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