On Wed, Nov 30, 2016 at 11:56:53AM +0100, Petr Mladek wrote: > On Wed 2016-11-30 15:15:19, [email protected] wrote: > > In arm, arm64, x86 or other architecture, spinlock variable
x86 no longer uses ticket locks. > > The solution is that In function zap_locks(), replace > > raw_spin_lock_init(&logbuf_lock) with raw_spin_unlock(&logbuf_lock), That's broken too. Imagine the CPU that actually holds the lock then _also_ doing an unlock. At that point the tail is ahead of the head and you're also up some creek without no paddle. Note that I ran into all these scenarios many years ago.. > Another solution would be to make printk() to ignore locks > when Oops is in progress. It was somewhere suggested by Peter > Zijlstra. Well, it might cause some problems as well when > there are more CPUs still running and printing. Ignoring is the only option. There is no way to fudge the lock state and live to tell about it.
