On Tue, 30 May 2023 09:42:33 -0600 Khalid Aziz <khalid.aziz@xxxxxxxxxx> wrote:
I completely agree that we should be careful with such mapcount vs. pagecount checks, and if we can use something
better, let's use something *better*.
When we have a reliable folio_maybe_dma_longterm_pinned() function, it will be better to call that instead of doing
refcount vs mapcount check. Until that better function to check for pinned pages is in place, may I propose that the
current patch fixes a customer problem though not optimally and is a good enough working solution. When a better
function is in place, page_has_extra_refs() function can be updated to rely on this other function instead of refcount
vs mapcount.
We seem rather stuck with this patch. I think I'll drop it while we
ponder a way forward.