On 12/12/2018 12:04 AM, Sergey Senozhatsky wrote: > On (12/12/18 12:42), Sergey Senozhatsky wrote: > [..] >>>>> [ 87.255156] CPU0 CPU1 >>>>> [ 87.255813] ---- ---- >>>>> [ 87.256460] lock(&port_lock_key); >>>>> [ 87.256973] lock(console_owner); >>>>> [ 87.257829] lock(&port_lock_key); >>>>> [ 87.258680] lock(&obj_hash[i].lock); >> So it's like >> >> CPU0 CPU1 >> >> uart_shutdown() db->lock >> uart_port->lock debug_print_object() >> free_page() printk >> debug_check_no_obj_freed uart_port->lock >> db->lock >> >> >> In this particular case we probably can just move free_page() >> out of uart_port lock scope. Note that free_page()->MM can printk() >> on its own. >> > [..] >> [1] https://lore.kernel.org/lkml/1542653726-5655-8-git-send-email-longman@xxxxxxxxxx/T/#u > That said, I'd first try Waiman's patch. The one I suggested is > more of a defense move - there are too many things happening under > uart_port->lock. This is not the first time we see lockdep complaining > about the way uart and the rest of the kernel interact. > > -ss Thanks for the information. I will extract my debugobjects patch out of my lockdep patchset and send it out as standalone patch. Cheers, Longman
