Re: [PATCH] mm: fix insert_pfn() return value

Måns Rullgård
2018-11-27T15:27:50Z

Matthew Wilcox <willy@infradead.org> writes:

> On Tue, Nov 27, 2018 at 02:43:51PM +0000, Mans Rullgard wrote:
>> Commit 9b5a8e00d479 ("mm: convert insert_pfn() to vm_fault_t") accidentally
>> made insert_pfn() always return an error. Fix this.
>
> Umm. VM_FAULT_NOPAGE is not an error. It's saying "I inserted the PFN,
> there's no struct page for the core VM to do anything with". Which is
> the correct response from a device driver which has called insert_pfn().
>
> Could you explain a bit more what led you to think there's a problem here?

Apparently some (not in mainline) driver code had been hastily converted
to the vm_fault_t codes, and that is where the error is. Sorry for the
noise. Please disregard this.

(The quickest way to get the correct answer is still to send a bad
patch.)

> Also, rather rude of you not to cc the patch author when you claim to
> be fixing a bug in their patch.

Sorry about that. Blame the get-maintainers script.

--
Måns Rullgård