From patchwork Fri Sep 25 20:44:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ralph Campbell X-Patchwork-Id: 1371577 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=nvidia.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=nvidia.com header.i=@nvidia.com header.a=rsa-sha256 header.s=n1 header.b=kUTBmFHS; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BykS84WpJz9sVC for ; Sat, 26 Sep 2020 06:44:56 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727727AbgIYUoz (ORCPT ); Fri, 25 Sep 2020 16:44:55 -0400 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:12613 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727519AbgIYUoy (ORCPT ); Fri, 25 Sep 2020 16:44:54 -0400 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Fri, 25 Sep 2020 13:44:40 -0700 Received: from HQMAIL111.nvidia.com (172.20.187.18) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 25 Sep 2020 20:44:49 +0000 Received: from rcampbell-dev.nvidia.com (10.124.1.5) by mail.nvidia.com (172.20.187.18) with Microsoft SMTP Server id 15.0.1473.3 via Frontend Transport; Fri, 25 Sep 2020 20:44:49 +0000 From: Ralph Campbell To: , , , CC: Dan Williams , Ira Weiny , Matthew Wilcox , Jerome Glisse , John Hubbard , Alistair Popple , Christoph Hellwig , Jason Gunthorpe , "Bharata B Rao" , Zi Yan , "Kirill A . Shutemov" , Yang Shi , Paul Mackerras , Ben Skeggs , "Andrew Morton" , Ralph Campbell Subject: [PATCH 2/2] mm: remove extra ZONE_DEVICE struct page refcount Date: Fri, 25 Sep 2020 13:44:42 -0700 Message-ID: <20200925204442.31348-3-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200925204442.31348-1-rcampbell@nvidia.com> References: <20200925204442.31348-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1601066681; bh=lY+MAo59AVccL8lf+hv6kgC9mNiDhM9kmvtwEw1vnTc=; h=From:To:CC:Subject:Date:Message-ID:X-Mailer:In-Reply-To: References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=kUTBmFHS20BaKQDy+fAJddFU9znxFQapMKyH9CHz8oW/ggxioiCrxKGvuKt4q/blX ewRla4EuRUByBUfFIScLULYcbW+cSxg+RYawUuo+FuAkxJunK8iLXshFqrY74fBmpQ dyYQK/+m1FIO7lP+67+Eqg5v+tPRjjVg+7WDPYsRG8W9N8uljapqEko7ZLw32pTisc S4mrmKO68w5u9Y1s5mKmxJvMtAsUrU/zNzEoP6CffLUxGMILdjLMGfBZmnGKLHihP5 kk7ueD2506gOcBMoqrTlJd1+ihUZ8U7pi7vmpCx43wL3ZbBfzZKNxxSDCA1zamwwL3 L0R3FbvohA4lg== Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org ZONE_DEVICE struct pages have an extra reference count that complicates the code for put_page() and several places in the kernel that need to check the reference count to see that a page is not being used (gup, compaction, migration, etc.). Clean up the code so the reference count doesn't need to be treated specially for ZONE_DEVICE. Signed-off-by: Ralph Campbell Tested-by: Bharata B Rao --- arch/powerpc/kvm/book3s_hv_uvmem.c | 2 +- drivers/gpu/drm/nouveau/nouveau_dmem.c | 2 +- include/linux/dax.h | 2 +- include/linux/memremap.h | 7 ++- include/linux/mm.h | 44 -------------- lib/test_hmm.c | 2 +- mm/gup.c | 44 -------------- mm/internal.h | 8 +++ mm/memremap.c | 82 ++++++-------------------- mm/migrate.c | 5 -- mm/page_alloc.c | 3 + mm/swap.c | 46 +++------------ 12 files changed, 44 insertions(+), 203 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 7705d5557239..e6ec98325fab 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -711,7 +711,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm) dpage = pfn_to_page(uvmem_pfn); dpage->zone_device_data = pvt; - get_page(dpage); + init_page_count(dpage); lock_page(dpage); return dpage; out_clear: diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 4e8112fde3e6..ca2e3c3edc36 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c @@ -323,7 +323,7 @@ nouveau_dmem_page_alloc_locked(struct nouveau_drm *drm) return NULL; } - get_page(page); + init_page_count(page); lock_page(page); return page; } diff --git a/include/linux/dax.h b/include/linux/dax.h index 3f78ed78d1d6..8d29f38645aa 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -240,7 +240,7 @@ static inline bool dax_mapping(struct address_space *mapping) static inline bool dax_layout_is_idle_page(struct page *page) { - return page_ref_count(page) <= 1; + return page_ref_count(page) == 0; } #endif diff --git a/include/linux/memremap.h b/include/linux/memremap.h index e5862746751b..f9224f88e4cd 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -65,9 +65,10 @@ enum memory_type { struct dev_pagemap_ops { /* - * Called once the page refcount reaches 1. (ZONE_DEVICE pages never - * reach 0 refcount unless there is a refcount bug. This allows the - * device driver to implement its own memory management.) + * Called once the page refcount reaches 0. The reference count + * should be reset to one with init_page_count(page) before reusing + * the page. This allows the device driver to implement its own + * memory management. */ void (*page_free)(struct page *page); diff --git a/include/linux/mm.h b/include/linux/mm.h index b2f370f0b420..2159c2477aa3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1092,39 +1092,6 @@ static inline bool is_zone_device_page(const struct page *page) } #endif -#ifdef CONFIG_DEV_PAGEMAP_OPS -void free_devmap_managed_page(struct page *page); -DECLARE_STATIC_KEY_FALSE(devmap_managed_key); - -static inline bool page_is_devmap_managed(struct page *page) -{ - if (!static_branch_unlikely(&devmap_managed_key)) - return false; - if (!is_zone_device_page(page)) - return false; - switch (page->pgmap->type) { - case MEMORY_DEVICE_PRIVATE: - case MEMORY_DEVICE_FS_DAX: - return true; - default: - break; - } - return false; -} - -void put_devmap_managed_page(struct page *page); - -#else /* CONFIG_DEV_PAGEMAP_OPS */ -static inline bool page_is_devmap_managed(struct page *page) -{ - return false; -} - -static inline void put_devmap_managed_page(struct page *page) -{ -} -#endif /* CONFIG_DEV_PAGEMAP_OPS */ - static inline bool is_device_private_page(const struct page *page) { return IS_ENABLED(CONFIG_DEV_PAGEMAP_OPS) && @@ -1171,17 +1138,6 @@ static inline void put_page(struct page *page) { page = compound_head(page); - /* - * For devmap managed pages we need to catch refcount transition from - * 2 to 1, when refcount reach one it means the page is free and we - * need to inform the device driver through callback. See - * include/linux/memremap.h and HMM for details. - */ - if (page_is_devmap_managed(page)) { - put_devmap_managed_page(page); - return; - } - if (put_page_testzero(page)) __put_page(page); } diff --git a/lib/test_hmm.c b/lib/test_hmm.c index e7dc3de355b7..1033b19c9c52 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -561,7 +561,7 @@ static struct page *dmirror_devmem_alloc_page(struct dmirror_device *mdevice) } dpage->zone_device_data = rpage; - get_page(dpage); + init_page_count(dpage); lock_page(dpage); return dpage; diff --git a/mm/gup.c b/mm/gup.c index e5739a1974d5..9b3e94db3a09 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -177,41 +177,6 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags) return true; } -#ifdef CONFIG_DEV_PAGEMAP_OPS -static bool __unpin_devmap_managed_user_page(struct page *page) -{ - int count, refs = 1; - - if (!page_is_devmap_managed(page)) - return false; - - if (hpage_pincount_available(page)) - hpage_pincount_sub(page, 1); - else - refs = GUP_PIN_COUNTING_BIAS; - - count = page_ref_sub_return(page, refs); - - mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED, 1); - /* - * devmap page refcounts are 1-based, rather than 0-based: if - * refcount is 1, then the page is free and the refcount is - * stable because nobody holds a reference on the page. - */ - if (count == 1) - free_devmap_managed_page(page); - else if (!count) - __put_page(page); - - return true; -} -#else -static bool __unpin_devmap_managed_user_page(struct page *page) -{ - return false; -} -#endif /* CONFIG_DEV_PAGEMAP_OPS */ - /** * unpin_user_page() - release a dma-pinned page * @page: pointer to page to be released @@ -227,15 +192,6 @@ void unpin_user_page(struct page *page) page = compound_head(page); - /* - * For devmap managed pages we need to catch refcount transition from - * GUP_PIN_COUNTING_BIAS to 1, when refcount reach one it means the - * page is free and we need to inform the device driver through - * callback. See include/linux/memremap.h and HMM for details. - */ - if (__unpin_devmap_managed_user_page(page)) - return; - if (hpage_pincount_available(page)) hpage_pincount_sub(page, 1); else diff --git a/mm/internal.h b/mm/internal.h index 10c677655912..c9de39ad5f52 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -620,4 +620,12 @@ struct migration_target_control { gfp_t gfp_mask; }; +#ifdef CONFIG_DEV_PAGEMAP_OPS +void free_zone_device_page(struct page *page); +#else +static inline void free_zone_device_page(struct page *page) +{ +} +#endif + #endif /* __MM_INTERNAL_H */ diff --git a/mm/memremap.c b/mm/memremap.c index 006dace60b1a..961e09b20543 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -12,6 +12,7 @@ #include #include #include +#include "internal.h" static DEFINE_XARRAY(pgmap_array); @@ -37,39 +38,6 @@ unsigned long memremap_compat_align(void) EXPORT_SYMBOL_GPL(memremap_compat_align); #endif -#ifdef CONFIG_DEV_PAGEMAP_OPS -DEFINE_STATIC_KEY_FALSE(devmap_managed_key); -EXPORT_SYMBOL(devmap_managed_key); -static atomic_t devmap_managed_enable; - -static void devmap_managed_enable_put(void) -{ - if (atomic_dec_and_test(&devmap_managed_enable)) - static_branch_disable(&devmap_managed_key); -} - -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) -{ - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - - if (atomic_inc_return(&devmap_managed_enable) == 1) - static_branch_enable(&devmap_managed_key); - return 0; -} -#else -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) -{ - return -EINVAL; -} -static void devmap_managed_enable_put(void) -{ -} -#endif /* CONFIG_DEV_PAGEMAP_OPS */ - static void pgmap_array_delete(struct resource *res) { xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end), @@ -90,16 +58,6 @@ static unsigned long pfn_end(struct dev_pagemap *pgmap) return (res->start + resource_size(res)) >> PAGE_SHIFT; } -static unsigned long pfn_next(unsigned long pfn) -{ - if (pfn % 1024 == 0) - cond_resched(); - return pfn + 1; -} - -#define for_each_device_pfn(pfn, map) \ - for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn)) - static void dev_pagemap_kill(struct dev_pagemap *pgmap) { if (pgmap->ops && pgmap->ops->kill) @@ -128,12 +86,10 @@ void memunmap_pages(struct dev_pagemap *pgmap) { struct resource *res = &pgmap->res; struct page *first_page; - unsigned long pfn; int nid; dev_pagemap_kill(pgmap); - for_each_device_pfn(pfn, pgmap) - put_page(pfn_to_page(pfn)); + percpu_ref_put_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap)); dev_pagemap_cleanup(pgmap); /* make sure to access a memmap that was actually initialized */ @@ -158,7 +114,6 @@ void memunmap_pages(struct dev_pagemap *pgmap) untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res)); pgmap_array_delete(res); WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n"); - devmap_managed_enable_put(); } EXPORT_SYMBOL_GPL(memunmap_pages); @@ -192,7 +147,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) .pgprot = PAGE_KERNEL, }; int error, is_ram; - bool need_devmap_managed = true; switch (pgmap->type) { case MEMORY_DEVICE_PRIVATE: @@ -217,11 +171,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) } break; case MEMORY_DEVICE_GENERIC: - need_devmap_managed = false; break; case MEMORY_DEVICE_PCI_P2PDMA: params.pgprot = pgprot_noncached(params.pgprot); - need_devmap_managed = false; break; default: WARN(1, "Invalid pgmap type %d\n", pgmap->type); @@ -245,12 +197,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) } } - if (need_devmap_managed) { - error = devmap_managed_enable_get(pgmap); - if (error) - return ERR_PTR(error); - } - conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL); if (conflict_pgmap) { WARN(1, "Conflicting mapping in same section\n"); @@ -348,7 +294,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) err_array: dev_pagemap_kill(pgmap); dev_pagemap_cleanup(pgmap); - devmap_managed_enable_put(); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(memremap_pages); @@ -443,14 +388,8 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, EXPORT_SYMBOL_GPL(get_dev_pagemap); #ifdef CONFIG_DEV_PAGEMAP_OPS -void free_devmap_managed_page(struct page *page) +static void free_device_private_page(struct page *page) { - /* notify page idle for dax */ - if (!is_device_private_page(page)) { - wake_up_var(&page->_refcount); - return; - } - /* Clear Active bit in case of parallel mark_page_accessed */ __ClearPageActive(page); __ClearPageWaiters(page); @@ -481,4 +420,19 @@ void free_devmap_managed_page(struct page *page) page->mapping = NULL; page->pgmap->ops->page_free(page); } + +void free_zone_device_page(struct page *page) +{ + switch (page->pgmap->type) { + case MEMORY_DEVICE_FS_DAX: + /* notify page idle */ + wake_up_var(&page->_refcount); + return; + case MEMORY_DEVICE_PRIVATE: + free_device_private_page(page); + return; + default: + return; + } +} #endif /* CONFIG_DEV_PAGEMAP_OPS */ diff --git a/mm/migrate.c b/mm/migrate.c index aecb1433cf3c..c51749c7cb9d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -380,11 +380,6 @@ static int expected_page_refs(struct address_space *mapping, struct page *page) { int expected_count = 1; - /* - * Device public or private pages have an extra refcount as they are - * ZONE_DEVICE pages. - */ - expected_count += is_device_private_page(page); if (mapping) expected_count += thp_nr_pages(page) + page_has_private(page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fab5e97dc9ca..397b0765de97 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6070,6 +6070,9 @@ void __ref memmap_init_zone_device(struct zone *zone, __init_single_page(page, pfn, zone_idx, nid); + /* ZONE_DEVICE pages start with a zero reference count. */ + set_page_count(page, 0); + /* * Mark page reserved as it will need to wait for onlining * phase for it to be fully associated with a zone. diff --git a/mm/swap.c b/mm/swap.c index e7bdf094f76a..769644fe70ef 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -116,12 +116,11 @@ static void __put_compound_page(struct page *page) void __put_page(struct page *page) { if (is_zone_device_page(page)) { - put_dev_pagemap(page->pgmap); - /* * The page belongs to the device that created pgmap. Do * not return it to page allocator. */ + free_zone_device_page(page); return; } @@ -848,30 +847,22 @@ void release_pages(struct page **pages, int nr) locked_pgdat = NULL; } + page = compound_head(page); if (is_huge_zero_page(page)) continue; + if (!put_page_testzero(page)) + continue; + if (is_zone_device_page(page)) { if (locked_pgdat) { spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); locked_pgdat = NULL; } - /* - * ZONE_DEVICE pages that return 'false' from - * put_devmap_managed_page() do not require special - * processing, and instead, expect a call to - * put_page_testzero(). - */ - if (page_is_devmap_managed(page)) { - put_devmap_managed_page(page); - continue; - } - } - - page = compound_head(page); - if (!put_page_testzero(page)) + free_zone_device_page(page); continue; + } if (PageCompound(page)) { if (locked_pgdat) { @@ -1151,26 +1142,3 @@ void __init swap_setup(void) * _really_ don't want to cluster much more */ } - -#ifdef CONFIG_DEV_PAGEMAP_OPS -void put_devmap_managed_page(struct page *page) -{ - int count; - - if (WARN_ON_ONCE(!page_is_devmap_managed(page))) - return; - - count = page_ref_dec_return(page); - - /* - * devmap page refcounts are 1-based, rather than 0-based: if - * refcount is 1, then the page is free and the refcount is - * stable because nobody holds a reference on the page. - */ - if (count == 1) - free_devmap_managed_page(page); - else if (!count) - __put_page(page); -} -EXPORT_SYMBOL(put_devmap_managed_page); -#endif