From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBF51C433DB for ; Sat, 13 Mar 2021 05:07:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8578D64F76 for ; Sat, 13 Mar 2021 05:07:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8578D64F76 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 265246B0078; Sat, 13 Mar 2021 00:07:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 23BF66B007B; Sat, 13 Mar 2021 00:07:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 103A96B007D; Sat, 13 Mar 2021 00:07:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0156.hostedemail.com [216.40.44.156]) by kanga.kvack.org (Postfix) with ESMTP id E55536B0078 for ; Sat, 13 Mar 2021 00:07:28 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A96F21843913B for ; Sat, 13 Mar 2021 05:07:28 +0000 (UTC) X-FDA: 77913667776.04.5EB56DE Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf19.hostedemail.com (Postfix) with ESMTP id 3BB4E90009E8 for ; Sat, 13 Mar 2021 05:07:27 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id B2A4964F8C; Sat, 13 Mar 2021 05:07:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1615612047; bh=Inc2Z/H5sEdS6I+zvm4fjbAVUEjfa21iVmt+f+z76zw=; h=Date:From:To:Subject:In-Reply-To:From; b=Mqpaiqcq0jly/dei3ErHlM90UmRl6dX8OPg8YCGb8BAmWXHjYsbWXn6K18zMZj/6P ieqwoYJSXMgn8QuHWeInwS1FyqGWYMsd4x8UvThWf9vFjcFXQBRh0UV/QnAHiCYqmj OIHR8qPjW4P/eum3qKUrmLlYt2KfMnVX72MfTQ5E= Date: Fri, 12 Mar 2021 21:07:26 -0800 From: Andrew Morton To: aarcange@redhat.com, adobriyan@gmail.com, airlied@linux.ie, akpm@linux-foundation.org, daniel@ffwll.ch, david@gibson.dropbear.id.au, galpress@amazon.com, hch@lst.de, jack@suse.cz, jannh@google.com, jgg@ziepe.ca, kirill@shutemov.name, ktkhai@virtuozzo.com, linmiaohe@huawei.com, linux-graphics-maintainer@vmware.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, peterx@redhat.com, rppt@linux.vnet.ibm.com, sroland@vmware.com, torvalds@linux-foundation.org, willy@infradead.org, wzam@amazon.com Subject: [patch 08/29] mm: introduce page_needs_cow_for_dma() for deciding whether cow Message-ID: <20210313050726.2Cr09FU7B%akpm@linux-foundation.org> In-Reply-To: <20210312210632.9b7d62973d72a56fb13c7a03@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Stat-Signature: 8mtmfoxqmjfmdmch5m3d1f1x8te845ez X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3BB4E90009E8 Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf19; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615612047-913028 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: From: Peter Xu Subject: mm: introduce page_needs_cow_for_dma() for deciding whether cow We've got quite a few places (pte, pmd, pud) that explicitly checked against whether we should break the cow right now during fork(). It's easier to provide a helper, especially before we work the same thing on hugetlbfs. Since we'll reference is_cow_mapping() in mm.h, move it there too. Actually it suites mm.h more since internal.h is mm/ only, but mm.h is exported to the whole kernel. With that we should expect another patch to use is_cow_mapping() whenever we can across the kernel since we do use it quite a lot but it's always done with raw code against VM_* flags. Link: https://lkml.kernel.org/r/20210217233547.93892-4-peterx@redhat.com Signed-off-by: Peter Xu Reviewed-by: Jason Gunthorpe Cc: Alexey Dobriyan Cc: Andrea Arcangeli Cc: Christoph Hellwig Cc: Daniel Vetter Cc: David Airlie Cc: David Gibson Cc: Gal Pressman Cc: Jan Kara Cc: Jann Horn Cc: Kirill Shutemov Cc: Kirill Tkhai Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport Cc: Roland Scheidegger Cc: VMware Graphics Cc: Wei Zhang Signed-off-by: Andrew Morton --- include/linux/mm.h | 21 +++++++++++++++++++++ mm/huge_memory.c | 8 ++------ mm/internal.h | 5 ----- mm/memory.c | 8 +------- 4 files changed, 24 insertions(+), 18 deletions(-) --- a/include/linux/mm.h~mm-introduce-page_needs_cow_for_dma-for-deciding-whether-cow +++ a/include/linux/mm.h @@ -1300,6 +1300,27 @@ static inline bool page_maybe_dma_pinned GUP_PIN_COUNTING_BIAS; } +static inline bool is_cow_mapping(vm_flags_t flags) +{ + return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; +} + +/* + * This should most likely only be called during fork() to see whether we + * should break the cow immediately for a page on the src mm. + */ +static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma, + struct page *page) +{ + if (!is_cow_mapping(vma->vm_flags)) + return false; + + if (!atomic_read(&vma->vm_mm->has_pinned)) + return false; + + return page_maybe_dma_pinned(page); +} + #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) #define SECTION_IN_PAGE_FLAGS #endif --- a/mm/huge_memory.c~mm-introduce-page_needs_cow_for_dma-for-deciding-whether-cow +++ a/mm/huge_memory.c @@ -1100,9 +1100,7 @@ int copy_huge_pmd(struct mm_struct *dst_ * best effort that the pinned pages won't be replaced by another * random page during the coming copy-on-write. */ - if (unlikely(is_cow_mapping(vma->vm_flags) && - atomic_read(&src_mm->has_pinned) && - page_maybe_dma_pinned(src_page))) { + if (unlikely(page_needs_cow_for_dma(vma, src_page))) { pte_free(dst_mm, pgtable); spin_unlock(src_ptl); spin_unlock(dst_ptl); @@ -1214,9 +1212,7 @@ int copy_huge_pud(struct mm_struct *dst_ } /* Please refer to comments in copy_huge_pmd() */ - if (unlikely(is_cow_mapping(vma->vm_flags) && - atomic_read(&src_mm->has_pinned) && - page_maybe_dma_pinned(pud_page(pud)))) { + if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) { spin_unlock(src_ptl); spin_unlock(dst_ptl); __split_huge_pud(vma, src_pud, addr); --- a/mm/internal.h~mm-introduce-page_needs_cow_for_dma-for-deciding-whether-cow +++ a/mm/internal.h @@ -296,11 +296,6 @@ static inline unsigned int buddy_order(s */ #define buddy_order_unsafe(page) READ_ONCE(page_private(page)) -static inline bool is_cow_mapping(vm_flags_t flags) -{ - return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; -} - /* * These three helpers classifies VMAs for virtual memory accounting. */ --- a/mm/memory.c~mm-introduce-page_needs_cow_for_dma-for-deciding-whether-cow +++ a/mm/memory.c @@ -809,12 +809,8 @@ copy_present_page(struct vm_area_struct pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, struct page **prealloc, pte_t pte, struct page *page) { - struct mm_struct *src_mm = src_vma->vm_mm; struct page *new_page; - if (!is_cow_mapping(src_vma->vm_flags)) - return 1; - /* * What we want to do is to check whether this page may * have been pinned by the parent process. If so, @@ -828,9 +824,7 @@ copy_present_page(struct vm_area_struct * the page count. That might give false positives for * for pinning, but it will work correctly. */ - if (likely(!atomic_read(&src_mm->has_pinned))) - return 1; - if (likely(!page_maybe_dma_pinned(page))) + if (likely(!page_needs_cow_for_dma(src_vma, page))) return 1; new_page = *prealloc; _