaced by commit b4bfa3fcfe3b
("sched/core: Rework the __schedule() preempt argument").
As described in [1]:
The schedule process must distinguish between blocking on a regular
sleeping lock (rwsem and mutex) and a RT-only sleeping lock (spinlock
and rwlock):
- rwsem and mutex must flush block requests (blk_schedule_flush_plug())
even if blocked on a lock. This can not deadlock because this also
happens for non-RT.
There should be a warning if the scheduling point is within a RCU read
section.
- spinlock and rwlock must not flush block requests. This will deadlock
if the callback attempts to acquire a lock which is already acquired.
Similarly to being preempted, there should be no warning if the
scheduling point is within a RCU read section.
and with the tsk_is_pi_blocked() in the scheduler path, we hit the first
issue.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches/0022-locking-rtmutex-Use-custom-scheduling-function-for-s.patch?h=linux-5.10.y-rt-patches
Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lkml.kernel.org/r/20220708162702.1758865-1-john@metanate.com
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The capacity of the CPU available for CFS tasks can be reduced because of
other activities running on the latter. In such case, it's worth trying to
move CFS tasks on a CPU with more available capacity.
The rework of the load balance has filtered the case when the CPU is
classified to be fully busy but its capacity is reduced.
Check if CPU's capacity is reduced while gathering load balance statistic
and classify it group_misfit_task instead of group_fully_busy so we can
try to move the load on another CPU.
Reported-by: David Chen <david.chen@nutanix.com>
Reported-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: David Chen <david.chen@nutanix.com>
Tested-by: Zhang Qiao <zhangqiao22@huawei.com>
Link: https://lkml.kernel.org/r/20220708154401.21411-1-vincent.guittot@linaro.org
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Yang Jihing reported a race between perf_event_set_output() and
perf_mmap_close():
CPU1 CPU2
perf_mmap_close(e2)
if (atomic_dec_and_test(&e2->rb->mmap_count)) // 1 - > 0
detach_rest = true
ioctl(e1, IOC_SET_OUTPUT, e2)
perf_event_set_output(e1, e2)
...
list_for_each_entry_rcu(e, &e2->rb->event_list, rb_entry)
ring_buffer_attach(e, NULL);
// e1 isn't yet added and
// therefore not detached
ring_buffer_attach(e1, e2->rb)
list_add_rcu(&e1->rb_entry,
&e2->rb->event_list)
After this; e1 is attached to an unmapped rb and a subsequent
perf_mmap() will loop forever more:
again:
mutex_lock(&e->mmap_mutex);
if (event->rb) {
...
if (!atomic_inc_not_zero(&e->rb->mmap_count)) {
...
mutex_unlock(&e->mmap_mutex);
goto again;
}
}
The loop in perf_mmap_close() holds e2->mmap_mutex, while the attach
in perf_event_set_output() holds e1->mmap_mutex. As such there is no
serialization to avoid this race.
Change perf_event_set_output() to take both e1->mmap_mutex and
e2->mmap_mutex to alleviate that problem. Additionally, have the loop
in perf_mmap() detach the rb directly, this avoids having to wait for
the concurrent perf_mmap_close() to get around to doing it to make
progress.
Fixes: 9bb5d40cd93c ("perf: Fix mmap() accounting hole")
Reported-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yang Jihong <yangjihong1@huawei.com>
Link: https://lkml.kernel.org/r/YsQ3jm2GR38SW7uD@worktop.programming.kicks-ass.net
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Pull tracing fixes from Steven Rostedt:
"Fixes and minor clean ups for tracing:
- Fix memory leak by reverting what was thought to be a double free.
A static tool had gave a false positive that a double free was
possible in the error path, but it was actually a different
location that confused the static analyzer (and those of us that
reviewed it).
- Move use of static buffers by ftrace_dump() to a location that can
be used by kgdb's ftdump(), as it needs it for the same reasons.
- Clarify in the Kconfig description that function tracing has
negligible impact on x86, but may have a bit bigger impact on other
architectures.
- Remove unnecessary extra semicolon in trace event.
- Make a local variable static that is used in the fprobes sample
- Use KSYM_NAME_LEN for length of function in kprobe sample and get
rid of unneeded macro for the same purpose"
* tag 'trace-v5.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
samples: Use KSYM_NAME_LEN for kprobes
fprobe/samples: Make sample_probe static
blk-iocost: tracing: atomic64_read(&ioc->vtime_rate) is assigned an extra semicolon
ftrace: Be more specific about arch impact when function tracer is enabled
tracing: Fix sleeping while atomic in kdb ftdump
tracing/histograms: Fix memory leak problem
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It was brought up that on ARMv7, that because the FUNCTION_TRACER does not
use nops to keep function tracing disabled because of the use of a link
register, it does have some performance impact.
The start of functions when -pg is used to compile the kernel is:
push {lr}
bl 8010e7c0 <__gnu_mcount_nc>
When function tracing is tuned off, it becomes:
push {lr}
add sp, sp, #4
Which just puts the stack back to its normal location. But these two
instructions at the start of every function does incur some overhead.
Be more honest in the Kconfig FUNCTION_TRACER description and specify that
the overhead being in the noise was x86 specific, but other architectures
may vary.
Link: https://lore.kernel.org/all/20220705105416.GE5208@pengutronix.de/
Link: https://lkml.kernel.org/r/20220706161231.085a83da@gandalf.local.home
Reported-by: Sascha Hauer <sha@pengutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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If you drop into kdb and type "ftdump" you'll get a sleeping while
atomic warning from memory allocation in trace_find_next_entry().
This appears to have been caused by commit ff895103a84a ("tracing:
Save off entry when peeking at next entry"), which added the
allocation in that path. The problematic commit was already fixed by
commit 8e99cf91b99b ("tracing: Do not allocate buffer in
trace_find_next_entry() in atomic") but that fix missed the kdb case.
The fix here is easy: just move the assignment of the static buffer to
the place where it should have been to begin with:
trace_init_global_iter(). That function is called in two places, once
is right before the assignment of the static buffer added by the
previous fix and once is in kdb.
Note that it appears that there's a second static buffer that we need
to assign that was added in commit efbbdaa22bb7 ("tracing: Show real
address for trace event arguments"), so we'll move that too.
Link: https://lkml.kernel.org/r/20220708170919.1.I75844e5038d9425add2ad853a608cb44bb39df40@changeid
Fixes: ff895103a84a ("tracing: Save off entry when peeking at next entry")
Fixes: efbbdaa22bb7 ("tracing: Show real address for trace event arguments")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Namhyung Kim
Andi Kleen
Linus Torvalds
Mathieu Desnoyers
Waiman Long
Lai Jiangshan
David Howells
Thomas Gleixner
Lukas Bulwahn
Marc Zyngier
Cruz Zhao
Nicolas Saenz Julienne
Juri Lelli
Paran Lee
Jianmin Lv
Neeraj Upadhyay
Paul E. McKenney
Xu Qiang
Petr Mladek
John Ogness
Muchun Song
Coiby Xu
Kuniyuki Iwashima
John Keeping
Vincent Guittot
Peter Zijlstra
Steven Rostedt (Google)
Douglas Anderson