From patchwork Wed Aug 30 09:50:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370143 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8502C6FA8F for ; Wed, 30 Aug 2023 09:50:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 357368E0009; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B76828004E; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 109468E004E; Wed, 30 Aug 2023 05:50:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0054E8E0009 for ; Wed, 30 Aug 2023 05:50:33 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id B7BB0A028B for ; Wed, 30 Aug 2023 09:50:33 +0000 (UTC) X-FDA: 81180301146.04.47E5E35 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf07.hostedemail.com (Postfix) with ESMTP id 119334000C for ; Wed, 30 Aug 2023 09:50:31 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389032; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rg768vUtzYQIWfRK/vocg9s9AsOKLD8pS52LGJ1MyoA=; b=CEHS0TRVo0H0x8kIAMo+xUY1pb3/HaZuKCryXMZzT0GM16Z2ZyxQt2tOR0EQM2zrlQhfSX S0FsZpRW6lNFxtfUT1cSnwzptQqZmo49VQTQShY6eKQkFiF6/oFgnr9W+/HbTA5Pev3mjh zQV+V+pv5J2dpmm3Ctjr0Z6T7vGx+RY= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389032; a=rsa-sha256; cv=none; b=K4x9IryTndIXwXeXQkJWpJRn2VAz1eMOUAKsmih1HMwcSlaOaFAcYooPg57zrOy0tCWMvZ Q7uwcw9Bvj0T//NhlK3zXt9+jDiN/iAp2T6aCxF+VHsXmt5eDQn+GCGtpfqJ+BBQjzOJ5/ HxaNLiGbRmTbnWJeR6IvIfpocljs8hY= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9D1C1FEC; Wed, 30 Aug 2023 02:51:10 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9E2F23F64C; Wed, 30 Aug 2023 02:50:28 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/5] mm: Implement folio_remove_rmap_range() Date: Wed, 30 Aug 2023 10:50:07 +0100 Message-Id: <20230830095011.1228673-2-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 119334000C X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ahehe69ha9xw9s9xgu6afopgz6n8wo38 X-HE-Tag: 1693389031-364789 X-HE-Meta: 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 vFYZ0W1Q GkLv9kDyRfb6kIYHDwOaFbnPYaikXk2p6QOTCCVfNjluqUM7s83M70BB/yOUNyBy/hle6U3gpYvMkfCKNv7agBWg1EVKhtsRG+sSd1/XTYlDJrUEs1FMaJvWT5c85/v10nvBkv0Dh1PTibASRUErgjvBfJ+oTdobPjM4M5hiaRbIFhjQL4706eH6eE+j5tHQmuKAgxmEfs0UMxiQ= 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: Like page_remove_rmap() but batch-removes the rmap for a range of pages belonging to a folio. This can provide a small speedup due to less manipuation of the various counters. But more crucially, if removing the rmap for all pages of a folio in a batch, there is no need to (spuriously) add it to the deferred split list, which saves significant cost when there is contention for the split queue lock. All contained pages are accounted using the order-0 folio (or base page) scheme. page_remove_rmap() is refactored so that it forwards to folio_remove_rmap_range() for !compound cases, and both functions now share a common epilogue function. The intention here is to avoid duplication of code. Signed-off-by: Ryan Roberts --- include/linux/rmap.h | 2 + mm/rmap.c | 125 ++++++++++++++++++++++++++++++++----------- 2 files changed, 97 insertions(+), 30 deletions(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 51cc21ebb568..f2e5af3c0e7f 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -202,6 +202,8 @@ void folio_add_file_rmap_range(struct folio *, struct page *, unsigned int nr, struct vm_area_struct *, bool compound); void page_remove_rmap(struct page *, struct vm_area_struct *, bool compound); +void folio_remove_rmap_range(struct folio *folio, struct page *page, + int nr, struct vm_area_struct *vma); void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long address, rmap_t flags); diff --git a/mm/rmap.c b/mm/rmap.c index ec7f8e6c9e48..5ea51c70ecd6 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1379,6 +1379,94 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, folio_add_file_rmap_range(folio, page, nr_pages, vma, compound); } +/** + * __remove_rmap_finish - common operations when taking down a mapping. + * @folio: Folio containing all pages taken down. + * @vma: The VM area containing the range. + * @compound: True if pages were taken down from PMD or false if from PTE(s). + * @nr_unmapped: Number of pages within folio that are now unmapped. + * @nr_mapped: Number of pages within folio that are still mapped. + */ +static void __remove_rmap_finish(struct folio *folio, + struct vm_area_struct *vma, bool compound, + int nr_unmapped, int nr_mapped) +{ + enum node_stat_item idx; + + if (nr_unmapped) { + idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; + __lruvec_stat_mod_folio(folio, idx, -nr_unmapped); + + /* + * Queue large anon folio for deferred split if at least one + * page of the folio is unmapped and at least one page is still + * mapped. + */ + if (folio_test_large(folio) && + folio_test_anon(folio) && nr_mapped) + deferred_split_folio(folio); + } + + /* + * It would be tidy to reset folio_test_anon mapping when fully + * unmapped, but that might overwrite a racing page_add_anon_rmap + * which increments mapcount after us but sets mapping before us: + * so leave the reset to free_pages_prepare, and remember that + * it's only reliable while mapped. + */ + + munlock_vma_folio(folio, vma, compound); +} + +/** + * folio_remove_rmap_range - Take down PTE mappings from a range of pages. + * @folio: Folio containing all pages in range. + * @page: First page in range to unmap. + * @nr: Number of pages to unmap. + * @vma: The VM area containing the range. + * + * All pages in the range must belong to the same VMA & folio. They must be + * mapped with PTEs, not a PMD. + * + * Context: Caller holds the pte lock. + */ +void folio_remove_rmap_range(struct folio *folio, struct page *page, + int nr, struct vm_area_struct *vma) +{ + atomic_t *mapped = &folio->_nr_pages_mapped; + int nr_unmapped = 0; + int nr_mapped = 0; + bool last; + + if (unlikely(folio_test_hugetlb(folio))) { + VM_WARN_ON_FOLIO(1, folio); + return; + } + + VM_WARN_ON_ONCE(page < &folio->page || + page + nr > (&folio->page + folio_nr_pages(folio))); + + if (!folio_test_large(folio)) { + /* Is this the page's last map to be removed? */ + last = atomic_add_negative(-1, &page->_mapcount); + nr_unmapped = last; + } else { + for (; nr != 0; nr--, page++) { + /* Is this the page's last map to be removed? */ + last = atomic_add_negative(-1, &page->_mapcount); + if (last) + nr_unmapped++; + } + + /* Pages still mapped if folio mapped entirely */ + nr_mapped = atomic_sub_return_relaxed(nr_unmapped, mapped); + if (nr_mapped >= COMPOUND_MAPPED) + nr_unmapped = 0; + } + + __remove_rmap_finish(folio, vma, false, nr_unmapped, nr_mapped); +} + /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from @@ -1405,15 +1493,13 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, return; } - /* Is page being unmapped by PTE? Is this its last map to be removed? */ + /* Is page being unmapped by PTE? */ if (likely(!compound)) { - last = atomic_add_negative(-1, &page->_mapcount); - nr = last; - if (last && folio_test_large(folio)) { - nr = atomic_dec_return_relaxed(mapped); - nr = (nr < COMPOUND_MAPPED); - } - } else if (folio_test_pmd_mappable(folio)) { + folio_remove_rmap_range(folio, page, 1, vma); + return; + } + + if (folio_test_pmd_mappable(folio)) { /* That test is redundant: it's for safety or to optimize out */ last = atomic_add_negative(-1, &folio->_entire_mapcount); @@ -1441,29 +1527,8 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma, idx = NR_FILE_PMDMAPPED; __lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped); } - if (nr) { - idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; - __lruvec_stat_mod_folio(folio, idx, -nr); - - /* - * Queue anon THP for deferred split if at least one - * page of the folio is unmapped and at least one page - * is still mapped. - */ - if (folio_test_pmd_mappable(folio) && folio_test_anon(folio)) - if (!compound || nr < nr_pmdmapped) - deferred_split_folio(folio); - } - - /* - * It would be tidy to reset folio_test_anon mapping when fully - * unmapped, but that might overwrite a racing page_add_anon_rmap - * which increments mapcount after us but sets mapping before us: - * so leave the reset to free_pages_prepare, and remember that - * it's only reliable while mapped. - */ - munlock_vma_folio(folio, vma, compound); + __remove_rmap_finish(folio, vma, compound, nr, nr_pmdmapped - nr); } /* From patchwork Wed Aug 30 09:50:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370144 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0684C83F15 for ; Wed, 30 Aug 2023 09:50:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 37BE928004F; Wed, 30 Aug 2023 05:50:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 304D828004E; Wed, 30 Aug 2023 05:50:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17E9428004F; Wed, 30 Aug 2023 05:50:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 028E028004E for ; Wed, 30 Aug 2023 05:50:37 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id D0916A0378 for ; Wed, 30 Aug 2023 09:50:36 +0000 (UTC) X-FDA: 81180301272.15.EF64D4F Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf10.hostedemail.com (Postfix) with ESMTP id 35DE2C0019 for ; Wed, 30 Aug 2023 09:50:35 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf10.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389035; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=S9VCZWuSZ6aTd42QL1q/rOhq2pSewtGN3EMk2R8LAHk=; b=RBAjO7L5WDz/btwbTOYdOmt5CDFR9psCIOcFTNAa0Rb2+FrEBBIWIH7eUo00FP/qhzww5D WTB2O3iqAKnpE7BxGudozpW/sbRkL0h1SntW8qXTRMNEOaCZeRuoKmwVprwbJYFtI4M2wl zOu2jZRGmI8noMinV+f/ssrTp7CJiSs= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf10.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389035; a=rsa-sha256; cv=none; b=pq2cYpo+mjigG/yYurIiU9qqtbjUYFoiL98fopURIRIPUdYefQxakTP00ZLwfrNN3cGSvr kQdfSuE6ZZvkmKhfZkjC6cmCS2WDswglJKMTigpILDpG74oJguNj3ySXJs8kTY6Qpqjiw9 kVkt6MLRxeO80JH/Uh+EzBAECTFTHc8= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8F9451424; Wed, 30 Aug 2023 02:51:13 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 732523F64C; Wed, 30 Aug 2023 02:50:31 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/5] mm/mmu_gather: generalize mmu_gather rmap removal mechanism Date: Wed, 30 Aug 2023 10:50:08 +0100 Message-Id: <20230830095011.1228673-3-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 35DE2C0019 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: zzozroyjtr8r7hie4txui6ahxosukyfh X-HE-Tag: 1693389035-178369 X-HE-Meta: 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 LcMt9XfO AHskV9I0hqxTI9t6zobHCIVpfLciwL3bKlm8O2Sf0XuA13Bk3uloBwWzQe5BaKfN+YIwKlrjQqKjP1Rkulj8ASNi5ONXLXJyXi4aLHi0zjkfieW3aNBOvauq8UmX35OjBz8CvSS47SMPPpi9pdJc1GCjgSAhllvtgEtdBNaX+LorgmvP8iHq91+SKO5kdtAWbi6wY0z6ZoLm6t58= 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: Commit 5df397dec7c4 ("mm: delay page_remove_rmap() until after the TLB has been flushed") added a mechanism whereby pages added to the mmu_gather buffer could indicate whether they should also be removed from the rmap. Then a call to the new tlb_flush_rmaps() API would iterate though the buffer and remove each flagged page from the rmap. This mechanism was intended for use with !PageAnon(page) pages only. Let's generalize this rmap removal mechanism so that any type of page can be removed from the rmap. This is done as preparation for batching rmap removals with folio_remove_rmap_range(), whereby we will pass a contiguous range of pages belonging to the same folio to be removed in one shot for a performance improvement. The mmu_gather now maintains a "pointer" that points to batch and index within that batch of the next page in the queue that is yet to be removed from the rmap. tlb_discard_rmaps() resets this "pointer" to the first empty location in the queue. Whenever tlb_flush_rmaps() is called, every page from "pointer" to the end of the queue is removed from the rmap. Once the mmu is flushed (tlb_flush_mmu()/tlb_finish_mmu()) any pending rmap removals are discarded. This pointer mechanism ensures that tlb_flush_rmaps() only has to walk the part of the queue for which rmap removal is pending, avoids the (potentially large) early portion of the queue for which rmap removal has already been performed but for which tlb invalidation/page freeing is still pending. tlb_flush_rmaps() must always be called under the same PTL as was used to clear the corresponding PTEs. So in practice rmap removal will be done in a batch for each PTE table, while the tlbi/freeing can continue to be done in much bigger batches outside the PTL. See this example flow: tlb_gather_mmu() for each pte table { with ptl held { for each pte { tlb_remove_tlb_entry() __tlb_remove_page() } if (any removed pages require rmap after tlbi) tlb_flush_mmu_tlbonly() tlb_flush_rmaps() } if (full) tlb_flush_mmu() } tlb_finish_mmu() So this more general mechanism is no longer just for delaying rmap removal until after tlbi, but can be used that way when required. Note that s390 does not gather pages, but does immediate tlbi and page freeing. In this case we continue to do the rmap removal page-by-page without gathering them in the mmu_gather. Signed-off-by: Ryan Roberts --- include/asm-generic/tlb.h | 34 ++++++++++++------------ mm/memory.c | 24 ++++++++++------- mm/mmu_gather.c | 54 +++++++++++++++++++++++---------------- 3 files changed, 65 insertions(+), 47 deletions(-) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 129a3a759976..f339d68cf44f 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -266,25 +266,30 @@ extern bool __tlb_remove_page_size(struct mmu_gather *tlb, #ifdef CONFIG_SMP /* - * This both sets 'delayed_rmap', and returns true. It would be an inline - * function, except we define it before the 'struct mmu_gather'. + * For configurations that support batching the rmap removal, the removal is + * triggered by calling tlb_flush_rmaps(), which must be called after the pte(s) + * are cleared and the page has been added to the mmu_gather, and before the ptl + * lock that was held for clearing the pte is released. */ -#define tlb_delay_rmap(tlb) (((tlb)->delayed_rmap = 1), true) +#define tlb_batch_rmap(tlb) (true) extern void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma); +extern void tlb_discard_rmaps(struct mmu_gather *tlb); #endif #endif /* - * We have a no-op version of the rmap removal that doesn't - * delay anything. That is used on S390, which flushes remote - * TLBs synchronously, and on UP, which doesn't have any - * remote TLBs to flush and is not preemptible due to this - * all happening under the page table lock. + * We have a no-op version of the rmap removal that doesn't do anything. That is + * used on S390, which flushes remote TLBs synchronously, and on UP, which + * doesn't have any remote TLBs to flush and is not preemptible due to this all + * happening under the page table lock. Here, the caller must manage each rmap + * removal separately. */ -#ifndef tlb_delay_rmap -#define tlb_delay_rmap(tlb) (false) -static inline void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma) { } +#ifndef tlb_batch_rmap +#define tlb_batch_rmap(tlb) (false) +static inline void tlb_flush_rmaps(struct mmu_gather *tlb, + struct vm_area_struct *vma) { } +static inline void tlb_discard_rmaps(struct mmu_gather *tlb) { } #endif /* @@ -317,11 +322,6 @@ struct mmu_gather { */ unsigned int freed_tables : 1; - /* - * Do we have pending delayed rmap removals? - */ - unsigned int delayed_rmap : 1; - /* * at which levels have we cleared entries? */ @@ -343,6 +343,8 @@ struct mmu_gather { struct mmu_gather_batch *active; struct mmu_gather_batch local; struct page *__pages[MMU_GATHER_BUNDLE]; + struct mmu_gather_batch *rmap_pend; + unsigned int rmap_pend_first; #ifdef CONFIG_MMU_GATHER_PAGE_SIZE unsigned int page_size; diff --git a/mm/memory.c b/mm/memory.c index 12647d139a13..823c8a6813d1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1405,6 +1405,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, swp_entry_t entry; tlb_change_page_size(tlb, PAGE_SIZE); + tlb_discard_rmaps(tlb); init_rss_vec(rss); start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl); if (!pte) @@ -1423,7 +1424,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, break; if (pte_present(ptent)) { - unsigned int delay_rmap; + unsigned int batch_rmap; page = vm_normal_page(vma, addr, ptent); if (unlikely(!should_zap_page(details, page))) @@ -1438,12 +1439,15 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, continue; } - delay_rmap = 0; + batch_rmap = tlb_batch_rmap(tlb); if (!PageAnon(page)) { if (pte_dirty(ptent)) { set_page_dirty(page); - if (tlb_delay_rmap(tlb)) { - delay_rmap = 1; + if (batch_rmap) { + /* + * Ensure tlb flush happens + * before rmap remove. + */ force_flush = 1; } } @@ -1451,12 +1455,12 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, mark_page_accessed(page); } rss[mm_counter(page)]--; - if (!delay_rmap) { + if (!batch_rmap) { page_remove_rmap(page, vma, false); if (unlikely(page_mapcount(page) < 0)) print_bad_pte(vma, addr, ptent, page); } - if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) { + if (unlikely(__tlb_remove_page(tlb, page, 0))) { force_flush = 1; addr += PAGE_SIZE; break; @@ -1517,10 +1521,12 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, arch_leave_lazy_mmu_mode(); /* Do the actual TLB flush before dropping ptl */ - if (force_flush) { + if (force_flush) tlb_flush_mmu_tlbonly(tlb); - tlb_flush_rmaps(tlb, vma); - } + + /* Rmap removal must always happen before dropping ptl */ + tlb_flush_rmaps(tlb, vma); + pte_unmap_unlock(start_pte, ptl); /* diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c index 4f559f4ddd21..fb34151c0da9 100644 --- a/mm/mmu_gather.c +++ b/mm/mmu_gather.c @@ -19,10 +19,6 @@ static bool tlb_next_batch(struct mmu_gather *tlb) { struct mmu_gather_batch *batch; - /* Limit batching if we have delayed rmaps pending */ - if (tlb->delayed_rmap && tlb->active != &tlb->local) - return false; - batch = tlb->active; if (batch->next) { tlb->active = batch->next; @@ -48,37 +44,49 @@ static bool tlb_next_batch(struct mmu_gather *tlb) } #ifdef CONFIG_SMP -static void tlb_flush_rmap_batch(struct mmu_gather_batch *batch, struct vm_area_struct *vma) +static void tlb_flush_rmap_batch(struct mmu_gather_batch *batch, + unsigned int first, + struct vm_area_struct *vma) { - for (int i = 0; i < batch->nr; i++) { + for (int i = first; i < batch->nr; i++) { struct encoded_page *enc = batch->encoded_pages[i]; + struct page *page = encoded_page_ptr(enc); - if (encoded_page_flags(enc)) { - struct page *page = encoded_page_ptr(enc); - page_remove_rmap(page, vma, false); - } + page_remove_rmap(page, vma, false); } } /** - * tlb_flush_rmaps - do pending rmap removals after we have flushed the TLB + * tlb_flush_rmaps - do pending rmap removals * @tlb: the current mmu_gather * @vma: The memory area from which the pages are being removed. * - * Note that because of how tlb_next_batch() above works, we will - * never start multiple new batches with pending delayed rmaps, so - * we only need to walk through the current active batch and the - * original local one. + * Removes rmap from all pages added via (e.g.) __tlb_remove_page_size() since + * the last call to tlb_discard_rmaps() or tlb_flush_rmaps(). All of those pages + * must have been mapped by vma. Must be called after the pte(s) are cleared, + * and before the ptl lock that was held for clearing the pte is released. Pages + * are accounted using the order-0 folio (or base page) scheme. */ void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma) { - if (!tlb->delayed_rmap) - return; + struct mmu_gather_batch *batch = tlb->rmap_pend; - tlb_flush_rmap_batch(&tlb->local, vma); - if (tlb->active != &tlb->local) - tlb_flush_rmap_batch(tlb->active, vma); - tlb->delayed_rmap = 0; + tlb_flush_rmap_batch(batch, tlb->rmap_pend_first, vma); + + for (batch = batch->next; batch && batch->nr; batch = batch->next) + tlb_flush_rmap_batch(batch, 0, vma); + + tlb_discard_rmaps(tlb); +} + +/** + * tlb_discard_rmaps - discard any pending rmap removals + * @tlb: the current mmu_gather + */ +void tlb_discard_rmaps(struct mmu_gather *tlb) +{ + tlb->rmap_pend = tlb->active; + tlb->rmap_pend_first = tlb->active->nr; } #endif @@ -103,6 +111,7 @@ static void tlb_batch_pages_flush(struct mmu_gather *tlb) } while (batch->nr); } tlb->active = &tlb->local; + tlb_discard_rmaps(tlb); } static void tlb_batch_list_free(struct mmu_gather *tlb) @@ -313,8 +322,9 @@ static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, tlb->local.max = ARRAY_SIZE(tlb->__pages); tlb->active = &tlb->local; tlb->batch_count = 0; + tlb->rmap_pend = &tlb->local; + tlb->rmap_pend_first = 0; #endif - tlb->delayed_rmap = 0; tlb_table_init(tlb); #ifdef CONFIG_MMU_GATHER_PAGE_SIZE From patchwork Wed Aug 30 09:50:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370145 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E154C6FA8F for ; Wed, 30 Aug 2023 09:50:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 048A3280050; Wed, 30 Aug 2023 05:50:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F13A628004E; Wed, 30 Aug 2023 05:50:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D8CF3280050; Wed, 30 Aug 2023 05:50:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id C84CC28004E for ; Wed, 30 Aug 2023 05:50:39 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 8E8F6120173 for ; Wed, 30 Aug 2023 09:50:39 +0000 (UTC) X-FDA: 81180301398.25.D90BD8B Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf09.hostedemail.com (Postfix) with ESMTP id C963A140004 for ; Wed, 30 Aug 2023 09:50:37 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf09.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389037; a=rsa-sha256; cv=none; b=SgEsTn/DvF5naDxu8V3PGq8XW8cjyA5UAp2CLNWQ6Ba2fOOJkLIZ+IyV71Ot7lLI5nPfAF gqmAoDKLb5n0C+PC0tHTGQO5GqNRv7RJlkAmRKbPjMK5XT+G6Hdi0BJ7uGjnc+tQTjQJMd H0jn76JX2FLfnlkT8l+dz5iBK28/VIA= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf09.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389037; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wmrVLSJPa0RjCTuS+lqhx0P0ZiJJRUlJnABwX77Ults=; b=ERxVOv+QyQ0FGyTlxvl4dSoscOoGZ1QirnEKqwx0nKayTA6Y/v4ZpP2dBL5KQ4djz5MPVn Z5Aeg/cFvtVS10ISQNllwT3/fBh8J9EvMx0luqjsWeOla/Ca37uwystZPeYKSh7gkxHZmX MtmKXVuDALdxsV1eo0O4ufrloR3Ljz4= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 646692F4; Wed, 30 Aug 2023 02:51:16 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 659443F64C; Wed, 30 Aug 2023 02:50:34 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/5] mm/mmu_gather: Remove encoded_page infrastructure Date: Wed, 30 Aug 2023 10:50:09 +0100 Message-Id: <20230830095011.1228673-4-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: C963A140004 X-Stat-Signature: tw4iwkgqqtfi941qwhmu6bmdm4s7hmo8 X-Rspam-User: X-HE-Tag: 1693389037-351918 X-HE-Meta: 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 ozyjutUv /AibESeO7NbBhHKd/csGC2GcJ3KaveCJjBVmwSzQf5+Eaa7ocUHECboNMEt8NZemqaZgx5zc/V+ZwdWAivpT1OBcRno4f7SuKNbU4MOFOIlbFMojz8RxA0NeHGK8Lj1U1andIhblheviQ6+XsOp5OSK0JN5HUGA/dUaxsLel1HzEVDKhfGLt5nGeu0ue/eissmPUWlUgaY/CJJRg= 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: commit 70fb4fdff582 ("mm: introduce 'encoded' page pointers with embedded extra bits") and commit 7cc8f9c7146a ("mm: mmu_gather: prepare to gather encoded page pointers with flags") converted mmu_gather for dealing with encoded_page, where the bottom 2 bits could encode extra flags. Only 1 bit was ever used; to flag whether the page should participate in a delayed rmap removal. Now that the mmu_gather batched rmap removal mechanism has been generalized, all pages participate and therefore the flag is unused. So let's remove encoded_page to simplify the code. It also gets in the way of further optimization which will be done in a follow up patch. Signed-off-by: Ryan Roberts --- arch/s390/include/asm/tlb.h | 9 +++------ include/asm-generic/tlb.h | 10 +++++----- include/linux/mm.h | 4 +--- include/linux/mm_types.h | 34 +--------------------------------- include/linux/swap.h | 2 +- mm/memory.c | 2 +- mm/mmu_gather.c | 11 +++++------ mm/swap.c | 8 +++----- mm/swap_state.c | 4 ++-- 9 files changed, 22 insertions(+), 62 deletions(-) diff --git a/arch/s390/include/asm/tlb.h b/arch/s390/include/asm/tlb.h index 383b1f91442c..c40b44f6a31b 100644 --- a/arch/s390/include/asm/tlb.h +++ b/arch/s390/include/asm/tlb.h @@ -25,7 +25,7 @@ void __tlb_remove_table(void *_table); static inline void tlb_flush(struct mmu_gather *tlb); static inline bool __tlb_remove_page_size(struct mmu_gather *tlb, - struct encoded_page *page, + struct page *page, int page_size); #define tlb_flush tlb_flush @@ -41,15 +41,12 @@ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb, * Release the page cache reference for a pte removed by * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page * has already been freed, so just do free_page_and_swap_cache. - * - * s390 doesn't delay rmap removal, so there is nothing encoded in - * the page pointer. */ static inline bool __tlb_remove_page_size(struct mmu_gather *tlb, - struct encoded_page *page, + struct page *page, int page_size) { - free_page_and_swap_cache(encoded_page_ptr(page)); + free_page_and_swap_cache(page); return false; } diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index f339d68cf44f..d874415aaa33 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -246,7 +246,7 @@ struct mmu_gather_batch { struct mmu_gather_batch *next; unsigned int nr; unsigned int max; - struct encoded_page *encoded_pages[]; + struct page *pages[]; }; #define MAX_GATHER_BATCH \ @@ -261,7 +261,7 @@ struct mmu_gather_batch { #define MAX_GATHER_BATCH_COUNT (10000UL/MAX_GATHER_BATCH) extern bool __tlb_remove_page_size(struct mmu_gather *tlb, - struct encoded_page *page, + struct page *page, int page_size); #ifdef CONFIG_SMP @@ -464,13 +464,13 @@ static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) static inline void tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size) { - if (__tlb_remove_page_size(tlb, encode_page(page, 0), page_size)) + if (__tlb_remove_page_size(tlb, page, page_size)) tlb_flush_mmu(tlb); } -static __always_inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page, unsigned int flags) +static __always_inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page) { - return __tlb_remove_page_size(tlb, encode_page(page, flags), PAGE_SIZE); + return __tlb_remove_page_size(tlb, page, PAGE_SIZE); } /* tlb_remove_page diff --git a/include/linux/mm.h b/include/linux/mm.h index 53efddc4d178..9cd20a38089c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1481,8 +1481,7 @@ static inline void folio_put_refs(struct folio *folio, int refs) * * release_pages() releases a simple array of multiple pages, and * accepts various different forms of said page array: either - * a regular old boring array of pages, an array of folios, or - * an array of encoded page pointers. + * a regular old boring array of pages or an array of folios. * * The transparent union syntax for this kind of "any of these * argument types" is all kinds of ugly, so look away. @@ -1490,7 +1489,6 @@ static inline void folio_put_refs(struct folio *folio, int refs) typedef union { struct page **pages; struct folio **folios; - struct encoded_page **encoded_pages; } release_pages_arg __attribute__ ((__transparent_union__)); void release_pages(release_pages_arg, int nr); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 5a995089cbf5..e9a0daf0c8d4 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -68,7 +68,7 @@ struct mem_cgroup; #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE #define _struct_page_alignment __aligned(2 * sizeof(unsigned long)) #else -#define _struct_page_alignment __aligned(sizeof(unsigned long)) +#define _struct_page_alignment #endif struct page { @@ -216,38 +216,6 @@ struct page { #endif } _struct_page_alignment; -/* - * struct encoded_page - a nonexistent type marking this pointer - * - * An 'encoded_page' pointer is a pointer to a regular 'struct page', but - * with the low bits of the pointer indicating extra context-dependent - * information. Not super-common, but happens in mmu_gather and mlock - * handling, and this acts as a type system check on that use. - * - * We only really have two guaranteed bits in general, although you could - * play with 'struct page' alignment (see CONFIG_HAVE_ALIGNED_STRUCT_PAGE) - * for more. - * - * Use the supplied helper functions to endcode/decode the pointer and bits. - */ -struct encoded_page; -#define ENCODE_PAGE_BITS 3ul -static __always_inline struct encoded_page *encode_page(struct page *page, unsigned long flags) -{ - BUILD_BUG_ON(flags > ENCODE_PAGE_BITS); - return (struct encoded_page *)(flags | (unsigned long)page); -} - -static inline unsigned long encoded_page_flags(struct encoded_page *page) -{ - return ENCODE_PAGE_BITS & (unsigned long)page; -} - -static inline struct page *encoded_page_ptr(struct encoded_page *page) -{ - return (struct page *)(~ENCODE_PAGE_BITS & (unsigned long)page); -} - /* * A swap entry has to fit into a "unsigned long", as the entry is hidden * in the "index" field of the swapper address space. diff --git a/include/linux/swap.h b/include/linux/swap.h index 493487ed7c38..9e12c6d49997 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -451,7 +451,7 @@ static inline unsigned long total_swapcache_pages(void) extern void free_swap_cache(struct page *page); extern void free_page_and_swap_cache(struct page *); -extern void free_pages_and_swap_cache(struct encoded_page **, int); +extern void free_pages_and_swap_cache(struct page **, int); /* linux/mm/swapfile.c */ extern atomic_long_t nr_swap_pages; extern long total_swap_pages; diff --git a/mm/memory.c b/mm/memory.c index 823c8a6813d1..3d5d395caba4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1460,7 +1460,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, if (unlikely(page_mapcount(page) < 0)) print_bad_pte(vma, addr, ptent, page); } - if (unlikely(__tlb_remove_page(tlb, page, 0))) { + if (unlikely(__tlb_remove_page(tlb, page))) { force_flush = 1; addr += PAGE_SIZE; break; diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c index fb34151c0da9..cdebb5b9f5c4 100644 --- a/mm/mmu_gather.c +++ b/mm/mmu_gather.c @@ -49,8 +49,7 @@ static void tlb_flush_rmap_batch(struct mmu_gather_batch *batch, struct vm_area_struct *vma) { for (int i = first; i < batch->nr; i++) { - struct encoded_page *enc = batch->encoded_pages[i]; - struct page *page = encoded_page_ptr(enc); + struct page *page = batch->pages[i]; page_remove_rmap(page, vma, false); } @@ -95,7 +94,7 @@ static void tlb_batch_pages_flush(struct mmu_gather *tlb) struct mmu_gather_batch *batch; for (batch = &tlb->local; batch && batch->nr; batch = batch->next) { - struct encoded_page **pages = batch->encoded_pages; + struct page **pages = batch->pages; do { /* @@ -125,7 +124,7 @@ static void tlb_batch_list_free(struct mmu_gather *tlb) tlb->local.next = NULL; } -bool __tlb_remove_page_size(struct mmu_gather *tlb, struct encoded_page *page, int page_size) +bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size) { struct mmu_gather_batch *batch; @@ -140,13 +139,13 @@ bool __tlb_remove_page_size(struct mmu_gather *tlb, struct encoded_page *page, i * Add the page and check if we are full. If so * force a flush. */ - batch->encoded_pages[batch->nr++] = page; + batch->pages[batch->nr++] = page; if (batch->nr == batch->max) { if (!tlb_next_batch(tlb)) return true; batch = tlb->active; } - VM_BUG_ON_PAGE(batch->nr > batch->max, encoded_page_ptr(page)); + VM_BUG_ON_PAGE(batch->nr > batch->max, page); return false; } diff --git a/mm/swap.c b/mm/swap.c index cd8f0150ba3a..b05cce475202 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -953,14 +953,12 @@ void lru_cache_disable(void) * 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. + * Note that the argument can be an array of pages or folio pointers. */ void release_pages(release_pages_arg arg, int nr) { int i; - struct encoded_page **encoded = arg.encoded_pages; + struct page **pages = arg.pages; LIST_HEAD(pages_to_free); struct lruvec *lruvec = NULL; unsigned long flags = 0; @@ -970,7 +968,7 @@ void release_pages(release_pages_arg arg, int nr) struct folio *folio; /* Turn any of the argument types into a folio */ - folio = page_folio(encoded_page_ptr(encoded[i])); + folio = page_folio(pages[i]); /* * Make sure the IRQ-safe lock-holding time does not get diff --git a/mm/swap_state.c b/mm/swap_state.c index b3b14bd0dd64..2132340c6e61 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -307,11 +307,11 @@ void free_page_and_swap_cache(struct page *page) * Passed an array of pages, drop them all from swapcache and then release * them. They are removed from the LRU and freed if this is their last use. */ -void free_pages_and_swap_cache(struct encoded_page **pages, int nr) +void free_pages_and_swap_cache(struct page **pages, int nr) { lru_add_drain(); for (int i = 0; i < nr; i++) - free_swap_cache(encoded_page_ptr(pages[i])); + free_swap_cache(pages[i]); release_pages(pages, nr); } From patchwork Wed Aug 30 09:50:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370146 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 243EFC83F14 for ; Wed, 30 Aug 2023 09:50:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A3252280051; Wed, 30 Aug 2023 05:50:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9BC1E28004E; Wed, 30 Aug 2023 05:50:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 83657280051; Wed, 30 Aug 2023 05:50:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 7375A28004E for ; Wed, 30 Aug 2023 05:50:42 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 4EC11B2B95 for ; Wed, 30 Aug 2023 09:50:42 +0000 (UTC) X-FDA: 81180301524.09.E80CBE1 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf27.hostedemail.com (Postfix) with ESMTP id 8FC1F40012 for ; Wed, 30 Aug 2023 09:50:40 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf27.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389040; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G17L5TxSQCpiXEhkpkLQWUKlMnog/0uc4pVDC0rr5Ls=; b=D44HS3+JsoumtT8y6KiV6CfSPvei645VxVBS0DliA9cSN2IS/rsstvT6XB86MDZoOa17w3 /kMTwQ1guoJcyKGjD5wwZD7y0mRVAvXbDKml/xAOT5I4XIVhmCBpzeJbksh+gsa8cb8MmI Mp27nBwdYjl/inTAqdNLzXH0mxjc1qI= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf27.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389040; a=rsa-sha256; cv=none; b=WLcxuT5zysdukOzJ95xKS0sMzSvrIf6PlKts471ydlnBDThba501omkm31N0kux0WG9NwD zry0mJLCJMH1DVqrTNiqoNwc5AWh5vNCuNsrSXq0DpwvpEDToH3wv91nqEAmh5FiI8c0oy ddy2V8QneFwonqPrsc1CfZ0rvI8Adh8= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3CB9DFEC; Wed, 30 Aug 2023 02:51:19 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3A5003F64C; Wed, 30 Aug 2023 02:50:37 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 4/5] mm: Refector release_pages() Date: Wed, 30 Aug 2023 10:50:10 +0100 Message-Id: <20230830095011.1228673-5-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 8FC1F40012 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 4qig5csr77nqk8gbh5bwfk4efrrd1sau X-HE-Tag: 1693389040-107007 X-HE-Meta: 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 BYYWHJ+8 DhcKFvsy6rVtspESEZjCQlEHa+ZQKB+L+aTtIqYHxPPdjQuYlGsyMEcoXFJqCG/rDNOQ9DmCWYP24CqhhE3sW9awE7i8gGcTY9zu18bIKliU2BWoVYyaaVRPqe1S5GXPIcfFzRc69eLax9hvJsiAZSJS3oChAXyOwdEgVbFpyU3pGamTfKQhZLDiUi69/q7UQmn27me4X6Nkxt/M= 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: In preparation for implementing folios_put_refs() in the next patch, refactor release_pages() into a set of helper functions, which can be reused. The primary difference between release_pages() and folios_put_refs() is how they iterate over the set of folios. The per-folio actions are identical. No functional change intended. Signed-off-by: Ryan Roberts --- mm/swap.c | 167 +++++++++++++++++++++++++++++++----------------------- 1 file changed, 97 insertions(+), 70 deletions(-) diff --git a/mm/swap.c b/mm/swap.c index b05cce475202..5d3e35668929 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -945,6 +945,98 @@ void lru_cache_disable(void) #endif } +struct folios_put_refs_ctx { + struct list_head pages_to_free; + struct lruvec *lruvec; + unsigned long flags; + unsigned int lock_batch; +}; + +static void __folios_put_refs_init(struct folios_put_refs_ctx *ctx) +{ + *ctx = (struct folios_put_refs_ctx) { + .pages_to_free = LIST_HEAD_INIT(ctx->pages_to_free), + .lruvec = NULL, + .flags = 0, + }; +} + +static void __folios_put_refs_complete(struct folios_put_refs_ctx *ctx) +{ + if (ctx->lruvec) + unlock_page_lruvec_irqrestore(ctx->lruvec, ctx->flags); + + mem_cgroup_uncharge_list(&ctx->pages_to_free); + free_unref_page_list(&ctx->pages_to_free); +} + +static void __folios_put_refs_do_one(struct folios_put_refs_ctx *ctx, + struct folio *folio, int refs) +{ + /* + * 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 (ctx->lruvec && ++ctx->lock_batch == SWAP_CLUSTER_MAX) { + unlock_page_lruvec_irqrestore(ctx->lruvec, ctx->flags); + ctx->lruvec = NULL; + } + + if (is_huge_zero_page(&folio->page)) + return; + + if (folio_is_zone_device(folio)) { + if (ctx->lruvec) { + unlock_page_lruvec_irqrestore(ctx->lruvec, ctx->flags); + ctx->lruvec = NULL; + } + if (put_devmap_managed_page_refs(&folio->page, refs)) + return; + if (folio_ref_sub_and_test(folio, refs)) + free_zone_device_page(&folio->page); + return; + } + + if (!folio_ref_sub_and_test(folio, refs)) + return; + + if (folio_test_large(folio)) { + if (ctx->lruvec) { + unlock_page_lruvec_irqrestore(ctx->lruvec, ctx->flags); + ctx->lruvec = NULL; + } + __folio_put_large(folio); + return; + } + + if (folio_test_lru(folio)) { + struct lruvec *prev_lruvec = ctx->lruvec; + + ctx->lruvec = folio_lruvec_relock_irqsave(folio, ctx->lruvec, + &ctx->flags); + if (prev_lruvec != ctx->lruvec) + ctx->lock_batch = 0; + + lruvec_del_folio(ctx->lruvec, folio); + __folio_clear_lru_flags(folio); + } + + /* + * In rare cases, when truncation or holepunching raced with + * munlock after VM_LOCKED was cleared, Mlocked may still be + * found set here. This does not indicate a problem, unless + * "unevictable_pgs_cleared" appears worryingly large. + */ + if (unlikely(folio_test_mlocked(folio))) { + __folio_clear_mlocked(folio); + zone_stat_sub_folio(folio, NR_MLOCK); + count_vm_event(UNEVICTABLE_PGCLEARED); + } + + list_add(&folio->lru, &ctx->pages_to_free); +} + /** * release_pages - batched put_page() * @arg: array of pages to release @@ -959,10 +1051,9 @@ void release_pages(release_pages_arg arg, int nr) { int i; struct page **pages = arg.pages; - LIST_HEAD(pages_to_free); - struct lruvec *lruvec = NULL; - unsigned long flags = 0; - unsigned int lock_batch; + struct folios_put_refs_ctx ctx; + + __folios_put_refs_init(&ctx); for (i = 0; i < nr; i++) { struct folio *folio; @@ -970,74 +1061,10 @@ void release_pages(release_pages_arg arg, int nr) /* Turn any of the argument types into a folio */ folio = page_folio(pages[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; - } - - if (is_huge_zero_page(&folio->page)) - continue; - - if (folio_is_zone_device(folio)) { - if (lruvec) { - unlock_page_lruvec_irqrestore(lruvec, flags); - lruvec = NULL; - } - if (put_devmap_managed_page(&folio->page)) - continue; - if (folio_put_testzero(folio)) - free_zone_device_page(&folio->page); - continue; - } - - if (!folio_put_testzero(folio)) - continue; - - if (folio_test_large(folio)) { - if (lruvec) { - unlock_page_lruvec_irqrestore(lruvec, flags); - lruvec = NULL; - } - __folio_put_large(folio); - continue; - } - - 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); - } - - /* - * In rare cases, when truncation or holepunching raced with - * munlock after VM_LOCKED was cleared, Mlocked may still be - * found set here. This does not indicate a problem, unless - * "unevictable_pgs_cleared" appears worryingly large. - */ - if (unlikely(folio_test_mlocked(folio))) { - __folio_clear_mlocked(folio); - zone_stat_sub_folio(folio, NR_MLOCK); - count_vm_event(UNEVICTABLE_PGCLEARED); - } - - list_add(&folio->lru, &pages_to_free); + __folios_put_refs_do_one(&ctx, folio, 1); } - if (lruvec) - unlock_page_lruvec_irqrestore(lruvec, flags); - mem_cgroup_uncharge_list(&pages_to_free); - free_unref_page_list(&pages_to_free); + __folios_put_refs_complete(&ctx); } EXPORT_SYMBOL(release_pages); From patchwork Wed Aug 30 09:50:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13370147 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFCAAC83F15 for ; Wed, 30 Aug 2023 09:50:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6D67F280052; Wed, 30 Aug 2023 05:50:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 661B528004E; Wed, 30 Aug 2023 05:50:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4DA0D280052; Wed, 30 Aug 2023 05:50:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 3B07B28004E for ; Wed, 30 Aug 2023 05:50:45 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 1217E1A0399 for ; Wed, 30 Aug 2023 09:50:45 +0000 (UTC) X-FDA: 81180301650.17.2FE15B1 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf29.hostedemail.com (Postfix) with ESMTP id 592BE12001A for ; Wed, 30 Aug 2023 09:50:43 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=none; spf=pass (imf29.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1693389043; a=rsa-sha256; cv=none; b=u9eTcGwAVfLw7tWEs8P2czc1Iw2PoeSxIcafNrq2g9G208UDP0JsJCOe0we6To9jtEZAi8 wQo4EVN/mBwGitLxvxV57Be+agNIPHzsDYfo9U+UyLzqprgbJigRaAn3qDBA43Wc6zZ4yQ sUjDqdQjd0Y8+daclkI1gtKQ7bq6/x8= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=none; spf=pass (imf29.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1693389043; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CLU8LwNZDR7I4UCGz6ORIx41V8pNYVe+6lLXPyWaccE=; b=lZGoHMDAfV6Udn1xkF2Tp1GBas+tw80PvJ3c3545pQEwTdzfWj7AQQWqorxLYEOCMBLtw5 EaxES58a991FC+HDX04DkPY8mMIkaDexEhgiaxps4Q2+egYNEkJ9I84s2Ahjh7qBUc8nEj CDh9psYMdvDgqIz6kUG62d5wxqWJcQw= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0E52A2F4; Wed, 30 Aug 2023 02:51:22 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0F7E13F64C; Wed, 30 Aug 2023 02:50:39 -0700 (PDT) From: Ryan Roberts To: Will Deacon , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Peter Zijlstra , Christian Borntraeger , Sven Schnelle , Arnd Bergmann , "Matthew Wilcox (Oracle)" , David Hildenbrand , Yu Zhao , "Kirill A. Shutemov" , Yin Fengwei , Yang Shi , "Huang, Ying" , Zi Yan Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 5/5] mm/mmu_gather: Store and process pages in contig ranges Date: Wed, 30 Aug 2023 10:50:11 +0100 Message-Id: <20230830095011.1228673-6-ryan.roberts@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230830095011.1228673-1-ryan.roberts@arm.com> References: <20230830095011.1228673-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 592BE12001A X-Stat-Signature: hunutoer4nd3apiweowztrgsofniyr6a X-HE-Tag: 1693389043-341928 X-HE-Meta: U2FsdGVkX18/RTJrEsHtddlyzSANOO3LP4Comkrrb4yQRmh5s9HuCT6kJ5hyOG7NY23n7LpSifyrd4i04n2PsYDlN5kMqajgEj3WKR7fgOkSlyGXkyHkGq3z1vHMTbjuyeYZkeBGZt/WCnBQleKmWrRG5Kn/8CWvSM++xAzjB/TZrnTi9+lzGKJeInfSHSiQeZ49gIsvoiVKtqSsMLHu8kVfn8A8UWeOQyzelJYF55sgZ+nhI3fXJPe/jgt0M9tmbd56MhJWYoEzkQef9odq0qSOoG/WmthZ6umq/AodaHy/KUH5FKuv7dQzNKTrmuE/rvzU+bw3Xe7EIUH71uYvdUbAZYI5NQh854MyQ5b8o6sfaTo/gZzhxhWgkIpYbSxYxN4aY8kApGxJLI4Y5vobbfxFhSAxoqx0cqsKF54urF6wCH5Z+aC0b4SyzbGBveED3w/7L8iZVBKzUgkrzAtgJOJpxtNZ4iHjUad50DcyPvyH22dcA0/czXgL1mjsV+5tsHKjxSmubo3M5EllIlIFgP+IETLsVu5rXJ9WiQMhQ6OoYNrXwxWj04WaC9kZ5gUnxOrYp4c3B9hmxRNqK/Lg7Ic9AF9JKON2DSy92GwHnkPp+25MOYR/Dnx9Md82b+/mp5KKYMMTrWaiUjoGFZabgJyfKaRN6NDiVoY4k7xVu7K++sNidqI+M1CWaxNZv6KWd5Y0nkywVUTsU6m714D8AZ5Lkc2YH6mKN55svhIR50R6iQJlM/a5MP29LB0ACu/xb4n/HIHEGKcHkrOjeO+DgEOTj6pUOV8L/y28sBJ2sZxb6cenSv/W3rtx5JI1B6ChtE0y6sMG+4zgefYT015JJED9wzaYAks78ZUH8Ndh3AcKOdMIF9KjzEVwHXbbeQLlNKNPgD2rX6GQu6Yrx8Z9lqgWD70e+WpiaqNgrEBEh7DbUFHoYVQEO/JHzFZTr2FDa2ybFztVdHHHPyr10yz dJRJQXFE f6P++Ttg/XQKVSLXzEdqMq7vki/Hr20YbuTHr5C7M8adYodnDI7HS67j4fmIzptN6qtFgx5bNQn7+XfI7T3ngAjhl7s3qz/ekWdCd220rUOos/nHNS/wiG+zpU+RULIp6uhx/5v9XJAD5DfAei/ZPbhshl3BHrMqEmdqG01rBooffScS5fEFMHvMWiTXHGGyfrWEBjtMRLqmt08c= 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: mmu_gather accumulates a set of pages into a buffer for later rmap removal and freeing. Page pointers were previously stored in a "linked list of arrays", then at flush time, each page in the buffer was removed from the rmap, removed from the swapcache and its refcount was decremented; if the refcount reached 0, then it was freed. With increasing numbers of large folios (or at least contiguous parts of large folios) mapped into userspace processes (pagecache pages for supporting filesystems currently, but in future also large anonymous folios), we can measurably improve performance of process teardown: - For rmap removal, we can batch-remove a range of pages belonging to the same folio with folio_remove_rmap_range(), which is more efficient because atomics can be manipulated just once per range. In the common case, it also allows us to elide adding the (anon) folio to the deferred split queue, only to remove it a bit later, once all pages of the folio have been removed fro mthe rmap. - For swapcache removal, we only need to check and remove the folio from the swap cache once, rather than trying for each individual page. - For page release, we can batch-decrement the refcount for each page in the folio and free it if it hits zero. Change the page pointer storage format within the mmu_gather batch structure to store "pfn_range"s; a [start, end) pfn pair. This allows us to run length encode a contiguous range of pages that all belong to the same folio. This likely allows us to improve cache locality a bit. But it also gives us a convenient format for implementing the above 3 optimizations. Of course if running on a system that does not extensively use large pte-mapped folios, then the RLE approach uses twice as much memory, because each range is 1 page long and uses 2 words. But performance measurements show no impact in terms of performance. Macro Performance Results ------------------------- Test: Timed kernel compilation on Ampere Altra (arm64), 80 jobs Configs: Comparing with and without large anon folios Without large anon folios: | kernel | real-time | kern-time | user-time | |:-----------------|------------:|------------:|------------:| | baseline-laf-off | 0.0% | 0.0% | 0.0% | | mmugather-range | -0.3% | -0.3% | 0.1% | With large anon folios (order-3): | kernel | real-time | kern-time | user-time | |:-----------------|------------:|------------:|------------:| | baseline-laf-on | 0.0% | 0.0% | 0.0% | | mmugather-range | -0.7% | -3.9% | -0.1% | Test: Timed kernel compilation in VM on Apple M2 MacBook Pro, 8 jobs Configs: Comparing with and without large anon folios Without large anon folios: | kernel | real-time | kern-time | user-time | |:-----------------|------------:|------------:|------------:| | baseline-laf-off | 0.0% | 0.0% | 0.0% | | mmugather-range | -0.9% | -2.9% | -0.6% | With large anon folios (order-3): | kernel | real-time | kern-time | user-time | |:-----------------|------------:|------------:|------------:| | baseline-laf-on | 0.0% | 0.0% | 0.0% | | mmugather-range | -0.4% | -3.7% | -0.2% | Micro Performance Results ------------------------- Flame graphs for kernel compilation on Ampere Altra show reduction in cycles consumed by __arm64_sys_exit_group syscall: Without large anon folios: -2% With large anon folios: -26% For the large anon folios case, it also shows a big difference in cost of rmap removal: baseline: cycles in page_remove_rmap(): 24.7B mmugather-range: cycles in folio_remove_rmap_range(): 5.5B Furthermore, the baseline shows 5.2B cycles used by deferred_split_folio() which has completely disappeared after applying this series. Signed-off-by: Ryan Roberts --- include/asm-generic/tlb.h | 7 +++-- include/linux/mm.h | 7 +++++ include/linux/swap.h | 6 ++-- mm/mmu_gather.c | 59 +++++++++++++++++++++++++++++++++------ mm/swap.c | 26 +++++++++++++++++ mm/swap_state.c | 11 ++++---- 6 files changed, 96 insertions(+), 20 deletions(-) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index d874415aaa33..04e23cad6d1f 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -246,11 +246,11 @@ struct mmu_gather_batch { struct mmu_gather_batch *next; unsigned int nr; unsigned int max; - struct page *pages[]; + struct pfn_range folios[]; }; #define MAX_GATHER_BATCH \ - ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) + ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(struct pfn_range)) /* * Limit the maximum number of mmu_gather batches to reduce a risk of soft @@ -342,7 +342,8 @@ struct mmu_gather { #ifndef CONFIG_MMU_GATHER_NO_GATHER struct mmu_gather_batch *active; struct mmu_gather_batch local; - struct page *__pages[MMU_GATHER_BUNDLE]; + struct pfn_range __folios[MMU_GATHER_BUNDLE]; + unsigned long range_limit; struct mmu_gather_batch *rmap_pend; unsigned int rmap_pend_first; diff --git a/include/linux/mm.h b/include/linux/mm.h index 9cd20a38089c..f62d3d8ea0e4 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1476,6 +1476,13 @@ static inline void folio_put_refs(struct folio *folio, int refs) __folio_put(folio); } +struct pfn_range { + unsigned long start; + unsigned long end; +}; + +void folios_put_refs(struct pfn_range *folios, int nr); + /* * union release_pages_arg - an array of pages or folios * diff --git a/include/linux/swap.h b/include/linux/swap.h index 9e12c6d49997..cd12056a6a5f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -451,7 +451,7 @@ static inline unsigned long total_swapcache_pages(void) extern void free_swap_cache(struct page *page); extern void free_page_and_swap_cache(struct page *); -extern void free_pages_and_swap_cache(struct page **, int); +extern void free_folios_and_swap_cache(struct pfn_range *, int); /* linux/mm/swapfile.c */ extern atomic_long_t nr_swap_pages; extern long total_swap_pages; @@ -528,8 +528,8 @@ static inline void put_swap_device(struct swap_info_struct *si) * so leave put_page and release_pages undeclared... */ #define free_page_and_swap_cache(page) \ put_page(page) -#define free_pages_and_swap_cache(pages, nr) \ - release_pages((pages), (nr)); +#define free_folios_and_swap_cache(folios, nr) \ + folios_put_refs((folios), (nr)) /* used to sanity check ptes in zap_pte_range when CONFIG_SWAP=0 */ #define free_swap_and_cache(e) is_pfn_swap_entry(e) diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c index cdebb5b9f5c4..c8687ce07ce0 100644 --- a/mm/mmu_gather.c +++ b/mm/mmu_gather.c @@ -22,6 +22,7 @@ static bool tlb_next_batch(struct mmu_gather *tlb) batch = tlb->active; if (batch->next) { tlb->active = batch->next; + tlb->range_limit = ULONG_MAX; return true; } @@ -39,6 +40,7 @@ static bool tlb_next_batch(struct mmu_gather *tlb) tlb->active->next = batch; tlb->active = batch; + tlb->range_limit = ULONG_MAX; return true; } @@ -49,9 +51,12 @@ static void tlb_flush_rmap_batch(struct mmu_gather_batch *batch, struct vm_area_struct *vma) { for (int i = first; i < batch->nr; i++) { - struct page *page = batch->pages[i]; + struct pfn_range *range = &batch->folios[i]; + int nr = range->end - range->start; + struct page *start = pfn_to_page(range->start); + struct folio *folio = page_folio(start); - page_remove_rmap(page, vma, false); + folio_remove_rmap_range(folio, start, nr, vma); } } @@ -75,6 +80,11 @@ void tlb_flush_rmaps(struct mmu_gather *tlb, struct vm_area_struct *vma) for (batch = batch->next; batch && batch->nr; batch = batch->next) tlb_flush_rmap_batch(batch, 0, vma); + /* + * Move to the next range on next page insertion to prevent any future + * pages from being accumulated into the range we just did the rmap for. + */ + tlb->range_limit = ULONG_MAX; tlb_discard_rmaps(tlb); } @@ -94,7 +104,7 @@ static void tlb_batch_pages_flush(struct mmu_gather *tlb) struct mmu_gather_batch *batch; for (batch = &tlb->local; batch && batch->nr; batch = batch->next) { - struct page **pages = batch->pages; + struct pfn_range *folios = batch->folios; do { /* @@ -102,14 +112,15 @@ static void tlb_batch_pages_flush(struct mmu_gather *tlb) */ unsigned int nr = min(512U, batch->nr); - free_pages_and_swap_cache(pages, nr); - pages += nr; + free_folios_and_swap_cache(folios, nr); + folios += nr; batch->nr -= nr; cond_resched(); } while (batch->nr); } tlb->active = &tlb->local; + tlb->range_limit = ULONG_MAX; tlb_discard_rmaps(tlb); } @@ -127,6 +138,8 @@ static void tlb_batch_list_free(struct mmu_gather *tlb) bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size) { struct mmu_gather_batch *batch; + struct pfn_range *range; + unsigned long pfn = page_to_pfn(page); VM_BUG_ON(!tlb->end); @@ -135,11 +148,38 @@ bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_ #endif batch = tlb->active; + range = &batch->folios[batch->nr - 1]; + + /* + * If there is a range being accumulated, add the pfn to the range if + * its contiguous, else start the next range. range_limit is always + * ULONG_MAX when nr is 0, which protects the batch->folios[-1] case. + */ + if (tlb->range_limit != ULONG_MAX && pfn == range->end) { + range->end++; + } else { + struct folio *folio = page_folio(page); + + range = &batch->folios[batch->nr++]; + range->start = pfn; + range->end = pfn + 1; + + tlb->range_limit = page_to_pfn(&folio->page) + + folio_nr_pages(folio); + } + + /* + * If we have reached the end of the folio, move to the next range when + * we add the next page; Never span multiple folios in the same range. + */ + if (range->end == tlb->range_limit) + tlb->range_limit = ULONG_MAX; + /* - * Add the page and check if we are full. If so - * force a flush. + * Check if we are full. If so force a flush. In order to ensure we + * always have a free range for the next added page, the last range in a + * batch always only has a single page. */ - batch->pages[batch->nr++] = page; if (batch->nr == batch->max) { if (!tlb_next_batch(tlb)) return true; @@ -318,8 +358,9 @@ static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, tlb->need_flush_all = 0; tlb->local.next = NULL; tlb->local.nr = 0; - tlb->local.max = ARRAY_SIZE(tlb->__pages); + tlb->local.max = ARRAY_SIZE(tlb->__folios); tlb->active = &tlb->local; + tlb->range_limit = ULONG_MAX; tlb->batch_count = 0; tlb->rmap_pend = &tlb->local; tlb->rmap_pend_first = 0; diff --git a/mm/swap.c b/mm/swap.c index 5d3e35668929..d777f2b47674 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -1037,6 +1037,32 @@ static void __folios_put_refs_do_one(struct folios_put_refs_ctx *ctx, list_add(&folio->lru, &ctx->pages_to_free); } +/** + * folios_put_refs - batched folio_put_refs() + * @folios: array of `struct pfn_range`s to release + * @nr: number of folio ranges + * + * Each `struct pfn_range` describes the start and end pfn of a range within a + * single folio. The folio reference count is decremented once for each pfn in + * the range. If it fell to zero, remove the page from the LRU and free it. + */ +void folios_put_refs(struct pfn_range *folios, int nr) +{ + int i; + struct folios_put_refs_ctx ctx; + + __folios_put_refs_init(&ctx); + + for (i = 0; i < nr; i++) { + struct folio *folio = pfn_folio(folios[i].start); + int refs = folios[i].end - folios[i].start; + + __folios_put_refs_do_one(&ctx, folio, refs); + } + + __folios_put_refs_complete(&ctx); +} + /** * release_pages - batched put_page() * @arg: array of pages to release diff --git a/mm/swap_state.c b/mm/swap_state.c index 2132340c6e61..900e57bf9882 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -304,15 +304,16 @@ void free_page_and_swap_cache(struct page *page) } /* - * Passed an array of pages, drop them all from swapcache and then release - * them. They are removed from the LRU and freed if this is their last use. + * Passed an array of folio ranges, drop all folios from swapcache and then put + * a folio reference for each page in the range. They are removed from the LRU + * and freed if this is their last use. */ -void free_pages_and_swap_cache(struct page **pages, int nr) +void free_folios_and_swap_cache(struct pfn_range *folios, int nr) { lru_add_drain(); for (int i = 0; i < nr; i++) - free_swap_cache(pages[i]); - release_pages(pages, nr); + free_swap_cache(pfn_to_page(folios[i].start)); + folios_put_refs(folios, nr); } static inline bool swap_use_vma_readahead(void)