Peter Zijlstra f7757368e0 sched/core: Fix illegal RCU from offline CPUs ... [ Upstream commit bf2c59fce4 ] 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 09:31:01 +02:00
..
autogroup.h	…
clock.h	…
coredump.h	oom, oom_reaper: do not enqueue same task twice	2019-02-01 15:46:23 -08:00
cpufreq.h	cpufreq: Avoid leaving stale IRQ work items during CPU offline	2019-12-31 16:46:06 +01:00
cputime.h	posix-cpu-timers: Move state tracking to struct posix_cputimers	2019-08-28 11:50:42 +02:00
deadline.h	cpusets: Rebuild root domain deadline accounting information	2019-07-25 15:55:01 +02:00
debug.h	…
hotplug.h	…
idle.h	…
init.h	…
isolation.h	KVM: LAPIC: Inject timer interrupt via posted interrupt	2019-07-20 09:00:40 +02:00
jobctl.h	cgroup: cgroup v2 freezer	2019-04-19 11:26:48 -07:00
loadavg.h	…
mm.h	sched/core: Fix illegal RCU from offline CPUs	2020-06-22 09:31:01 +02:00
nohz.h	timers/nohz: Update NOHZ load in remote tick	2020-03-05 16:43:36 +01:00
numa_balancing.h	sched/fair: Don't free p->numa_faults with concurrent readers	2019-07-25 15:37:04 +02:00
prio.h	…
rt.h	…
signal.h	posix-cpu-timers: Move state tracking to struct posix_cputimers	2019-08-28 11:50:42 +02:00
smt.h	…
stat.h	…
sysctl.h	sched/uclamp: Add system default clamps	2019-06-24 19:23:45 +02:00
task.h	tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code	2019-09-25 17:42:29 +02:00
task_stack.h	sched/core: Convert task_struct.stack_refcount to refcount_t	2019-02-04 08:53:56 +01:00
topology.h	sched/topology: Add partition_sched_domains_locked()	2019-07-25 15:51:57 +02:00
types.h	posix-cpu-timers: Provide array based access to expiry cache	2019-08-28 11:50:35 +02:00
user.h	keys: Move the user and user-session keyrings to the user_namespace	2019-06-26 21:02:32 +01:00
wake_q.h	locking/rwsem: Always release wait_lock before waking up tasks	2019-06-17 12:28:00 +02:00
xacct.h	…