Peter Zijlstra bf2c59fce4 sched/core: Fix illegal RCU from offline CPUs ... 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		2020-04-30 20:14:41 +02:00
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autogroup.h
clock.h
coredump.h
cpufreq.h	sched/fair: Remove redundant call to cpufreq_update_util()	2020-01-17 10:19:22 +01:00
cputime.h
deadline.h
debug.h
hotplug.h
idle.h
init.h
isolation.h	genirq, sched/isolation: Isolate from handling managed interrupts	2020-01-22 16:29:49 +01:00
jobctl.h
loadavg.h
mm.h	sched/core: Fix illegal RCU from offline CPUs	2020-04-30 20:14:41 +02:00
nohz.h	timers/nohz: Update NOHZ load in remote tick	2020-01-28 21:36:44 +01:00
numa_balancing.h
prio.h
rt.h
signal.h	Merge branch 'akpm' (patches from Andrew)	2020-04-02 13:55:34 -07:00
smt.h
stat.h
sysctl.h
task_stack.h
task.h	clone3: allow spawning processes into cgroups	2020-02-12 17:57:51 -05:00
topology.h	sched/topology: Kill SD_LOAD_BALANCE	2020-04-30 20:14:39 +02:00
types.h
user.h
wake_q.h
xacct.h