Peter Zijlstra 373491f1f4 sched/core: Fix illegal RCU from offline CPUs ... [ Upstream commit bf2c59fce4074e55d622089b34be3a6bc95484fb ] In the CPU-offline process, it calls mmdrop() after idle entry and the subsequent call to cpuhp_report_idle_dead(). Once execution passes the call to rcu_report_dead(), RCU is ignoring the CPU, which results in lockdep complaining when mmdrop() uses RCU from either memcg or debugobjects below. Fix it by cleaning up the active_mm state from BP instead. Every arch which has CONFIG_HOTPLUG_CPU should have already called idle_task_exit() from AP. The only exception is parisc because it switches them to &init_mm unconditionally (see smp_boot_one_cpu() and smp_cpu_init()), but the patch will still work there because it calls mmgrab(&init_mm) in smp_cpu_init() and then should call mmdrop(&init_mm) in finish_cpu(). WARNING: suspicious RCU usage ----------------------------- kernel/workqueue.c:710 RCU or wq_pool_mutex should be held! other info that might help us debug this: RCU used illegally from offline CPU! Call Trace: dump_stack+0xf4/0x164 (unreliable) lockdep_rcu_suspicious+0x140/0x164 get_work_pool+0x110/0x150 __queue_work+0x1bc/0xca0 queue_work_on+0x114/0x120 css_release+0x9c/0xc0 percpu_ref_put_many+0x204/0x230 free_pcp_prepare+0x264/0x570 free_unref_page+0x38/0xf0 __mmdrop+0x21c/0x2c0 idle_task_exit+0x170/0x1b0 pnv_smp_cpu_kill_self+0x38/0x2e0 cpu_die+0x48/0x64 arch_cpu_idle_dead+0x30/0x50 do_idle+0x2f4/0x470 cpu_startup_entry+0x38/0x40 start_secondary+0x7a8/0xa80 start_secondary_resume+0x10/0x14 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lkml.kernel.org/r/20200401214033.8448-1-cai@lca.pw Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-06-22 09:05:14 +02:00
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autogroup.c
autogroup.h
clock.c
completion.c
core.c	sched/core: Fix illegal RCU from offline CPUs	2020-06-22 09:05:14 +02:00
cpuacct.c
cpudeadline.c
cpudeadline.h
cpufreq.c	cpufreq: Avoid leaving stale IRQ work items during CPU offline	2019-12-31 16:36:22 +01:00
cpufreq_schedutil.c	cpufreq: Avoid leaving stale IRQ work items during CPU offline	2019-12-31 16:36:22 +01:00
cpupri.c
cpupri.h
cputime.c	sched/vtime: Fix guest/system mis-accounting on task switch	2019-11-06 13:06:01 +01:00
deadline.c	sched/deadline: Fix bandwidth accounting at all levels after offline migration	2019-10-05 13:09:36 +02:00
debug.c	jump_label: move 'asm goto' support test to Kconfig	2019-06-04 08:02:34 +02:00
fair.c	sched/fair: Don't NUMA balance for kthreads	2020-06-22 09:05:00 +02:00
features.h
idle.c	idle: Prevent late-arriving interrupts from disrupting offline	2019-10-05 13:09:40 +02:00
isolation.c
loadavg.c
Makefile
membarrier.c	sched/membarrier: Fix private expedited registration check	2019-10-11 18:21:22 +02:00
pelt.c
pelt.h
rt.c	sched/rt: Check integer overflow at usec to nsec conversion	2019-05-31 06:46:19 -07:00
sched-pelt.h	sched/fair: Fix "runnable_avg_yN_inv" not used warnings	2019-07-26 09:14:08 +02:00
sched.h	sched: Avoid scale real weight down to zero	2020-04-17 10:48:40 +02:00
stats.c
stats.h
stop_task.c
swait.c
topology.c	sched/topology: Fix off by one bug	2019-12-01 09:17:16 +01:00
wait.c
wait_bit.c