diff options
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 143 |
1 files changed, 93 insertions, 50 deletions
@@ -2273,20 +2273,57 @@ struct page *get_dump_page(unsigned long addr) #endif /* CONFIG_ELF_CORE */ #ifdef CONFIG_MIGRATION + +/* + * An array of either pages or folios ("pofs"). Although it may seem tempting to + * avoid this complication, by simply interpreting a list of folios as a list of + * pages, that approach won't work in the longer term, because eventually the + * layouts of struct page and struct folio will become completely different. + * Furthermore, this pof approach avoids excessive page_folio() calls. + */ +struct pages_or_folios { + union { + struct page **pages; + struct folio **folios; + void **entries; + }; + bool has_folios; + long nr_entries; +}; + +static struct folio *pofs_get_folio(struct pages_or_folios *pofs, long i) +{ + if (pofs->has_folios) + return pofs->folios[i]; + return page_folio(pofs->pages[i]); +} + +static void pofs_clear_entry(struct pages_or_folios *pofs, long i) +{ + pofs->entries[i] = NULL; +} + +static void pofs_unpin(struct pages_or_folios *pofs) +{ + if (pofs->has_folios) + unpin_folios(pofs->folios, pofs->nr_entries); + else + unpin_user_pages(pofs->pages, pofs->nr_entries); +} + /* * Returns the number of collected folios. Return value is always >= 0. */ static unsigned long collect_longterm_unpinnable_folios( - struct list_head *movable_folio_list, - unsigned long nr_folios, - struct folio **folios) + struct list_head *movable_folio_list, + struct pages_or_folios *pofs) { unsigned long i, collected = 0; struct folio *prev_folio = NULL; bool drain_allow = true; - for (i = 0; i < nr_folios; i++) { - struct folio *folio = folios[i]; + for (i = 0; i < pofs->nr_entries; i++) { + struct folio *folio = pofs_get_folio(pofs, i); if (folio == prev_folio) continue; @@ -2327,16 +2364,15 @@ static unsigned long collect_longterm_unpinnable_folios( * Returns -EAGAIN if all folios were successfully migrated or -errno for * failure (or partial success). */ -static int migrate_longterm_unpinnable_folios( - struct list_head *movable_folio_list, - unsigned long nr_folios, - struct folio **folios) +static int +migrate_longterm_unpinnable_folios(struct list_head *movable_folio_list, + struct pages_or_folios *pofs) { int ret; unsigned long i; - for (i = 0; i < nr_folios; i++) { - struct folio *folio = folios[i]; + for (i = 0; i < pofs->nr_entries; i++) { + struct folio *folio = pofs_get_folio(pofs, i); if (folio_is_device_coherent(folio)) { /* @@ -2344,7 +2380,7 @@ static int migrate_longterm_unpinnable_folios( * convert the pin on the source folio to a normal * reference. */ - folios[i] = NULL; + pofs_clear_entry(pofs, i); folio_get(folio); gup_put_folio(folio, 1, FOLL_PIN); @@ -2363,8 +2399,8 @@ static int migrate_longterm_unpinnable_folios( * calling folio_isolate_lru() which takes a reference so the * folio won't be freed if it's migrating. */ - unpin_folio(folios[i]); - folios[i] = NULL; + unpin_folio(folio); + pofs_clear_entry(pofs, i); } if (!list_empty(movable_folio_list)) { @@ -2387,66 +2423,73 @@ static int migrate_longterm_unpinnable_folios( return -EAGAIN; err: - unpin_folios(folios, nr_folios); + pofs_unpin(pofs); putback_movable_pages(movable_folio_list); return ret; } +static long +check_and_migrate_movable_pages_or_folios(struct pages_or_folios *pofs) +{ + LIST_HEAD(movable_folio_list); + unsigned long collected; + + collected = collect_longterm_unpinnable_folios(&movable_folio_list, + pofs); + if (!collected) + return 0; + + return migrate_longterm_unpinnable_folios(&movable_folio_list, pofs); +} + /* - * Check whether all folios are *allowed* to be pinned indefinitely (longterm). + * Check whether all folios are *allowed* to be pinned indefinitely (long term). * Rather confusingly, all folios in the range are required to be pinned via * FOLL_PIN, before calling this routine. * - * If any folios in the range are not allowed to be pinned, then this routine - * will migrate those folios away, unpin all the folios in the range and return - * -EAGAIN. The caller should re-pin the entire range with FOLL_PIN and then - * call this routine again. + * Return values: * - * If an error other than -EAGAIN occurs, this indicates a migration failure. - * The caller should give up, and propagate the error back up the call stack. - * - * If everything is OK and all folios in the range are allowed to be pinned, + * 0: if everything is OK and all folios in the range are allowed to be pinned, * then this routine leaves all folios pinned and returns zero for success. + * + * -EAGAIN: if any folios in the range are not allowed to be pinned, then this + * routine will migrate those folios away, unpin all the folios in the range. If + * migration of the entire set of folios succeeds, then -EAGAIN is returned. The + * caller should re-pin the entire range with FOLL_PIN and then call this + * routine again. + * + * -ENOMEM, or any other -errno: if an error *other* than -EAGAIN occurs, this + * indicates a migration failure. The caller should give up, and propagate the + * error back up the call stack. The caller does not need to unpin any folios in + * that case, because this routine will do the unpinning. */ static long check_and_migrate_movable_folios(unsigned long nr_folios, struct folio **folios) { - unsigned long collected; - LIST_HEAD(movable_folio_list); + struct pages_or_folios pofs = { + .folios = folios, + .has_folios = true, + .nr_entries = nr_folios, + }; - collected = collect_longterm_unpinnable_folios(&movable_folio_list, - nr_folios, folios); - if (!collected) - return 0; - - return migrate_longterm_unpinnable_folios(&movable_folio_list, - nr_folios, folios); + return check_and_migrate_movable_pages_or_folios(&pofs); } /* - * This routine just converts all the pages in the @pages array to folios and - * calls check_and_migrate_movable_folios() to do the heavy lifting. - * - * Please see the check_and_migrate_movable_folios() documentation for details. + * Return values and behavior are the same as those for + * check_and_migrate_movable_folios(). */ static long check_and_migrate_movable_pages(unsigned long nr_pages, struct page **pages) { - struct folio **folios; - long i, ret; + struct pages_or_folios pofs = { + .pages = pages, + .has_folios = false, + .nr_entries = nr_pages, + }; - folios = kmalloc_array(nr_pages, sizeof(*folios), GFP_KERNEL); - if (!folios) - return -ENOMEM; - - for (i = 0; i < nr_pages; i++) - folios[i] = page_folio(pages[i]); - - ret = check_and_migrate_movable_folios(nr_pages, folios); - - kfree(folios); - return ret; + return check_and_migrate_movable_pages_or_folios(&pofs); } #else static long check_and_migrate_movable_pages(unsigned long nr_pages, |