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kernel_optimize_test/kernel/sched
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Zhaoyang Huang 6bfcb61789 psi: Fix race between psi_trigger_create/destroy 
[ Upstream commit 8f91efd870ea5d8bc10b0fcc9740db51cd4c0c83 ]

Race detected between psi_trigger_destroy/create as shown below, which
cause panic by accessing invalid psi_system->poll_wait->wait_queue_entry
and psi_system->poll_timer->entry->next. Under this modification, the
race window is removed by initialising poll_wait and poll_timer in
group_init which are executed only once at beginning.

  psi_trigger_destroy()                   psi_trigger_create()

  mutex_lock(trigger_lock);
  rcu_assign_pointer(poll_task, NULL);
  mutex_unlock(trigger_lock);
					  mutex_lock(trigger_lock);
					  if (!rcu_access_pointer(group->poll_task)) {
					    timer_setup(poll_timer, poll_timer_fn, 0);
					    rcu_assign_pointer(poll_task, task);
					  }
					  mutex_unlock(trigger_lock);

  synchronize_rcu();
  del_timer_sync(poll_timer); <-- poll_timer has been reinitialized by
                                  psi_trigger_create()

So, trigger_lock/RCU correctly protects destruction of
group->poll_task but misses this race affecting poll_timer and
poll_wait.

Fixes: 461daba06b ("psi: eliminate kthread_worker from psi trigger scheduling mechanism")
Co-developed-by: ziwei.dai <ziwei.dai@unisoc.com>
Signed-off-by: ziwei.dai <ziwei.dai@unisoc.com>
Co-developed-by: ke.wang <ke.wang@unisoc.com>
Signed-off-by: ke.wang <ke.wang@unisoc.com>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/1623371374-15664-1-git-send-email-huangzhaoyang@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-07-14 16:56:10 +02:00
..
autogroup.c
autogroup.h
clock.c
completion.c
core.c sched/uclamp: Fix uclamp_tg_restrict() 2021-07-14 16:56:10 +02:00
cpuacct.c
cpudeadline.c
cpudeadline.h
cpufreq_schedutil.c
cpufreq.c
cpupri.c
cpupri.h
cputime.c
deadline.c sched/rt: Fix Deadline utilization tracking during policy change 2021-07-14 16:56:09 +02:00
debug.c sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-16 12:01:46 +02:00
fair.c sched/fair: Fix ascii art by relpacing tabs 2021-07-14 16:55:52 +02:00
features.h sched,fair: Alternative sched_slice() 2021-05-11 14:47:31 +02:00
idle.c rcu/nocb: Perform deferred wake up before last idle's need_resched() check 2021-03-04 11:38:35 +01:00
isolation.c
loadavg.c
Makefile
membarrier.c sched/membarrier: fix missing local execution of ipi_sync_rq_state() 2021-03-17 17:06:35 +01:00
pelt.c
pelt.h sched/fair: Fix util_est UTIL_AVG_UNCHANGED handling 2021-06-16 12:01:46 +02:00
psi.c psi: Fix race between psi_trigger_create/destroy 2021-07-14 16:56:10 +02:00
rt.c sched/rt: Fix RT utilization tracking during policy change 2021-07-14 16:56:09 +02:00
sched-pelt.h
sched.h sched/fair: Fix shift-out-of-bounds in load_balance() 2021-05-14 09:50:22 +02:00
smp.h
stats.c
stats.h
stop_task.c
swait.c
topology.c
wait_bit.c
wait.c