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irq_pipeline: lockdep: fix irq state causing deadlock
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Fully disable the irq stage (pipeline-wise) on _every_ operation which
would normally be serialized by raw_local_irq_save(), so that no oob
preemption can occur while holding the inner lockdep __lock. This
fixes a deadlock condition with the following typical backtrace:

(gdb) bt
\#0  0xffffffff81133381 in cpu_relax () at evl-v5.15.y/arch/x86/include/asm/vdso/processor.h:19
\#1  virt_spin_lock (lock=lock@entry=0xffffffff85314090 <__lock>) at evl-v5.15.y/arch/x86/include/asm/qspinlock.h:100
\#2  queued_spin_lock_slowpath (lock=lock@entry=0xffffffff85314090 <__lock>, val=1) at evl-v5.15.y/kernel/locking/qspinlock.c:326
\#3  0xffffffff8112e5e7 in queued_spin_lock (lock=0xffffffff85314090 <__lock>) at evl-v5.15.y/include/asm-generic/qspinlock.h:85
\#4  lockdep_lock () at evl-v5.15.y/kernel/locking/lockdep.c:161
\#5  graph_lock () at evl-v5.15.y/kernel/locking/lockdep.c:187
\#6  mark_lock (curr=0xffff8881002b3100, this=0xffff8881002b3a20, new_bit=new_bit@entry=LOCK_USED_IN_HARDIRQ) at evl-v5.15.y/kernel/locking/lockdep.c:4619
\#7  0xffffffff8112ec2a in mark_usage (curr=curr@entry=0xffff8881002b3100, hlock=hlock@entry=0xffff8881002b3a20, check=check@entry=1) at evl-v5.15.y/kernel/locking/lockdep.c:4530
\#8  0xffffffff8112fae8 in __lock_acquire (lock=lock@entry=0xffffffff825474d8 <rcu_state+24>, subclass=subclass@entry=0, trylock=trylock@entry=0, read=read@entry=0, check=check@entry=1, hardirqs_off=<optimized out>, nest_lock=0x0 <fixed_percpu_data>, ip=18446744071580260235, references=0, pin_count=0) at evl-v5.15.y/kernel/locking/lockdep.c:5013
\#9  0xffffffff8112ed0a in lock_acquire (lock=lock@entry=0xffffffff825474d8 <rcu_state+24>, subclass=subclass@entry=0, trylock=trylock@entry=0, read=read@entry=0, check=check@entry=1, nest_lock=nest_lock@entry=0x0 <fixed_percpu_data>, ip=18446744071580260235) at evl-v5.15.y/kernel/locking/lockdep.c:5677
\#10 0xffffffff81a9ecc5 in __raw_spin_lock_irqsave (lock=0xffffffff825474c0 <rcu_state>) at evl-v5.15.y/include/linux/spinlock_api_smp.h:110
\#11 _raw_spin_lock_irqsave (lock=lock@entry=0xffffffff825474c0 <rcu_state>) at evl-v5.15.y/kernel/locking/spinlock.c:162
\#12 0xffffffff8115978b in print_other_cpu_stall (gp_seq=10445, gps=4294950930) at evl-v5.15.y/kernel/rcu/tree_stall.h:545
\#13 0xffffffff8115f399 in check_cpu_stall (rdp=rdp@entry=0xffff888237dbfb40) at evl-v5.15.y/kernel/rcu/tree_stall.h:729
\#14 0xffffffff8115f476 in rcu_pending (user=user@entry=0) at evl-v5.15.y/kernel/rcu/tree.c:3896
\#15 0xffffffff8115fd05 in rcu_sched_clock_irq (user=0) at evl-v5.15.y/kernel/rcu/tree.c:2614
\#16 0xffffffff8116b013 in update_process_times (user_tick=0) at evl-v5.15.y/kernel/time/timer.c:1788
\#17 0xffffffff8117fae4 in tick_sched_handle (ts=ts@entry=0xffff888237db1da0, regs=regs@entry=0xffff888237dae9e0) at evl-v5.15.y/kernel/time/tick-sched.c:226
\#18 0xffffffff8117fd0f in tick_sched_timer (timer=0xffff888237db1da0) at evl-v5.15.y/kernel/time/tick-sched.c:1420
\#19 0xffffffff8116bb43 in __run_hrtimer (flags=0, now=0xffffc90000200f38, timer=0xffff888237db1da0, base=0xffff888237db1440, cpu_base=0xffff888237db13c0) at evl-v5.15.y/kernel/time/hrtimer.c:1686
\#20 __hrtimer_run_queues (cpu_base=cpu_base@entry=0xffff888237db13c0, now=now@entry=186201588941, flags=flags@entry=0, active_mask=active_mask@entry=15) at evl-v5.15.y/kernel/time/hrtimer.c:1750
\#21 0xffffffff8116cb2e in hrtimer_interrupt (dev=<optimized out>) at evl-v5.15.y/kernel/time/hrtimer.c:1812
\#22 0xffffffff8118188f in proxy_irq_handler (sirq=<optimized out>, dev_id=<optimized out>) at evl-v5.15.y/kernel/time/tick-proxy.c:193
\#23 0xffffffff8114c4fd in handle_synthetic_irq (desc=0xffff888100d1e000) at evl-v5.15.y/kernel/irq/pipeline.c:211
\#24 0xffffffff8105b80b in arch_do_IRQ_pipelined (desc=<optimized out>) at evl-v5.15.y/arch/x86/kernel/irq_pipeline.c:203

This does increase the latency figures even more, but nobody should
expect low latency from a system with lockdep enabled anyway.

Signed-off-by: Philippe Gerum <[email protected]>
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pgerum authored and hao3li committed Sep 19, 2023
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