Peter Zijlstra f506ed5538 sched/core: Avoid spurious lock dependencies ...

[ Upstream commit ff51ff84d82aea5a889b85f2b9fb3aa2b8691668 ]

While seemingly harmless, __sched_fork() does hrtimer_init(), which,
when DEBUG_OBJETS, can end up doing allocations.

This then results in the following lock order:

  rq->lock
    zone->lock.rlock
      batched_entropy_u64.lock

Which in turn causes deadlocks when we do wakeups while holding that
batched_entropy lock -- as the random code does.

Solve this by moving __sched_fork() out from under rq->lock. This is
safe because nothing there relies on rq->lock, as also evident from the
other __sched_fork() callsite.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: bigeasy@linutronix.de
Cc: cl@linux.com
Cc: keescook@chromium.org
Cc: penberg@kernel.org
Cc: rientjes@google.com
Cc: thgarnie@google.com
Cc: tytso@mit.edu
Cc: will@kernel.org
Fixes: b7d5dc21072c ("random: add a spinlock_t to struct batched_entropy")
Link: https://lkml.kernel.org/r/20191001091837.GK4536@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2019-12-17 20:37:29 +01:00

..

autogroup.c

sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]

2018-05-16 10:10:30 +02:00

autogroup.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

clock.c

sched/clock: Fix early boot preempt assumption in __set_sched_clock_stable()

2017-05-24 09:10:00 +02:00

completion.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

core.c

sched/core: Avoid spurious lock dependencies

2019-12-17 20:37:29 +01:00

cpuacct.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

cpuacct.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

cpudeadline.c

sched/deadline: Change return value of cpudl_find()

2017-08-10 12:18:17 +02:00

cpudeadline.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

cpufreq_schedutil.c

sched/cpufreq: Fix kobject memleak

2019-05-25 18:25:36 +02:00

cpufreq.c

cpufreq / sched: Pass flags to cpufreq_update_util()

2016-08-16 22:14:55 +02:00

cpupri.c

sched/cpupri: Don't re-initialize 'struct cpupri'

2017-08-10 12:18:14 +02:00

cpupri.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

cputime.c

sched/vtime: Fix guest/system mis-accounting on task switch

2019-11-06 12:43:16 +01:00

deadline.c

sched/deadline: Correctly handle active 0-lag timers

2019-05-02 09:40:32 +02:00

debug.c

sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK

2019-04-05 22:31:36 +02:00

fair.c

sched/fair: Don't increase sd->balance_interval on newidle balance

2019-12-01 09:14:02 +01:00

features.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

idle_task.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

idle.c

PM / s2idle: Rename ->enter_freeze to ->enter_s2idle

2017-08-11 01:29:56 +02:00

loadavg.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

Makefile

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

membarrier.c

membarrier: Disable preemption when calling smp_call_function_many()

2018-01-17 09:45:23 +01:00

rt.c

sched/rt: Check integer overflow at usec to nsec conversion

2019-05-31 06:47:26 -07:00

sched-pelt.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

sched.h

sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices

2019-11-12 19:18:29 +01:00

stats.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

stats.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

stop_task.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

swait.c

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

topology.c

sched/topology: Fix off by one bug

2019-12-01 09:14:02 +01:00

wait_bit.c

sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming

2017-06-20 12:19:14 +02:00

wait.c

sched/core: Use smp_mb() in wake_woken_function()

2018-09-26 08:38:10 +02:00