From patchwork Thu Jul 15 03:35:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12378449 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3B3DC47E48 for ; Thu, 15 Jul 2021 03:52:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 860A161360 for ; Thu, 15 Jul 2021 03:52:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234291AbhGODzD (ORCPT ); Wed, 14 Jul 2021 23:55:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231378AbhGODzD (ORCPT ); Wed, 14 Jul 2021 23:55:03 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05F97C06175F; Wed, 14 Jul 2021 20:52:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=yJjcL8JeT4ttM0WfFdjzDq9LTGoepY5vhGwfSSvIaTY=; b=DiLMs0A5FFEsfF4hgDykRoBmm7 taepqtiDtpuKFLEXllIuWLXq//zU4sr4XDmW8Ax+/UxRfjCTzySv65UmzausBOCeKGwGbouZS8n/z kWZupXDUO+UIOujntqsGAhDVnFtPeK7+l/jqPJHIvsQ889j4bseBCNmhhCu3IcWQf/nVhuJHXxSfJ 3isEj0IEx4+I5l7yVNfsucMFPC/2gIrVbtC5A/h7tDpXs6YmuhO2I0FfoNFViDWHAVRcO8R2X38If qJaoMXTTvDIJblIuLEvt3AuzXzrbOzJfw8rxJlmSLaEiAvmIESkPRdfsAvnVZYxFWcnT55Yha2Ppd iXBVchdA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m3sNW-002v1u-Hs; Thu, 15 Jul 2021 03:49:56 +0000 From: "Matthew Wilcox (Oracle)" To: linux-kernel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig , Jeff Layton , "Kirill A . Shutemov" , William Kucharski , David Howells Subject: [PATCH v14 017/138] mm/filemap: Add folio_unlock() Date: Thu, 15 Jul 2021 04:35:03 +0100 Message-Id: <20210715033704.692967-18-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210715033704.692967-1-willy@infradead.org> References: <20210715033704.692967-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Convert unlock_page() to call folio_unlock(). By using a folio we avoid a call to compound_head(). This shortens the function from 39 bytes to 25 and removes 4 instructions on x86-64. Because we still have unlock_page(), it's a net increase of 16 bytes of text for the kernel as a whole, but any path that uses folio_unlock() will execute 4 fewer instructions. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Acked-by: Jeff Layton Acked-by: Kirill A. Shutemov Reviewed-by: William Kucharski Reviewed-by: David Howells Acked-by: Mike Rapoport Acked-by: Vlastimil Babka --- include/linux/pagemap.h | 3 ++- mm/filemap.c | 29 ++++++++++++----------------- mm/folio-compat.c | 6 ++++++ 3 files changed, 20 insertions(+), 18 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index a0925a89ba11..a13edc7a2916 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -658,7 +658,8 @@ extern int __lock_page_killable(struct page *page); extern int __lock_page_async(struct page *page, struct wait_page_queue *wait); extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags); -extern void unlock_page(struct page *page); +void unlock_page(struct page *page); +void folio_unlock(struct folio *folio); /* * Return true if the page was successfully locked diff --git a/mm/filemap.c b/mm/filemap.c index 634adeacc4c1..1af67ef94e4c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1435,29 +1435,24 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem #endif /** - * unlock_page - unlock a locked page - * @page: the page + * folio_unlock - Unlock a locked folio. + * @folio: The folio. * - * Unlocks the page and wakes up sleepers in wait_on_page_locked(). - * Also wakes sleepers in wait_on_page_writeback() because the wakeup - * mechanism between PageLocked pages and PageWriteback pages is shared. - * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep. + * Unlocks the folio and wakes up any thread sleeping on the page lock. * - * Note that this depends on PG_waiters being the sign bit in the byte - * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to - * clear the PG_locked bit and test PG_waiters at the same time fairly - * portably (architectures that do LL/SC can test any bit, while x86 can - * test the sign bit). + * Context: May be called from interrupt or process context. May not be + * called from NMI context. */ -void unlock_page(struct page *page) +void folio_unlock(struct folio *folio) { + /* Bit 7 allows x86 to check the byte's sign bit */ BUILD_BUG_ON(PG_waiters != 7); - page = compound_head(page); - VM_BUG_ON_PAGE(!PageLocked(page), page); - if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags)) - wake_up_page_bit(page, PG_locked); + BUILD_BUG_ON(PG_locked > 7); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0))) + wake_up_page_bit(&folio->page, PG_locked); } -EXPORT_SYMBOL(unlock_page); +EXPORT_SYMBOL(folio_unlock); /** * end_page_private_2 - Clear PG_private_2 and release any waiters diff --git a/mm/folio-compat.c b/mm/folio-compat.c index 5e107aa30a62..91b3d00a92f7 100644 --- a/mm/folio-compat.c +++ b/mm/folio-compat.c @@ -11,3 +11,9 @@ struct address_space *page_mapping(struct page *page) return folio_mapping(page_folio(page)); } EXPORT_SYMBOL(page_mapping); + +void unlock_page(struct page *page) +{ + return folio_unlock(page_folio(page)); +} +EXPORT_SYMBOL(unlock_page);