On Wed, 12 Jun 2019, Soeren Moch wrote: > On 01.06.19 13:02, Sebastian Andrzej Siewior wrote: > > On 2019-06-01 12:50:08 [+0200], To Soeren Moch wrote: > >> I will look into this. > > > > nothing obvious. If there is really blocken lock, could you please > > enable lockdep > > |CONFIG_LOCK_DEBUGGING_SUPPORT=y > > |CONFIG_PROVE_LOCKING=y > > |# CONFIG_LOCK_STAT is not set > > |CONFIG_DEBUG_RT_MUTEXES=y > > |CONFIG_DEBUG_SPINLOCK=y > > |CONFIG_DEBUG_MUTEXES=y > > |CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y > > |CONFIG_DEBUG_RWSEMS=y > > |CONFIG_DEBUG_LOCK_ALLOC=y > > |CONFIG_LOCKDEP=y > > |# CONFIG_DEBUG_LOCKDEP is not set > > |CONFIG_DEBUG_ATOMIC_SLEEP=y > > > > and send me the splat that lockdep will report? > > > > Nothing interesting: > > [ 0.000000] Booting Linux on physical CPU 0x0 > [ 0.000000] Linux version 5.1.0 (root@matrix) (gcc version 7.4.0 > (Debian 7.4.0-6)) #6 SMP PREEMPT Wed Jun 12 11:28:41 CEST 2019 > [ 0.000000] CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), > cr=10c5387d > [ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing > instruction cache > [ 0.000000] OF: fdt: Machine model: TBS2910 Matrix ARM mini PC > ... > [ 0.000000] rcu: Preemptible hierarchical RCU implementation. > [ 0.000000] rcu: RCU lockdep checking is enabled. > ... > [ 0.003546] Lock dependency validator: Copyright (c) 2006 Red Hat, > Inc., Ingo Molnar > [ 0.003657] ... MAX_LOCKDEP_SUBCLASSES: 8 > [ 0.003713] ... MAX_LOCK_DEPTH: 48 > [ 0.003767] ... MAX_LOCKDEP_KEYS: 8191 > [ 0.003821] ... CLASSHASH_SIZE: 4096 > [ 0.003876] ... MAX_LOCKDEP_ENTRIES: 32768 > [ 0.003931] ... MAX_LOCKDEP_CHAINS: 65536 > [ 0.003986] ... CHAINHASH_SIZE: 32768 > [ 0.004042] memory used by lock dependency info: 5243 kB > > Nothing else. > > When stopping hostapd after it hangs: > [ 903.504475] ieee80211 phy0: rt2x00queue_flush_queue: Warning - Queue > 14 failed to flush Instead of reverting the original commit, can you prevent the problem by adding local_irq_save() and local_irq_restore() to the URB completion routines in that wireless driver? Probably people who aren't already pretty familiar with the driver code won't easily be able to locate the race. Still, a little overkill may be an acceptable solution. Alan Stern
