Messages in this thread | | | Date | Sat, 20 Mar 2004 09:39:51 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: can device drivers return non-ram via vm_ops->nopage? |
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On Sat, 20 Mar 2004, Andrea Arcangeli wrote: > > The only bugreport I've got so far for the latest anon_vma code is from > Jens, and it's a device driver bug in my opinion, but I'd like to have a > definitive confirmation from you about the ->nopage API.
I'd say that this is definitely a driver bug.
If a driver wants to map non-RAM pages, that's perfectly ok, but it MUST NOT happen through "nopage()". The driver should map them with "remap_page_range()", and thus never take a page fault for such pages at all.
There is no reason to ever lazily map non-RAM pages - clearly they aren't using any "real memory", so there is no reason to not fill the page tables at mmap() time.
In other words, the driver is horribly broken.
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