Re: CVS commit: src/sys/uvm

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Hello,

"Juergen Hannken-Illjes" <hannken%netbsd.org@localhost> wrote:
> Module Name:  src
> Committed By: hannken
> Date:         Fri Jun 17 09:50:52 UTC 2011
> 
> Modified Files:
>       src/sys/uvm: uvm_bio.c
> 
> Log Message:
> When ubc_alloc() reuses a cached mapping window remove the object from
> the lists AFTER clearing its mapping.
> 
> Removes a race where uvm_obj_destroy() sees an empty uo_ubc list and
> destroys the object before ubc_alloc() gets the objects lock to clear
> the mapping.

How is this relevant, since the entries are protected by ubc_object's
lock, which is held across ubc_alloc() and ubc_purge() parts?

-- 
Mindaugas