On Fri, Nov 13, 2020 at 07:05:03PM +0800, Boqun Feng wrote: > A warning was hit when running xfstests/generic/068 in a Hyper-V guest: > > [...] ------------[ cut here ]------------ > [...] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled()) > [...] WARNING: CPU: 2 PID: 1350 at kernel/locking/lockdep.c:5280 check_flags.part.0+0x165/0x170 > [...] ... > [...] Workqueue: events pwq_unbound_release_workfn > [...] RIP: 0010:check_flags.part.0+0x165/0x170 > [...] ... > [...] Call Trace: > [...] lock_is_held_type+0x72/0x150 > [...] ? lock_acquire+0x16e/0x4a0 > [...] rcu_read_lock_sched_held+0x3f/0x80 > [...] __send_ipi_one+0x14d/0x1b0 > [...] hv_send_ipi+0x12/0x30 > [...] __pv_queued_spin_unlock_slowpath+0xd1/0x110 > [...] __raw_callee_save___pv_queued_spin_unlock_slowpath+0x11/0x20 > [...] .slowpath+0x9/0xe > [...] lockdep_unregister_key+0x128/0x180 > [...] pwq_unbound_release_workfn+0xbb/0xf0 > [...] process_one_work+0x227/0x5c0 > [...] worker_thread+0x55/0x3c0 > [...] ? process_one_work+0x5c0/0x5c0 > [...] kthread+0x153/0x170 > [...] ? __kthread_bind_mask+0x60/0x60 > [...] ret_from_fork+0x1f/0x30 > > The cause of the problem is we have call chain lockdep_unregister_key() > -> <irq disabled by raw_local_irq_save()> lockdep_unlock() -> > arch_spin_unlock() -> __pv_queued_spin_unlock_slowpath() -> pv_kick() -> > __send_ipi_one() -> trace_hyperv_send_ipi_one(). > > Although this particular warning is triggered because Hyper-V has a > trace point in ipi sending, but in general arch_spin_unlock() may call > another function having a trace point in it, so put the arch_spin_lock() > and arch_spin_unlock() after lock_recursion protection to fix this > problem and avoid similiar problems. > > Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> Works for me, thanks!
