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John Stultz 91839ef7d5 ANDROID: sched: Fix off-by-one with cpupri MAX_RT_PRIO evaluation 
This patch addresses an issue seen where SCHED_FIFO prio 99
tasks were being woken up on a cpu where a long-running softirq
was executing, and the RT task was not being migrated, causing
long (10+ms wakeup latencies).

Prior to upstream commit 934fc3314b39 ("sched/cpupri: Remap
CPUPRI_NORMAL to MAX_RT_PRIO-1") the task->prio -> cpupri
mapping is a little ackward.

For RT tasks, its calculated as:
  cpupri = MAX_RT_PRIO - prio + 1;

See:
https://android.googlesource.com/kernel/common/+/refs/heads/android13-5.10/kernel/sched/cpupri.c#39

This is added ontop of the also ackward detail that the
task->prio is inverted (RT prio99 -> 0), means the cpupri
mapping for RT tasks goes from 2->101. This makes it easy to
evaluate the cpupri incorrectly.

Which it turns out happened In commit 3adfd8e344ac ("ANDROID:
sched: avoid placing RT threads on cores handling softirqs"):
  3adfd8e344%5E%21/

With the lines:
  int task_pri = convert_prio(p->prio);
  bool drop_nopreempts = task_pri <= MAX_RT_PRIO;

Where the added logic to decide to migrate a rt task off of a
cpu depended on this drop_nopreempts being true.

This works properly for rt tasks from prio 99 to 1, but for the
case of task->prio == 0 (userland rt prio 99 tasks) it breaks,
as the cpupri will be MAX_RT_PRIO - 0 + 1, which then gets
checked as <= MAX_RT_PRIO.

This prevents the cpu from being dropped from the scheduling
set and prevents the rt user prio 99 task from migrating, which
results in high priority rt tasks being left on cpus where long
running softirqs are executing, causing long latencies.

This patch fixes the off by one by changing the evaulation
to MAX_RT_PRIO + 1, so that user-prio 99 tasks will also be
migrated if appropriate.

Luckilly this odd cpupri mapping has been fixed upstream, making
this patch no longer necessary in 5.15 and newer kernels.

Fixes: 3adfd8e344ac ("ANDROID: sched: avoid placing RT threads on cores handling softirqs")
Signed-off-by: John Stultz <jstultz@google.com>
Change-Id: Ia2db7cd461eb4c90f5850b791de1ae95582f7530
(cherry picked from commit bec3b2f002cd13d44e32710315de91e636ecef84)
(cherry picked from commit e8e441d4a2f6b6a316d229f8ff1ebe0f40099817)
(cherry picked from commit 1c1f38f1e1fa82e09e0e3f6f941ca81127682ec3)
2024-12-18 15:01:04 +01:00
..
bpf bpf: fix OOB devmap writes when deleting elements 2024-12-17 13:24:29 +01:00
cgroup cgroup/bpf: only cgroup v2 can be attached by bpf programs 2024-12-17 13:24:02 +01:00
configs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
debug kdb: Use the passed prompt in kdb_position_cursor() 2024-11-23 23:20:16 +01:00
dma dma-debug: fix a possible deadlock on radix_lock 2024-12-17 13:24:30 +01:00
entry Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
events Revert "fs,kernel,mm: tune to Ktweak balance" 2024-12-17 20:58:55 +01:00
futex futex: Don't include process MM in futex key on no-MMU 2024-11-18 11:42:47 +01:00
gcov gcov: add support for GCC 14 2024-11-19 14:19:10 +01:00
irq genirq/irqdesc: Honor caller provided affinity in alloc_desc() 2024-11-23 23:20:29 +01:00
kcsan kcsan: Turn report_filterlist_lock into a raw_spinlock 2024-12-17 13:24:29 +01:00
livepatch kallsyms: refactor {,module_}kallsyms_on_each_symbol 2024-11-19 12:27:32 +01:00
locking Revert "rtmutex: Drop rt_mutex::wait_lock before scheduling" 2024-11-24 00:23:36 +01:00
power Reapply "PM / freezer: Reduce freeze timeout to 1 second for Android" 2024-12-18 11:25:17 +01:00
printk printk: Silence useless system log spam 2024-11-19 18:04:40 +01:00
rcu Reapply "rcu: Make the grace period workers unbound again" 2024-12-18 11:24:55 +01:00
sched ANDROID: sched: Fix off-by-one with cpupri MAX_RT_PRIO evaluation 2024-12-18 15:01:04 +01:00
time Reapply "timekeeping: Keep the tick alive when CPUs cycle out of s2idle" 2024-12-18 11:24:12 +01:00
trace tracing: Use atomic64_inc_return() in trace_clock_counter() 2024-12-17 13:24:31 +01:00
acct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
async.c async: Introduce async_schedule_dev_nocall() 2024-11-18 12:12:56 +01:00
audit.c audit: Send netlink ACK before setting connection in auditd_set 2024-11-18 12:13:09 +01:00
audit.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit_fsnotify.c fsnotify: make allow_dups a property of the group 2024-11-19 12:27:55 +01:00
audit_tree.c fsnotify: pass flags argument to fsnotify_alloc_group() 2024-11-19 12:27:55 +01:00
audit_watch.c fsnotify: pass flags argument to fsnotify_alloc_group() 2024-11-19 12:27:55 +01:00
auditfilter.c ima: Avoid blocking in RCU read-side critical section 2024-11-19 14:19:42 +01:00
auditsc.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
backtracetest.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
bounds.c bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS 2024-11-19 11:32:40 +01:00
capability.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cfi.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
compat.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
configs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
context_tracking.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cpu.c cpu: Silence log spam when a CPU is brought up 2024-11-19 18:04:55 +01:00
cpu_pm.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crash_core.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crash_dump.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cred.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
delayacct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dma.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
exec_domain.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
exit.c mm: optimize the redundant loop of mm_update_owner_next() 2024-11-19 14:19:41 +01:00
extable.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fail_function.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fork.c exec: Simplify unshare_files 2024-11-19 12:27:27 +01:00
freezer.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
gen_kheaders.sh kheaders: explicitly define file modes for archived headers 2024-11-19 14:19:30 +01:00
groups.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
hung_task.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
iomem.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
irq_work.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
jump_label.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kallsyms.c Revert "kallsyms: Make kallsyms_on_each_symbol generally available" 2024-11-24 00:22:59 +01:00
kcmp.c kcmp: In get_file_raw_ptr use task_lookup_fd_rcu 2024-11-19 12:27:27 +01:00
Kconfig.freezer Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.hz Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.locks Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.preempt Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kcov.c kcov: don't lose track of remote references during softirqs 2024-11-19 14:19:10 +01:00
kexec.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_core.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_elf.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_file.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kheaders.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kmod.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kprobes.c Revert "x86/ibt,ftrace: Search for __fentry__ location" 2024-11-24 00:23:31 +01:00
ksysfs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kthread.c Revert "kthread: add kthread_work tracepoints" 2024-11-24 00:23:23 +01:00
latencytop.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Makefile kernel: Use the stock defconfig for /proc/config.gz 2024-06-15 16:20:14 -03:00
module-internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
module.c Revert "kallsyms: Make module_kallsyms_on_each_symbol generally available" 2024-11-24 00:22:59 +01:00
module_signature.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
module_signing.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
notifier.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
nsproxy.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
padata.c Revert "padata: Honor the caller's alignment in case of chunk_size 0" 2024-11-24 00:23:30 +01:00
panic.c panic: Flush kernel log buffer at the end 2024-11-19 09:23:11 +01:00
params.c params: lift param_set_uint_minmax to common code 2024-11-19 12:27:09 +01:00
pid.c kernel/pid.c: implement additional checks upon pidfd_create() parameters 2024-11-19 12:27:43 +01:00
pid_namespace.c zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING 2024-11-19 14:19:05 +01:00
profile.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ptrace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
range.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
reboot.c kernel/reboot: emergency_restart: Set correct system_state 2024-11-18 11:43:25 +01:00
regset.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
relay.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
resource.c Revert "resource: fix region_intersects() vs add_memory_driver_managed()" 2024-11-24 00:22:55 +01:00
rseq.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scftorture.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
seccomp.c seccomp: Invalidate seccomp mode to catch death failures 2024-11-18 22:25:35 +01:00
signal.c Revert "signal: Replace BUG_ON()s" 2024-11-24 00:23:07 +01:00
smp.c Reapply "smp: Use migrate disable/enable in smp_call_function_single_async()" 2024-12-18 11:24:48 +01:00
smpboot.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
smpboot.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
softirq.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stackleak.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stacktrace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
static_call.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stop_machine.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sys.c kernel/sys.c: implement custom uname override 2024-11-19 17:55:01 +01:00
sys_ni.c syscalls: fix compat_sys_io_pgetevents_time64 usage 2024-11-19 14:19:34 +01:00
sysctl-test.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sysctl.c Reapply "sysctl: promote several nodes out of CONFIG_SCHED_DEBUG" 2024-12-18 11:25:07 +01:00
task_work.c task_work: Introduce task_work_cancel() again 2024-11-23 23:20:13 +01:00
taskstats.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
test_kprobes.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
torture.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
tracepoint.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
tsacct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ucount.c fanotify: configurable limits via sysfs 2024-11-19 12:27:37 +01:00
uid16.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
uid16.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
umh.c security: samsung: defex_lsm: nuke 2024-06-15 16:20:49 -03:00
up.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user-return-notifier.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user_namespace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
usermode_driver.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
utsname.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
utsname_sysctl.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
watch_queue.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
watchdog.c watchdog: move softlockup_panic back to early_param 2024-11-18 11:43:21 +01:00
watchdog_hld.c watchdog/perf: properly initialize the turbo mode timestamp and rearm counter 2024-11-23 23:20:15 +01:00
workqueue.c Revert "workqueue: Make queue_rcu_work() use call_rcu_flush()" 2024-11-19 18:15:40 +01:00
workqueue_internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00