Paul E. McKenney
cda27a2c6d
rcu: Don't deboost before reporting expedited quiescent state ...
commit 10c535787436d62ea28156a4b91365fd89b5a432 upstream.
Currently rcu_preempt_deferred_qs_irqrestore() releases rnp->boost_mtx
before reporting the expedited quiescent state. Under heavy real-time
load, this can result in this function being preempted before the
quiescent state is reported, which can in turn prevent the expedited grace
period from completing. Tim Murray reports that the resulting expedited
grace periods can take hundreds of milliseconds and even more than one
second, when they should normally complete in less than a millisecond.
This was fine given that there were no particular response-time
constraints for synchronize_rcu_expedited(), as it was designed
for throughput rather than latency. However, some users now need
sub-100-millisecond response-time constratints.
This patch therefore follows Neeraj's suggestion (seconded by Tim and
by Uladzislau Rezki) of simply reversing the two operations.
Reported-by: Tim Murray <timmurray@google.com>
Reported-by: Joel Fernandes <joelaf@google.com>
Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Tested-by: Tim Murray <timmurray@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: <stable@vger.kernel.org> # 5.4.x
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-03-28 08:46:48 +02:00
bpf: Add kconfig knob for disabling unpriv bpf by default
2022-02-16 12:52:49 +01:00
cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
2022-03-02 11:41:00 +01:00
kdb: Make memory allocations more robust
2021-03-04 10:26:10 +01:00
dma-debug: fix sg checks in debug_dma_map_sg()
2021-10-27 09:54:25 +02:00
perf: Fix list corruption in perf_cgroup_switch()
2022-02-16 12:52:53 +01:00
gcov: re-fix clang-11+ support
2021-04-14 08:24:10 +02:00
genirq/timings: Fix error return code in irq_timings_test_irqs()
2021-09-15 09:47:29 +02:00
locking/lockdep: Avoid RCU-induced noinstr fail
2021-11-17 09:48:28 +01:00
PM: s2idle: ACPI: Fix wakeup interrupts handling
2022-02-16 12:52:50 +01:00
printk/console: Allow to disable console output by using console="" or console=null
2021-11-12 14:43:03 +01:00
rcu: Don't deboost before reporting expedited quiescent state
2022-03-28 08:46:48 +02:00
sched/topology: Fix sched_domain_topology_level alloc in sched_init_numa()
2022-03-08 19:07:48 +01:00
timekeeping: Really make sure wall_to_monotonic isn't positive
2021-12-22 09:29:39 +01:00
tracing: Ensure trace buffer is at least 4096 bytes large
2022-03-16 13:21:47 +01:00
kbuild: update config_data.gz only when the content of .config is changed
2021-05-11 14:04:16 +02:00
Revert "module, async: async_synchronize_full() on module init iff async is used"
2022-02-23 11:59:56 +01:00
audit: improve audit queue handling when "audit=1" on cmdline
2022-02-08 18:24:26 +01:00
audit: fix a net reference leak in audit_list_rules_send()
2020-06-22 09:30:59 +02:00
audit: move put_tree() to avoid trim_trees refcount underflow and UAF
2021-09-03 10:08:16 +02:00
audit: CONFIG_CHANGE don't log internal bookkeeping as an event
2020-10-01 13:17:32 +02:00
audit: fix a net reference leak in audit_list_rules_send()
2020-06-22 09:30:59 +02:00
audit: fix possible null-pointer dereference in audit_filter_rules
2021-10-27 09:54:27 +02:00
cpu/hotplug: Cure the cpusets trainwreck
2021-07-19 08:53:15 +02:00
kernel/cpu_pm: Fix uninitted local in cpu_pm
2020-06-22 09:31:22 +02:00
don't dump the threads that had been already exiting when zapped.
2020-11-18 19:20:31 +01:00
fail_function: Remove a redundant mutex unlock
2020-11-24 13:29:18 +01:00
copy_process(): Move fd_install() out of sighand->siglock critical section
2022-02-23 12:00:00 +01:00
mm, futex: fix shared futex pgoff on shmem huge page
2021-06-30 08:47:55 -04:00
kbuild: add variables for compression tools
2020-09-03 11:27:10 +02:00
kallsyms: Refactor kallsyms_show_value() to take cred
2020-07-16 08:16:44 +02:00
exec: Transform exec_update_mutex into a rw_semaphore
2021-01-09 13:44:55 +01:00
kernel: kexec: remove the lock operation of system_transition_mutex
2021-02-03 23:25:56 +01:00
kernel: kexec_file: fix error return code of kexec_calculate_store_digests()
2021-05-19 10:08:28 +02:00
kmod: make request_module() return an error when autoloading is disabled
2020-04-17 10:50:22 +02:00
kprobes: Limit max data_size of the kretprobe instances
2021-12-08 09:01:10 +01:00
kthread: Fix PF_KTHREAD vs to_kthread() race
2021-09-12 08:56:39 +02:00
kbuild: update config_data.gz only when the content of .config is changed
2021-05-11 14:04:16 +02:00
module/ftrace: handle patchable-function-entry
2022-02-23 11:59:56 +01:00
module: harden ELF info handling
2021-04-07 14:47:38 +02:00
module: harden ELF info handling
2021-04-07 14:47:38 +02:00
kernel/notifier.c: intercept duplicate registrations to avoid infinite loops
2020-10-01 13:17:23 +02:00
padata: add separate cpuhp node for CPUHP_PADATA_DEAD
2020-06-17 16:40:22 +02:00
memcg: enable accounting for pids in nested pid namespaces
2021-09-22 12:26:37 +02:00
profiling: fix shift-out-of-bounds bugs
2021-09-26 14:07:09 +02:00
ptrace: make ptrace() fail if the tracee changed its pid unexpectedly
2021-05-26 12:05:15 +02:00
reboot: fix overflow parsing reboot cpu number
2020-11-18 19:20:30 +01:00
kernel/relay.c: fix memleak on destroy relay channel
2020-08-26 10:40:51 +02:00
/dev/mem: Revoke mappings when a driver claims the region
2020-06-24 17:50:35 +02:00
seccomp: Invalidate seccomp mode to catch death failures
2022-02-16 12:52:53 +01:00
signal: Remove the bogus sigkill_pending in ptrace_stop
2021-11-17 09:48:24 +01:00
smp: Fix smp_call_function_single_async prototype
2021-05-14 09:44:33 +02:00
kthread: Extract KTHREAD_IS_PER_CPU
2021-02-07 15:35:49 +01:00
prctl: allow to setup brk for et_dyn executables
2021-09-26 14:07:08 +02:00
kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()
2020-10-01 13:17:10 +02:00
x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting
2022-03-11 11:22:37 +01:00
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
2021-07-14 16:53:08 +02:00
taskstats: Cleanup the use of task->exit_code
2022-02-23 11:59:57 +01:00
usermodehelper: reset umask to default before executing user process
2020-10-14 10:32:58 +02:00
smp: Fix smp_call_function_single_async prototype
2021-05-14 09:44:33 +02:00
workqueue: Fix unbind_workers() VS wq_worker_running() race
2022-01-16 09:15:38 +01:00
cda27a2c6d