Dan Williams writes:
> Alistair Popple wrote:
> [..]
>
>> >> > It follows that that the DMA-idle condition still needs to look for the
>> >> > case where the refcount is > 1 rather than 0 since refcount == 1 is the
>> >> > page-mapped-but-DMA-idle condition.
>>
>> Because if the DAX page-cache
Alistair Popple wrote:
[..]
> >> > It follows that that the DMA-idle condition still needs to look for the
> >> > case where the refcount is > 1 rather than 0 since refcount == 1 is the
> >> > page-mapped-but-DMA-idle condition.
>
> Because if the DAX page-cache holds a reference the refcount won
Dan Williams writes:
> Alistair Popple wrote:
> [..]
>>> I'm not really following this scenario, or at least how it relates to
>> >> the comment above. If the page is pinned for DMA it will have taken a
>> >> refcount on it and so the page won't be considered free/idle per
>> >> dax_wait_page_i
Alistair Popple wrote:
[..]
> >
> > Was there a discussion I missed about why the conversion to typical
> > folios allows the page->share accounting to be dropped.
>
> The problem with keeping it is we now treat DAX pages as "normal"
> pages according to vm_normal_page(). As such we use the normal
Alistair Popple wrote:
[..]
>> I'm not really following this scenario, or at least how it relates to
> >> the comment above. If the page is pinned for DMA it will have taken a
> >> refcount on it and so the page won't be considered free/idle per
> >> dax_wait_page_idle() or any of the other mm code
Dan Williams writes:
> Alistair Popple wrote:
> [..]
>> >
>> > Was there a discussion I missed about why the conversion to typical
>> > folios allows the page->share accounting to be dropped.
>>
>> The problem with keeping it is we now treat DAX pages as "normal"
>> pages according to vm_norma
Dan Williams writes:
> Alistair Popple wrote:
[...]
>> @@ -318,85 +323,58 @@ static unsigned long dax_end_pfn(void *entry)
>> */
>> #define for_each_mapped_pfn(entry, pfn) \
>> for (pfn = dax_to_pfn(entry); \
>> -pfn < dax_end_pfn(entry); pfn++)
>> +pfn
Alistair Popple wrote:
> Currently fs dax pages are considered free when the refcount drops to
> one and their refcounts are not increased when mapped via PTEs or
> decreased when unmapped. This requires special logic in mm paths to
> detect that these pages should not be properly refcounted, and t
