From: Boqun Feng boqun.feng@gmail.com
[ Upstream commit 43be4388e94b915799a24f0eaf664bf95b85231f ]
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@gmail.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20201113110512.1056501-1-boqun.feng@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/locking/lockdep.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 3eb35ad1b5241..04134a242f3d5 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -108,19 +108,21 @@ static inline void lockdep_lock(void) { DEBUG_LOCKS_WARN_ON(!irqs_disabled());
+ __this_cpu_inc(lockdep_recursion); arch_spin_lock(&__lock); __owner = current; - __this_cpu_inc(lockdep_recursion); }
static inline void lockdep_unlock(void) { + DEBUG_LOCKS_WARN_ON(!irqs_disabled()); + if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current)) return;
- __this_cpu_dec(lockdep_recursion); __owner = NULL; arch_spin_unlock(&__lock); + __this_cpu_dec(lockdep_recursion); }
static inline bool lockdep_assert_locked(void)