vm_page_t related KBI [Was: Re: panic at vm_page_wire with FreeBSD 9.0 Beta 3]

Alan Cox alc at rice.edu
Sat Nov 5 20:01:01 UTC 2011

On 11/05/2011 10:15, Kostik Belousov wrote:
> On Sat, Nov 05, 2011 at 07:37:48AM -0700, mdf at freebsd.org wrote:
>> On Sat, Nov 5, 2011 at 7:13 AM, Kostik Belousov<kostikbel at gmail.com>  wrote:
>>> On Fri, Nov 04, 2011 at 06:03:39PM +0200, Kostik Belousov wrote:
>>> Below is the KBI patch after vm_page_bits_t merge is done.
>>> Again, I did not spent time converting all in-tree consumers
>>> from the (potentially) loadable modules to the new KPI until it
>>> is agreed upon.
>> I like my bikeshed orange...
>> I would think a more canonical name would be get/set rather than
>> read/write, especially since these operations aren't reading and
>> writing the page (neither are they getting the page, but at least set
>> is pretty unambiguous).
> Look at the vm_page.h:385. vm_page_set_valid() is already taken.

I don't feel good about creating an interface under which we have 
functions named vm_page_set_valid() and vm_page_write_valid().  I think 
that we should take a step back and look at the whole of set of 
functions that exist for manipulating the page's valid and dirty field 
and see if we can come up with a logical schema for naming them.  I 
wouldn't then be surprised if this results in renaming some of the 
existing functions.

However, this should not delay the changes to address the vm_page_lock 
problem.  I had two questions about that part of your patch.  First, is 
there any reason that you didn't include vm_page_lockptr()?  If we 
created the page locking macros that you, jhb@, and I were talking about 
last week, then vm_page_lockptr() would be required.  Second, there 
seems to be precedent for naming the locking functions _vm_page_lock() 
instead of vm_page_lock_func(), for example, the mutex code, i.e., 
sys/mutex.h, and the vm map locking functions.


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