diff options
Diffstat (limited to 'mm/memfd.c')
| -rw-r--r-- | mm/memfd.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/mm/memfd.c b/mm/memfd.c index 7d8d3ab3fa37..e7b7c5294d59 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -60,6 +60,51 @@ static void memfd_tag_pins(struct xa_state *xas) } /* + * This is a helper function used by memfd_pin_user_pages() in GUP (gup.c). + * It is mainly called to allocate a folio in a memfd when the caller + * (memfd_pin_folios()) cannot find a folio in the page cache at a given + * index in the mapping. + */ +struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx) +{ +#ifdef CONFIG_HUGETLB_PAGE + struct folio *folio; + gfp_t gfp_mask; + int err; + + if (is_file_hugepages(memfd)) { + /* + * The folio would most likely be accessed by a DMA driver, + * therefore, we have zone memory constraints where we can + * alloc from. Also, the folio will be pinned for an indefinite + * amount of time, so it is not expected to be migrated away. + */ + gfp_mask = htlb_alloc_mask(hstate_file(memfd)); + gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE); + + folio = alloc_hugetlb_folio_nodemask(hstate_file(memfd), + numa_node_id(), + NULL, + gfp_mask, + false); + if (folio && folio_try_get(folio)) { + err = hugetlb_add_to_page_cache(folio, + memfd->f_mapping, + idx); + if (err) { + folio_put(folio); + free_huge_folio(folio); + return ERR_PTR(err); + } + return folio; + } + return ERR_PTR(-ENOMEM); + } +#endif + return shmem_read_folio(memfd->f_mapping, idx); +} + +/* * Setting SEAL_WRITE requires us to verify there's no pending writer. However, * via get_user_pages(), drivers might have some pending I/O without any active * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all folios |