On Tue, 5 Jul 2022 20:35:32 +0800 Muchun Song <songmuc...@bytedance.com> wrote:
> FSDAX page refcounts are 1-based, rather than 0-based: if refcount is > 1, then the page is freed. The FSDAX pages can be pinned through GUP, > then they will be unpinned via unpin_user_page() using a folio variant > to put the page, however, folio variants did not consider this special > case, the result will be to miss a wakeup event (like the user of > __fuse_dax_break_layouts()). Since FSDAX pages are only possible get > by GUP users, so fix GUP instead of folio_put() to lower overhead. > What are the user visible runtime effects of this bug?
