From patchwork Sun Sep 4 02:17:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 12965109 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 336DD1FC3 for ; Sun, 4 Sep 2022 02:17:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662257836; x=1693793836; h=subject:from:to:cc:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=s7cUPCFRfEM51i7BRJG+0ccdu8jS149l2Tkf0+0JoZ4=; b=NKd3oshaX7nU6kA7ROgyuXGspn5ysv/Ugla0EuJzd0zDXeM5yqLv+oIi sWP28qsbSQNjxp2qdttc3giakYe4NFsXsfazJlnP2P+aYZuBuVeNdRejM SuPQH5dJQo0yAoQgtUXPnZHwC1PZ7gr06CoHxVNDKMWVaBXJGJxAGu4hp lWpEGyKc38rsOS65L/mhcODfcHwAxJLcSKhvNPSP26duhavy/O2e5x7iR ymwUzTDBi0ARdd6rlLFjY+vHUbO5BPfKs6IXgrCdiWIAEQUrf7X46LhNG uelMJHgZNCTz+tqSflADHWUsq1X2OQEeW/TwSGe6d7rjEKrY7VKT71sRR Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10459"; a="297501720" X-IronPort-AV: E=Sophos;i="5.93,288,1654585200"; d="scan'208";a="297501720" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Sep 2022 19:17:15 -0700 X-IronPort-AV: E=Sophos;i="5.93,288,1654585200"; d="scan'208";a="609343164" Received: from pg4-mobl3.amr.corp.intel.com (HELO dwillia2-xfh.jf.intel.com) ([10.212.132.198]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Sep 2022 19:17:15 -0700 Subject: [PATCH 13/13] mm/gup: Drop DAX pgmap accounting From: Dan Williams To: akpm@linux-foundation.org Cc: Matthew Wilcox , Jan Kara , "Darrick J. Wong" , Christoph Hellwig , John Hubbard , Jason Gunthorpe , linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org Date: Sat, 03 Sep 2022 19:17:15 -0700 Message-ID: <166225783530.2351842.9198292974545499645.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <166225775968.2351842.11156458342486082012.stgit@dwillia2-xfh.jf.intel.com> References: <166225775968.2351842.11156458342486082012.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Now that pgmap accounting is handled at map time, it can be dropped from gup time. A hurdle still remains that filesystem-DAX huge pages are not compound pages which still requires infrastructure like __gup_device_huge_p{m,u}d() to stick around. Additionally, ZONE_DEVICE pages with this change are still not suitable to be returned from vm_normal_page(), so this cleanup is limited to deleting pgmap reference manipulation. This is an incremental step on the path to removing pte_devmap() altogether. Note that follow_pmd_devmap() can be deleted entirely since a few additions of pmd_devmap() allows the transparent huge page path to be reused. Cc: Matthew Wilcox Cc: Jan Kara Cc: "Darrick J. Wong" Cc: Christoph Hellwig Cc: John Hubbard Reported-by: Jason Gunthorpe Signed-off-by: Dan Williams --- include/linux/huge_mm.h | 12 +------ mm/gup.c | 83 +++++++++++------------------------------------ mm/huge_memory.c | 54 +------------------------------ 3 files changed, 22 insertions(+), 127 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index de73f5a16252..b8ed373c6090 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -263,10 +263,8 @@ static inline bool folio_test_pmd_mappable(struct folio *folio) return folio_order(folio) >= HPAGE_PMD_ORDER; } -struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, int flags, struct dev_pagemap **pgmap); struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, int flags, struct dev_pagemap **pgmap); + pud_t *pud, int flags); vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf); @@ -418,14 +416,8 @@ static inline void mm_put_huge_zero_page(struct mm_struct *mm) return; } -static inline struct page *follow_devmap_pmd(struct vm_area_struct *vma, - unsigned long addr, pmd_t *pmd, int flags, struct dev_pagemap **pgmap) -{ - return NULL; -} - static inline struct page *follow_devmap_pud(struct vm_area_struct *vma, - unsigned long addr, pud_t *pud, int flags, struct dev_pagemap **pgmap) + unsigned long addr, pud_t *pud, int flags) { return NULL; } diff --git a/mm/gup.c b/mm/gup.c index 67dfffe97917..3832edd27dfd 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -25,7 +25,6 @@ #include "internal.h" struct follow_page_context { - struct dev_pagemap *pgmap; unsigned int page_mask; }; @@ -490,8 +489,7 @@ static inline bool can_follow_write_pte(pte_t pte, unsigned int flags) } static struct page *follow_page_pte(struct vm_area_struct *vma, - unsigned long address, pmd_t *pmd, unsigned int flags, - struct dev_pagemap **pgmap) + unsigned long address, pmd_t *pmd, unsigned int flags) { struct mm_struct *mm = vma->vm_mm; struct page *page; @@ -535,17 +533,13 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, } page = vm_normal_page(vma, address, pte); - if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) { + if (!page && pte_devmap(pte)) { /* - * Only return device mapping pages in the FOLL_GET or FOLL_PIN - * case since they are only valid while holding the pgmap - * reference. + * ZONE_DEVICE pages are not yet treated as vm_normal_page() + * instances, with respect to mapcount and compound-page + * metadata */ - *pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap); - if (*pgmap) - page = pte_page(pte); - else - goto no_page; + page = pte_page(pte); } else if (unlikely(!page)) { if (flags & FOLL_DUMP) { /* Avoid special (like zero) pages in core dumps */ @@ -663,15 +657,8 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, return no_page_table(vma, flags); goto retry; } - if (pmd_devmap(pmdval)) { - ptl = pmd_lock(mm, pmd); - page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap); - spin_unlock(ptl); - if (page) - return page; - } - if (likely(!pmd_trans_huge(pmdval))) - return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); + if (likely(!(pmd_trans_huge(pmdval) || pmd_devmap(pmdval)))) + return follow_page_pte(vma, address, pmd, flags); if ((flags & FOLL_NUMA) && pmd_protnone(pmdval)) return no_page_table(vma, flags); @@ -689,9 +676,9 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, pmd_migration_entry_wait(mm, pmd); goto retry_locked; } - if (unlikely(!pmd_trans_huge(*pmd))) { + if (unlikely(!(pmd_trans_huge(*pmd) || pmd_devmap(pmdval)))) { spin_unlock(ptl); - return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); + return follow_page_pte(vma, address, pmd, flags); } if (flags & FOLL_SPLIT_PMD) { int ret; @@ -709,7 +696,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, } return ret ? ERR_PTR(ret) : - follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); + follow_page_pte(vma, address, pmd, flags); } page = follow_trans_huge_pmd(vma, address, pmd, flags); spin_unlock(ptl); @@ -746,7 +733,7 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma, } if (pud_devmap(*pud)) { ptl = pud_lock(mm, pud); - page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap); + page = follow_devmap_pud(vma, address, pud, flags); spin_unlock(ptl); if (page) return page; @@ -793,9 +780,6 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, * * @flags can have FOLL_ flags set, defined in * - * When getting pages from ZONE_DEVICE memory, the @ctx->pgmap caches - * the device's dev_pagemap metadata to avoid repeating expensive lookups. - * * When getting an anonymous page and the caller has to trigger unsharing * of a shared anonymous page first, -EMLINK is returned. The caller should * trigger a fault with FAULT_FLAG_UNSHARE set. Note that unsharing is only @@ -850,7 +834,7 @@ static struct page *follow_page_mask(struct vm_area_struct *vma, struct page *follow_page(struct vm_area_struct *vma, unsigned long address, unsigned int foll_flags) { - struct follow_page_context ctx = { NULL }; + struct follow_page_context ctx = { 0 }; struct page *page; if (vma_is_secretmem(vma)) @@ -860,8 +844,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, return NULL; page = follow_page_mask(vma, address, foll_flags, &ctx); - if (ctx.pgmap) - put_dev_pagemap(ctx.pgmap); return page; } @@ -1121,7 +1103,7 @@ static long __get_user_pages(struct mm_struct *mm, { long ret = 0, i = 0; struct vm_area_struct *vma = NULL; - struct follow_page_context ctx = { NULL }; + struct follow_page_context ctx = { 0 }; if (!nr_pages) return 0; @@ -1244,8 +1226,6 @@ static long __get_user_pages(struct mm_struct *mm, nr_pages -= page_increm; } while (nr_pages); out: - if (ctx.pgmap) - put_dev_pagemap(ctx.pgmap); return i ? i : ret; } @@ -2325,9 +2305,8 @@ static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start, static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) { - struct dev_pagemap *pgmap = NULL; - int nr_start = *nr, ret = 0; pte_t *ptep, *ptem; + int ret = 0; ptem = ptep = pte_offset_map(&pmd, addr); do { @@ -2348,12 +2327,6 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, if (pte_devmap(pte)) { if (unlikely(flags & FOLL_LONGTERM)) goto pte_unmap; - - pgmap = get_dev_pagemap(pte_pfn(pte), pgmap); - if (unlikely(!pgmap)) { - undo_dev_pagemap(nr, nr_start, flags, pages); - goto pte_unmap; - } } else if (pte_special(pte)) goto pte_unmap; @@ -2400,8 +2373,6 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, ret = 1; pte_unmap: - if (pgmap) - put_dev_pagemap(pgmap); pte_unmap(ptem); return ret; } @@ -2428,28 +2399,17 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) { - int nr_start = *nr; - struct dev_pagemap *pgmap = NULL; - do { struct page *page = pfn_to_page(pfn); - pgmap = get_dev_pagemap(pfn, pgmap); - if (unlikely(!pgmap)) { - undo_dev_pagemap(nr, nr_start, flags, pages); - break; - } SetPageReferenced(page); pages[*nr] = page; - if (unlikely(!try_grab_page(page, flags))) { - undo_dev_pagemap(nr, nr_start, flags, pages); + if (unlikely(!try_grab_page(page, flags))) break; - } (*nr)++; pfn++; } while (addr += PAGE_SIZE, addr != end); - put_dev_pagemap(pgmap); return addr == end; } @@ -2458,16 +2418,14 @@ static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, struct page **pages, int *nr) { unsigned long fault_pfn; - int nr_start = *nr; fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr)) return 0; - if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) { - undo_dev_pagemap(nr, nr_start, flags, pages); + if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) return 0; - } + return 1; } @@ -2476,16 +2434,13 @@ static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, struct page **pages, int *nr) { unsigned long fault_pfn; - int nr_start = *nr; fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr)) return 0; - if (unlikely(pud_val(orig) != pud_val(*pudp))) { - undo_dev_pagemap(nr, nr_start, flags, pages); + if (unlikely(pud_val(orig) != pud_val(*pudp))) return 0; - } return 1; } #else diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8a7c1b344abe..ef68296f2158 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1031,55 +1031,6 @@ static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, update_mmu_cache_pmd(vma, addr, pmd); } -struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, - pmd_t *pmd, int flags, struct dev_pagemap **pgmap) -{ - unsigned long pfn = pmd_pfn(*pmd); - struct mm_struct *mm = vma->vm_mm; - struct page *page; - - assert_spin_locked(pmd_lockptr(mm, pmd)); - - /* - * When we COW a devmap PMD entry, we split it into PTEs, so we should - * not be in this function with `flags & FOLL_COW` set. - */ - WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); - - /* FOLL_GET and FOLL_PIN are mutually exclusive. */ - if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == - (FOLL_PIN | FOLL_GET))) - return NULL; - - if (flags & FOLL_WRITE && !pmd_write(*pmd)) - return NULL; - - if (pmd_present(*pmd) && pmd_devmap(*pmd)) - /* pass */; - else - return NULL; - - if (flags & FOLL_TOUCH) - touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); - - /* - * device mapped pages can only be returned if the - * caller will manage the page reference count. - */ - if (!(flags & (FOLL_GET | FOLL_PIN))) - return ERR_PTR(-EEXIST); - - pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; - *pgmap = get_dev_pagemap(pfn, *pgmap); - if (!*pgmap) - return ERR_PTR(-EFAULT); - page = pfn_to_page(pfn); - if (!try_grab_page(page, flags)) - page = ERR_PTR(-ENOMEM); - - return page; -} - int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) @@ -1196,7 +1147,7 @@ static void touch_pud(struct vm_area_struct *vma, unsigned long addr, } struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, - pud_t *pud, int flags, struct dev_pagemap **pgmap) + pud_t *pud, int flags) { unsigned long pfn = pud_pfn(*pud); struct mm_struct *mm = vma->vm_mm; @@ -1230,9 +1181,6 @@ struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, return ERR_PTR(-EEXIST); pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; - *pgmap = get_dev_pagemap(pfn, *pgmap); - if (!*pgmap) - return ERR_PTR(-EFAULT); page = pfn_to_page(pfn); if (!try_grab_page(page, flags)) page = ERR_PTR(-ENOMEM);