Re: [patch 3/3] mm: fault handler to replace nopage and populate

Nick Piggin
2006-10-08T02:12:42Z

Andrew Morton wrote:

>- You may find that gcc generates crap code for the initialisation of the
> `struct fault_data'. If so, filling the fields in by hand one-at-a-time
> will improve things.
>

OK.

>- So is the plan here to migrate all code over to using
> vm_operations.fault() and to finally remove vm_operations.nopage and
> .nopfn? If so, that'd be nice.
>

Definitely remove .nopage, .populate, and hopefully .page_mkwrite.

.nopfn is a little harder because it doesn't quite follow the same pattern
as the others (eg. has no struct page).

>- As you know, there is a case for constructing that `struct fault_data'
> all the way up in do_no_page(): so we can pass data back, asking
> do_no_page() to rerun the fault if we dropped mmap_sem.
>

That is what it is doing - do_no_page should go away (it is basically
duplicated in __do_fault -- I left it there because I don't know if people
are happy to have a flag day or slowly migrate over).

But I have converted regular pagecache (mm/filemap.c) to use .fault rather
than .nopage and .populate, so you should be able to do the mmap_sem thing
right now. That's something maybe you could look at if you get time? Ie.
whether this .fault handler thing will be sufficient for you.

>- No useful opinion on the substance of this patch, sorry. It's Saturday ;)
>

No hurry. Thanks for the quick initial comments.

--

Send instant messages to your online friends http://au.messenger.yahoo.com