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Tejun Heo 3296682157 sched_ext: Fix migration disabled handling in targeted dispatches 
A dispatch operation that can target a specific local DSQ -
scx_bpf_dsq_move_to_local() or scx_bpf_dsq_move() - checks whether the task
can be migrated to the target CPU using task_can_run_on_remote_rq(). If the
task can't be migrated to the targeted CPU, it is bounced through a global
DSQ.

task_can_run_on_remote_rq() assumes that the task is on a CPU that's
different from the targeted CPU but the callers doesn't uphold the
assumption and may call the function when the task is already on the target
CPU. When such task has migration disabled, task_can_run_on_remote_rq() ends
up returning %false incorrectly unnecessarily bouncing the task to a global
DSQ.

Fix it by updating the callers to only call task_can_run_on_remote_rq() when
the task is on a different CPU than the target CPU. As this is a bit subtle,
for clarity and documentation:

- Make task_can_run_on_remote_rq() trigger SCHED_WARN_ON() if the task is on
  the same CPU as the target CPU.

- is_migration_disabled() test in task_can_run_on_remote_rq() cannot trigger
  if the task is on a different CPU than the target CPU as the preceding
  task_allowed_on_cpu() test should fail beforehand. Convert the test into
  SCHED_WARN_ON().

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 4c30f5ce4f ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()")
Fixes: 0366017e09 ("sched_ext: Use task_can_run_on_remote_rq() test in dispatch_to_local_dsq()")
Cc: stable@vger.kernel.org # v6.12+
2025-02-08 20:33:25 -10:00
..
bpf bpf-next-6.14 2025-01-23 08:04:07 -08:00
cgroup drm next for 6.14-rc1 2025-01-21 16:09:47 -08:00
configs configs/debug: make sure PROVE_RCU_LIST=y takes effect 2024-10-28 10:21:09 -07:00
debug kdb: fix ctrl+e/a/f/b/d/p/n broken in keyboard mode 2024-11-18 15:20:22 +00:00
dma dma-debug: fix physical address calculation for struct dma_debug_entry 2024-11-28 10:19:16 +01:00
entry sched: Add TIF_NEED_RESCHED_LAZY infrastructure 2024-11-05 12:55:37 +01:00
events Performance events changes for v6.14: 2025-01-21 10:52:03 -08:00
futex sched/wake_q: Add helper to call wake_up_q after unlock with preemption disabled 2024-12-20 15:31:21 +01:00
gcov gcov: add support for GCC 14 2024-06-15 10:43:06 -07:00
irq Updates for the interrupt subsystem: 2025-01-21 13:51:07 -08:00
kcsan kcsan: Remove redundant call of kallsyms_lookup_name() 2024-10-14 16:44:56 +02:00
livepatch livepatch: Add stack_order sysfs attribute 2024-12-09 11:44:03 +01:00
locking RCU pull request for v6.14 2025-01-21 14:39:21 -08:00
module module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
power Merge branches 'pm-sleep', 'pm-cpuidle' and 'pm-em' 2025-01-20 19:14:15 +01:00
printk Merge branch 'for-6.14-cpu_sync-fixup' into for-linus 2025-01-20 13:40:52 +01:00
rcu Kthreads affinity follow either of 4 existing different patterns: 2025-01-21 17:10:05 -08:00
sched sched_ext: Fix migration disabled handling in targeted dispatches 2025-02-08 20:33:25 -10:00
time Updates for timers and timekeeping: 2025-01-21 13:16:00 -08:00
trace Fix atomic64 operations on some architectures for the tracing ring buffer: 2025-01-23 18:02:55 -08:00
.gitignore
acct.c acct: avoid pointless reference count bump 2024-12-02 11:25:13 +01:00
async.c async: Use a dedicated unbound workqueue with raised min_active 2024-02-09 11:13:59 -10:00
audit.c lsm: replace context+len with lsm_context 2024-12-04 14:42:31 -05:00
audit.h audit: change context data from secid to lsm_prop 2024-10-11 14:34:16 -04:00
audit_fsnotify.c
audit_tree.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
audit_watch.c fsnotify: create a wrapper fsnotify_find_inode_mark() 2024-04-04 16:24:16 +02:00
auditfilter.c audit: fix suffixed '/' filename matching 2024-12-05 19:22:38 -05:00
auditsc.c lsm/stable-6.14 PR 20250121 2025-01-21 20:03:04 -08:00
backtracetest.c backtracetest: add MODULE_DESCRIPTION() 2024-06-24 22:24:55 -07:00
bounds.c bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS 2024-04-29 08:29:29 -07:00
capability.c lsm: constify the 'target' parameter in security_capget() 2023-08-08 16:48:47 -04:00
cfi.c
compat.c
configs.c
context_tracking.c context_tracking, rcu: Rename rcu_dyntick trace event into rcu_watching 2024-08-15 21:30:43 +05:30
cpu.c hrtimers: Handle CPU state correctly on hotplug 2025-01-16 13:06:14 +01:00
cpu_pm.c
crash_core.c kexec/crash: no crash update when kexec in progress 2024-11-05 17:12:27 -08:00
crash_reserve.c crash: fix crash memory reserve exceed system memory bug 2024-09-01 20:43:30 -07:00
cred.c cred: remove old {override,revert}_creds() helpers 2024-12-02 11:25:09 +01:00
delayacct.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
dma.c
elfcorehdr.c crash: remove dependency of FA_DUMP on CRASH_DUMP 2024-02-23 17:48:22 -08:00
exec_domain.c
exit.c remove pointless includes of <linux/fdtable.h> 2024-10-07 13:34:41 -04:00
exit.h exit: add internal include file with helpers 2023-09-21 12:03:50 -06:00
extable.c
fail_function.c
fork.c \n 2025-01-23 13:36:06 -08:00
freezer.c sched/fair: Fix external p->on_rq users 2024-10-14 09:14:35 +02:00
gen_kheaders.sh kheaders: Ignore silly-rename files 2024-12-20 22:07:55 +01:00
groups.c groups: Convert group_info.usage to refcount_t 2023-09-29 11:28:39 -07:00
hung_task.c hung_task: add detect count for hung tasks 2024-11-11 17:17:03 -08:00
iomem.c kernel/iomem.c: remove __weak ioremap_cache helper 2023-08-21 13:37:28 -07:00
irq_work.c
jump_label.c jump_label: Fix static_key_slow_dec() yet again 2024-09-10 11:57:27 +02:00
kallsyms.c kallsyms: Match symbols exactly with CONFIG_LTO_CLANG 2024-08-15 09:33:35 -07:00
kallsyms_internal.h kallsyms: get rid of code for absolute kallsyms 2024-07-20 16:33:21 +09:00
kallsyms_selftest.c kallsyms: Use kthread_run_on_cpu() 2025-01-02 22:12:12 +01:00
kallsyms_selftest.h
kcmp.c get rid of ...lookup...fdget_rcu() family 2024-10-07 13:34:41 -04:00
Kconfig.freezer
Kconfig.hz
Kconfig.kexec crash, powerpc: default to CRASH_DUMP=n on PPC_BOOK3S_32 2024-11-14 22:43:48 -08:00
Kconfig.locks
Kconfig.preempt sched: No PREEMPT_RT=y for all{yes,mod}config 2024-11-07 15:25:05 +01:00
kcov.c kcov: mark in_softirq_really() as __always_inline 2024-12-30 17:59:08 -08:00
kexec.c crash: add a new kexec flag for hotplug support 2024-04-23 14:59:01 +10:00
kexec_core.c kexec_core: Add and update comments regarding the KEXEC_JUMP flow 2025-01-14 13:03:34 +01:00
kexec_elf.c
kexec_file.c kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y 2024-09-01 17:59:01 -07:00
kexec_internal.h kexec: use atomic_try_cmpxchg_acquire() in kexec_trylock() 2024-09-01 20:43:23 -07:00
kheaders.c
kprobes.c kprobes: Remove remaining gotos 2025-01-10 09:00:13 +09:00
ksyms_common.c
ksysfs.c profiling: remove prof_cpu_mask 2024-07-29 10:45:54 -07:00
kthread.c Kthreads affinity follow either of 4 existing different patterns: 2025-01-21 17:10:05 -08:00
latencytop.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
Makefile mm: move kernel/numa.c to mm/ 2024-09-03 21:15:26 -07:00
module_signature.c
notifier.c reboot: move reboot_notifier_list to kernel/reboot.c 2024-11-05 17:12:31 -08:00
nsproxy.c fdget(), trivial conversions 2024-11-03 01:28:06 -05:00
padata.c padata: avoid UAF for reorder_work 2025-01-19 12:44:28 +08:00
panic.c drm next for 6.12-rc1 2024-09-19 10:18:15 +02:00
params.c params: Fix multi-line comment style 2023-12-01 09:51:44 -08:00
pid.c kernel-6.14-rc1.pid 2025-01-20 10:29:11 -08:00
pid_namespace.c pid: allow pid_max to be set per pid namespace 2024-12-02 11:25:25 +01:00
pid_sysctl.h sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
profile.c profiling: remove profile=sleep support 2024-08-04 13:36:28 -07:00
ptrace.c ptrace_attach: shift send(SIGSTOP) into ptrace_set_stopped() 2024-02-22 15:38:52 -08:00
range.c
reboot.c kernel/reboot: replace sprintf() with sysfs_emit() 2024-11-11 17:17:05 -08:00
regset.c regset: use kvzalloc() for regset_get_alloc() 2024-04-25 21:07:03 -07:00
relay.c [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
resource.c module: Convert symbol namespace to string literal 2024-12-02 11:34:44 -08:00
resource_kunit.c resource, kunit: fix user-after-free in resource_test_region_intersects() 2024-10-09 12:47:19 -07:00
rseq.c rseq: Fix rseq unregistration regression 2025-01-21 08:10:51 +01:00
scftorture.c scftorture: Handle NULL argument passed to scf_add_to_free_list(). 2024-11-14 16:09:51 -08:00
scs.c
seccomp.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
signal.c signal/posixtimers: Handle ignore/blocked sequences correctly 2025-01-15 18:08:01 +01:00
smp.c smp/scf: Evaluate local cond_func() before IPI side-effects 2024-12-05 14:25:28 +01:00
smpboot.c kthread: add kthread_stop_put 2023-10-04 10:41:57 -07:00
smpboot.h
softirq.c softirq: Allow raising SCHED_SOFTIRQ from SMP-call-function on RT kernel 2024-12-02 12:01:27 +01:00
stackleak.c stackleak: Use str_enabled_disabled() helper in stack_erasing_sysctl() 2024-12-22 20:28:11 -08:00
stacktrace.c stacktrace: fix kernel-doc typo 2023-12-29 12:22:29 -08:00
static_call.c
static_call_inline.c x86/static-call: provide a way to do very early static-call updates 2024-12-13 09:28:32 +01:00
stop_machine.c rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs() 2024-08-15 21:30:42 +05:30
sys.c tracing: Add task_prctl_unknown tracepoint 2024-12-22 20:28:11 -08:00
sys_ni.c Probes updates for v6.11: 2024-07-18 12:19:20 -07:00
sysctl-test.c sysctl: Add module description to sysctl-testing 2024-06-03 15:20:37 +02:00
sysctl.c pid: allow pid_max to be set per pid namespace 2024-12-02 11:25:25 +01:00
task_work.c sched/core: Disable page allocation in task_tick_mm_cid() 2024-10-11 10:49:32 +02:00
taskstats.c fdget(), more trivial conversions 2024-11-03 01:28:06 -05:00
torture.c torture: Add MODULE_DESCRIPTION() 2024-05-30 15:31:38 -07:00
tracepoint.c tracing: Fix syscall tracepoint use-after-free 2024-11-01 14:37:31 -04:00
tsacct.c tsacct: replace strncpy() with strscpy() 2024-07-12 16:39:53 -07:00
ucount.c Summary 2024-11-22 20:36:11 -08:00
uid16.c
uid16.h
umh.c remove pointless includes of <linux/fdtable.h> 2024-10-07 13:34:41 -04:00
up.c smp: Change function signatures to use call_single_data_t 2023-09-13 14:59:24 +02:00
user-return-notifier.c
user.c uidgid: make sure we fit into one cacheline 2024-09-12 12:16:09 +02:00
user_namespace.c user_namespace: use kmemdup_array() instead of kmemdup() for multiple allocation 2024-09-09 16:47:42 -07:00
usermode_driver.c
utsname.c
utsname_sysctl.c sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
vhost_task.c vhost_task: Handle SIGKILL by flushing work and exiting 2024-05-22 08:31:15 -04:00
vmcore_info.c mm: support only one page_type per page 2024-09-03 21:15:43 -07:00
watch_queue.c watch_queue: Use page->private instead of page->index 2024-12-22 11:29:51 +01:00
watchdog.c - The series "resource: A couple of cleanups" from Andy Shevchenko 2024-11-25 16:09:48 -08:00
watchdog_buddy.c
watchdog_perf.c watchdog/perf: properly initialize the turbo mode timestamp and rearm counter 2024-07-17 21:11:34 -07:00
workqueue.c Kthreads affinity follow either of 4 existing different patterns: 2025-01-21 17:10:05 -08:00
workqueue_internal.h workqueue: Drop the special locking rule for worker->flags and worker_pool->flags 2023-08-07 15:57:22 -10:00