Messages in this thread Patch in this message | | | Date | Tue, 9 Aug 2022 13:31:07 +0100 | From | Matthew Wilcox <> | Subject | Re: [PATCH] mm: re-allow pinning of zero pfns (again) |
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On Mon, Aug 08, 2022 at 10:42:24PM -0600, Alex Williamson wrote: > The below referenced commit makes the same error as 1c563432588d ("mm: fix > is_pinnable_page against a cma page"), re-interpreting the logic to exclude > pinning of the zero page, which breaks device assignment with vfio.
Perhaps we need to admit we're not as good at boolean logic as we think we are.
if (is_device_coherent_page(page)) return false; if (is_zone_movable_page(page)) return false; return is_zero_pfn(page_to_pfn(page));
(or whatever the right logic is ... I just woke up and I'm having trouble parsing it).
> Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen > Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support") > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > --- > include/linux/mm.h | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 18e01474cf6b..772279ed7010 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1544,9 +1544,8 @@ static inline bool is_longterm_pinnable_page(struct page *page) > if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE) > return false; > #endif > - return !(is_device_coherent_page(page) || > - is_zone_movable_page(page) || > - is_zero_pfn(page_to_pfn(page))); > + return !(is_device_coherent_page(page) || is_zone_movable_page(page)) || > + is_zero_pfn(page_to_pfn(page)); > } > #else > static inline bool is_longterm_pinnable_page(struct page *page) > > >
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