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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rbAOi-00000006HD7-1LGF; Sat, 17 Feb 2024 02:25:48 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org Subject: [PATCH v2 01/18] mm: Make folios_put() the basis of release_pages() Date: Sat, 17 Feb 2024 02:25:27 +0000 Message-ID: <20240217022546.1496101-2-willy@infradead.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240217022546.1496101-1-willy@infradead.org> References: <20240217022546.1496101-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 7BD5DA0012 X-Stat-Signature: pnem49453efa4iwzg8thqbno57wd9g9y X-HE-Tag: 1708136759-654469 X-HE-Meta: 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 OU/8tzp9 ShubFYQ7FcDsLEtsxMJLVAo/7VUf09UFumpBys6uIS6sqOve9oyW6kb8PD1kaiXz5HYQBYl+a8LhvU5i5cbzUN37pKthemXaVoQSLcVefo+XAe8B1Vl2ZsOdOppMUziqha1SeL+73+CxyH35efCEbz05xXD9fvlGlnIf+ywD9fCl/koPwOmX7KF10YJJcSm0lMgdHkVAP7gupFP6Ebb42dnkgx41xduy9JL2Q X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: By making release_pages() call folios_put(), we can get rid of the calls to compound_head() for the callers that already know they have folios. We can also get rid of the lock_batch tracking as we know the size of the batch is limited by folio_batch. This does reduce the maximum number of pages for which the lruvec lock is held, from SWAP_CLUSTER_MAX (32) to PAGEVEC_SIZE (15). I do not expect this to make a significant difference, but if it does, we can increase PAGEVEC_SIZE to 31. Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/mm.h | 19 ++--------- mm/mlock.c | 3 +- mm/swap.c | 84 +++++++++++++++++++++++++++------------------- 3 files changed, 52 insertions(+), 54 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 6095c86aa040..2a1ebda5fb79 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -36,6 +36,7 @@ struct anon_vma; struct anon_vma_chain; struct user_struct; struct pt_regs; +struct folio_batch; extern int sysctl_page_lock_unfairness; @@ -1532,23 +1533,7 @@ typedef union { } release_pages_arg __attribute__ ((__transparent_union__)); void release_pages(release_pages_arg, int nr); - -/** - * folios_put - Decrement the reference count on an array of folios. - * @folios: The folios. - * @nr: How many folios there are. - * - * Like folio_put(), but for an array of folios. This is more efficient - * than writing the loop yourself as it will optimise the locks which - * need to be taken if the folios are freed. - * - * Context: May be called in process or interrupt context, but not in NMI - * context. May be called while holding a spinlock. - */ -static inline void folios_put(struct folio **folios, unsigned int nr) -{ - release_pages(folios, nr); -} +void folios_put(struct folio_batch *folios); static inline void put_page(struct page *page) { diff --git a/mm/mlock.c b/mm/mlock.c index 086546ac5766..1ed2f2ab37cd 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -206,8 +206,7 @@ static void mlock_folio_batch(struct folio_batch *fbatch) if (lruvec) unlock_page_lruvec_irq(lruvec); - folios_put(fbatch->folios, folio_batch_count(fbatch)); - folio_batch_reinit(fbatch); + folios_put(fbatch); } void mlock_drain_local(void) diff --git a/mm/swap.c b/mm/swap.c index cd8f0150ba3a..7bdc63b56859 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -89,7 +89,7 @@ static void __page_cache_release(struct folio *folio) __folio_clear_lru_flags(folio); unlock_page_lruvec_irqrestore(lruvec, flags); } - /* See comment on folio_test_mlocked in release_pages() */ + /* See comment on folio_test_mlocked in folios_put() */ if (unlikely(folio_test_mlocked(folio))) { long nr_pages = folio_nr_pages(folio); @@ -175,7 +175,7 @@ static void lru_add_fn(struct lruvec *lruvec, struct folio *folio) * while the LRU lock is held. * * (That is not true of __page_cache_release(), and not necessarily - * true of release_pages(): but those only clear the mlocked flag after + * true of folios_put(): but those only clear the mlocked flag after * folio_put_testzero() has excluded any other users of the folio.) */ if (folio_evictable(folio)) { @@ -221,8 +221,7 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) if (lruvec) unlock_page_lruvec_irqrestore(lruvec, flags); - folios_put(fbatch->folios, folio_batch_count(fbatch)); - folio_batch_reinit(fbatch); + folios_put(fbatch); } static void folio_batch_add_and_move(struct folio_batch *fbatch, @@ -946,41 +945,27 @@ void lru_cache_disable(void) } /** - * release_pages - batched put_page() - * @arg: array of pages to release - * @nr: number of pages + * folios_put - Decrement the reference count on a batch of folios. + * @folios: The folios. * - * Decrement the reference count on all the pages in @arg. If it - * fell to zero, remove the page from the LRU and free it. + * Like folio_put(), but for a batch of folios. This is more efficient + * than writing the loop yourself as it will optimise the locks which need + * to be taken if the folios are freed. The folios batch is returned + * empty and ready to be reused for another batch; there is no need to + * reinitialise it. * - * Note that the argument can be an array of pages, encoded pages, - * or folio pointers. We ignore any encoded bits, and turn any of - * them into just a folio that gets free'd. + * Context: May be called in process or interrupt context, but not in NMI + * context. May be called while holding a spinlock. */ -void release_pages(release_pages_arg arg, int nr) +void folios_put(struct folio_batch *folios) { int i; - struct encoded_page **encoded = arg.encoded_pages; LIST_HEAD(pages_to_free); struct lruvec *lruvec = NULL; unsigned long flags = 0; - unsigned int lock_batch; - for (i = 0; i < nr; i++) { - struct folio *folio; - - /* Turn any of the argument types into a folio */ - folio = page_folio(encoded_page_ptr(encoded[i])); - - /* - * Make sure the IRQ-safe lock-holding time does not get - * excessive with a continuous string of pages from the - * same lruvec. The lock is held only if lruvec != NULL. - */ - if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) { - unlock_page_lruvec_irqrestore(lruvec, flags); - lruvec = NULL; - } + for (i = 0; i < folios->nr; i++) { + struct folio *folio = folios->folios[i]; if (is_huge_zero_page(&folio->page)) continue; @@ -1010,13 +995,8 @@ void release_pages(release_pages_arg arg, int nr) } if (folio_test_lru(folio)) { - struct lruvec *prev_lruvec = lruvec; - lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); - if (prev_lruvec != lruvec) - lock_batch = 0; - lruvec_del_folio(lruvec, folio); __folio_clear_lru_flags(folio); } @@ -1040,6 +1020,40 @@ void release_pages(release_pages_arg arg, int nr) mem_cgroup_uncharge_list(&pages_to_free); free_unref_page_list(&pages_to_free); + folios->nr = 0; +} +EXPORT_SYMBOL(folios_put); + +/** + * release_pages - batched put_page() + * @arg: array of pages to release + * @nr: number of pages + * + * Decrement the reference count on all the pages in @arg. If it + * fell to zero, remove the page from the LRU and free it. + * + * Note that the argument can be an array of pages, encoded pages, + * or folio pointers. We ignore any encoded bits, and turn any of + * them into just a folio that gets free'd. + */ +void release_pages(release_pages_arg arg, int nr) +{ + struct folio_batch fbatch; + struct encoded_page **encoded = arg.encoded_pages; + int i; + + folio_batch_init(&fbatch); + for (i = 0; i < nr; i++) { + /* Turn any of the argument types into a folio */ + struct folio *folio = page_folio(encoded_page_ptr(encoded[i])); + + if (folio_batch_add(&fbatch, folio) > 0) + continue; + folios_put(&fbatch); + } + + if (fbatch.nr) + folios_put(&fbatch); } EXPORT_SYMBOL(release_pages); -- 2.43.0