folio_fast_pin_allowed() does not support ZONE_DEVICE pages because currently it is impossible for that type of page to be used with FOLL_LONGTERM. When this changes in a subsequent patch, this path will attempt to read the mapping of a ZONE_DEVICE page which is not valid. Instead, allow ZONE_DEVICE pages explicitly seeing they shouldn't pose any problem with the fast path. Co-developed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> Signed-off-by: Martin Oliveira <martin.oliveira@xxxxxxxxxxxxx> --- mm/gup.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index ca0f5cedce9b2..00d0a77112f4f 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2847,6 +2847,10 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) if (folio_test_hugetlb(folio)) return true; + /* It makes no sense to access the mapping of ZONE_DEVICE pages */ + if (folio_is_zone_device(folio)) + return true; + /* * GUP-fast disables IRQs. When IRQS are disabled, RCU grace periods * cannot proceed, which means no actions performed under RCU can -- 2.43.0
