diff options
| -rw-r--r-- | mm/gup.c | 99 | ||||
| -rw-r--r-- | mm/internal.h | 5 |
2 files changed, 54 insertions, 50 deletions
@@ -47,75 +47,70 @@ static void put_page_refs(struct page *page, int refs) } /* - * Return the compound head page with ref appropriately incremented, + * Return the folio with ref appropriately incremented, * or NULL if that failed. */ -static inline struct page *try_get_compound_head(struct page *page, int refs) +static inline struct folio *try_get_folio(struct page *page, int refs) { - struct page *head; + struct folio *folio; retry: - head = compound_head(page); - - if (WARN_ON_ONCE(page_ref_count(head) < 0)) + folio = page_folio(page); + if (WARN_ON_ONCE(folio_ref_count(folio) < 0)) return NULL; - if (unlikely(!page_cache_add_speculative(head, refs))) + if (unlikely(!folio_ref_try_add_rcu(folio, refs))) return NULL; /* - * At this point we have a stable reference to the head page; but it - * could be that between the compound_head() lookup and the refcount - * increment, the compound page was split, in which case we'd end up - * holding a reference on a page that has nothing to do with the page + * At this point we have a stable reference to the folio; but it + * could be that between calling page_folio() and the refcount + * increment, the folio was split, in which case we'd end up + * holding a reference on a folio that has nothing to do with the page * we were given anymore. - * So now that the head page is stable, recheck that the pages still - * belong together. + * So now that the folio is stable, recheck that the page still + * belongs to this folio. */ - if (unlikely(compound_head(page) != head)) { - put_page_refs(head, refs); + if (unlikely(page_folio(page) != folio)) { + folio_put_refs(folio, refs); goto retry; } - return head; + return folio; } /** - * try_grab_compound_head() - attempt to elevate a page's refcount, by a - * flags-dependent amount. - * - * Even though the name includes "compound_head", this function is still - * appropriate for callers that have a non-compound @page to get. - * + * try_grab_folio() - Attempt to get or pin a folio. * @page: pointer to page to be grabbed - * @refs: the value to (effectively) add to the page's refcount + * @refs: the value to (effectively) add to the folio's refcount * @flags: gup flags: these are the FOLL_* flag values. * * "grab" names in this file mean, "look at flags to decide whether to use - * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount. + * FOLL_PIN or FOLL_GET behavior, when incrementing the folio's refcount. * * Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the * same time. (That's true throughout the get_user_pages*() and * pin_user_pages*() APIs.) Cases: * - * FOLL_GET: page's refcount will be incremented by @refs. + * FOLL_GET: folio's refcount will be incremented by @refs. * - * FOLL_PIN on compound pages: page's refcount will be incremented by - * @refs, and page[1].compound_pincount will be incremented by @refs. + * FOLL_PIN on large folios: folio's refcount will be incremented by + * @refs, and its compound_pincount will be incremented by @refs. * - * FOLL_PIN on normal pages: page's refcount will be incremented by + * FOLL_PIN on single-page folios: folio's refcount will be incremented by * @refs * GUP_PIN_COUNTING_BIAS. * - * Return: head page (with refcount appropriately incremented) for success, or - * NULL upon failure. If neither FOLL_GET nor FOLL_PIN was set, that's - * considered failure, and furthermore, a likely bug in the caller, so a warning - * is also emitted. + * Return: The folio containing @page (with refcount appropriately + * incremented) for success, or NULL upon failure. If neither FOLL_GET + * nor FOLL_PIN was set, that's considered failure, and furthermore, + * a likely bug in the caller, so a warning is also emitted. */ -__maybe_unused struct page *try_grab_compound_head(struct page *page, - int refs, unsigned int flags) +struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags) { if (flags & FOLL_GET) - return try_get_compound_head(page, refs); + return try_get_folio(page, refs); else if (flags & FOLL_PIN) { + struct folio *folio; + /* * Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a * right zone, so fail and let the caller fall back to the slow @@ -129,34 +124,38 @@ __maybe_unused struct page *try_grab_compound_head(struct page *page, * CAUTION: Don't use compound_head() on the page before this * point, the result won't be stable. */ - page = try_get_compound_head(page, refs); - if (!page) + folio = try_get_folio(page, refs); + if (!folio) return NULL; /* - * When pinning a compound page, use an exact count to - * track it. + * When pinning a large folio, use an exact count to track it. * - * However, be sure to *also* increment the normal page - * refcount field at least once, so that the page really + * However, be sure to *also* increment the normal folio + * refcount field at least once, so that the folio really * is pinned. That's why the refcount from the earlier - * try_get_compound_head() is left intact. + * try_get_folio() is left intact. */ - if (PageHead(page)) - atomic_add(refs, compound_pincount_ptr(page)); + if (folio_test_large(folio)) + atomic_add(refs, folio_pincount_ptr(folio)); else - page_ref_add(page, refs * (GUP_PIN_COUNTING_BIAS - 1)); + folio_ref_add(folio, + refs * (GUP_PIN_COUNTING_BIAS - 1)); + node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, refs); - mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, - refs); - - return page; + return folio; } WARN_ON_ONCE(1); return NULL; } +struct page *try_grab_compound_head(struct page *page, + int refs, unsigned int flags) +{ + return &try_grab_folio(page, refs, flags)->page; +} + static void put_compound_head(struct page *page, int refs, unsigned int flags) { VM_BUG_ON_PAGE(PageTail(page), page); @@ -185,7 +184,7 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags) * @flags: gup flags: these are the FOLL_* flag values. * * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same - * time. Cases: please see the try_grab_compound_head() documentation, with + * time. Cases: please see the try_grab_folio() documentation, with * "refs=1". * * Return: true for success, or if no action was required (if neither FOLL_PIN diff --git a/mm/internal.h b/mm/internal.h index 3756dd5d2c92..98b97cb5a97b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -737,4 +737,9 @@ int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, void free_zone_device_page(struct page *page); +/* + * mm/gup.c + */ +struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags); + #endif /* __MM_INTERNAL_H */ |