linux/kernel/sched
Hao Jia 5ebde09d91 sched/core: Fix RQCF_ACT_SKIP leak
Igor Raits and Bagas Sanjaya report a RQCF_ACT_SKIP leak warning.

This warning may be triggered in the following situations:

    CPU0                                      CPU1

__schedule()
  *rq->clock_update_flags <<= 1;*   unregister_fair_sched_group()
  pick_next_task_fair+0x4a/0x410      destroy_cfs_bandwidth()
    newidle_balance+0x115/0x3e0       for_each_possible_cpu(i) *i=0*
      rq_unpin_lock(this_rq, rf)      __cfsb_csd_unthrottle()
      raw_spin_rq_unlock(this_rq)
                                      rq_lock(*CPU0_rq*, &rf)
                                      rq_clock_start_loop_update()
                                      rq->clock_update_flags & RQCF_ACT_SKIP <--
      raw_spin_rq_lock(this_rq)

The purpose of RQCF_ACT_SKIP is to skip the update rq clock,
but the update is very early in __schedule(), but we clear
RQCF_*_SKIP very late, causing it to span that gap above
and triggering this warning.

In __schedule() we can clear the RQCF_*_SKIP flag immediately
after update_rq_clock() to avoid this RQCF_ACT_SKIP leak warning.
And set rq->clock_update_flags to RQCF_UPDATED to avoid
rq->clock_update_flags < RQCF_ACT_SKIP warning that may be triggered later.

Fixes: ebb83d84e4 ("sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()")
Closes: https://lore.kernel.org/all/20230913082424.73252-1-jiahao.os@bytedance.com
Reported-by: Igor Raits <igor.raits@gmail.com>
Reported-by: Bagas Sanjaya <bagasdotme@gmail.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Hao Jia <jiahao.os@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/a5dd536d-041a-2ce9-f4b7-64d8d85c86dc@gmail.com
2023-10-24 10:38:42 +02:00
..
autogroup.c
autogroup.h
build_policy.c
build_utility.c sched/headers: Remove duplicate header inclusions 2023-10-03 21:27:55 +02:00
clock.c Locking changes for v6.5: 2023-06-27 14:14:30 -07:00
completion.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
core_sched.c
core.c sched/core: Fix RQCF_ACT_SKIP leak 2023-10-24 10:38:42 +02:00
cpuacct.c
cpudeadline.c sched/topology: Consolidate and clean up access to a CPU's max compute capacity 2023-10-09 12:59:48 +02:00
cpudeadline.h
cpufreq_schedutil.c cpufreq: schedutil: Update next_freq when cpufreq_limits change 2023-10-05 22:09:50 +02:00
cpufreq.c
cpupri.c sched/rt: Fix live lock between select_fallback_rq() and RT push 2023-09-28 22:58:13 +02:00
cpupri.h
cputime.c
deadline.c sched: Fix stop_one_cpu_nowait() vs hotplug 2023-10-13 09:56:29 +02:00
debug.c sched/deadline: Make dl_rq->pushable_dl_tasks update drive dl_rq->overloaded 2023-09-29 10:20:21 +02:00
fair.c Linux 6.6-rc7 2023-10-23 11:32:25 +02:00
features.h sched/eevdf: Curb wakeup-preemption 2023-08-17 17:07:07 +02:00
idle.c Merge branch 'sched/urgent' into sched/core, to pick up fixes and refresh the branch 2023-10-07 11:32:24 +02:00
isolation.c
loadavg.c
Makefile
membarrier.c
pelt.c sched: Make PELT acronym definition searchable 2023-10-13 09:56:30 +02:00
pelt.h
psi.c sched/psi: Update poll => rtpoll in relevant comments 2023-10-16 13:42:49 +02:00
rt.c sched: Fix stop_one_cpu_nowait() vs hotplug 2023-10-13 09:56:29 +02:00
sched-pelt.h
sched.h sched/headers: Remove comment referring to rq::cpu_load, since this has been removed 2023-10-10 23:42:20 +02:00
smp.h sched, smp: Trace smp callback causing an IPI 2023-03-24 11:01:29 +01:00
stats.c
stats.h
stop_task.c sched/fair: Rename check_preempt_curr() to wakeup_preempt() 2023-09-19 10:40:10 +02:00
swait.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00
topology.c sched/topology: Rename 'DIE' domain to 'PKG' 2023-10-12 09:38:16 +02:00
wait_bit.c
wait.c sched: add a few helpers to wake up tasks on the current cpu 2023-07-17 16:08:08 -07:00