From patchwork Tue Apr 27 22:52:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 428089 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95353C43461 for ; Tue, 27 Apr 2021 22:54:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7623461090 for ; Tue, 27 Apr 2021 22:54:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237009AbhD0Wyt (ORCPT ); Tue, 27 Apr 2021 18:54:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239410AbhD0Wxo (ORCPT ); Tue, 27 Apr 2021 18:53:44 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BB39C061344 for ; Tue, 27 Apr 2021 15:53:00 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id d16-20020a2568100000b02904edfc7f0ea5so7140138ybc.22 for ; Tue, 27 Apr 2021 15:53:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=V7Leaw/moabGhHjT6gwS5mm4c5iU1adbxYDsfDac/3I=; b=fPfYYvYLgMpYDhjLXk449JayHfBGEDpRTb65FCc2YHjhBRFcOkMsssPipzbIJKijAB AZZL3MjWmD/Jxcc4fOWj6UzR9bMCJwpv4yVvHJO5yRlWYTgDCUIIyzxjo8rMT+e8ME+s JeshZkci5IHRj0aNOO0ZfBpKM1NBqiAuBqEWKb5bKMDod1A60hwGq41vRl0+jntZQUyR IobGa7zGK4fWHCwE3ubkkFzO1N765aG6/eI5EmaoZ4wXTfJq9WIRxMDuxKUqdoYJJpaO hH/2rvt/rXAK2LTYR5MHuUSesOCd/lkziNgiDey0uBU2JBqfcuFsxmNcYkDYJqu9SH8A DDfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=V7Leaw/moabGhHjT6gwS5mm4c5iU1adbxYDsfDac/3I=; b=ti8fkoCHotOQN53xDO7XX6jI5SHEGnqYtRlarvmrgHtYSFLiOBxOf53RDsecWGxww0 XpxhvrIJGSB2Da89PeaSqWg0KT4sIKh6P64yUpJtnSAnTEFO2/JF5VCKWqNCy9F8czRa tt2IEP8c1KUTjrfU7TJf9ufiviIowMnY1yuVcSCgJezBaScAuD1xT5V9/M7nenkeqh69 AiVy02MyPCk+ak1f4SRi98Q4D/EScnhyYM6BfSTaEWbjFrEOQIAqdWoTbUxUJcWcDqB/ 1AVlDhdJJ6p2Lf89GXo86CBbeZTfn/WjxjxwLXpu7mrl9/H/tlrGWjkWZy6mtpa39OKH ReTQ== X-Gm-Message-State: AOAM5303kD5joqpwp+/O8l3aZG0Ul39rSOfHnLOJ5RjDxe4R+M9g9bKm OfeKs/E2v0CR/QCHGYPm8yc95XH+Q50qlMudUjAO X-Google-Smtp-Source: ABdhPJzQacrsTxCdDxnMJdZVxKLTR2okvxDzpay7o8nMQZmQsa5eeVUzoPCKT3fpNyUam69MRXyfS4aQfMntiO7fxj+O X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:c423:570b:b823:c33e]) (user=axelrasmussen job=sendgmr) by 2002:a25:880f:: with SMTP id c15mr27743465ybl.373.1619563979406; Tue, 27 Apr 2021 15:52:59 -0700 (PDT) Date: Tue, 27 Apr 2021 15:52:40 -0700 In-Reply-To: <20210427225244.4326-1-axelrasmussen@google.com> Message-Id: <20210427225244.4326-7-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210427225244.4326-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.31.1.498.g6c1eba8ee3d-goog Subject: [PATCH v5 06/10] userfaultfd/shmem: modify shmem_mcopy_atomic_pte to use install_pte() From: Axel Rasmussen To: Alexander Viro , Andrea Arcangeli , Andrew Morton , Hugh Dickins , Jerome Glisse , Joe Perches , Lokesh Gidra , Mike Kravetz , Mike Rapoport , Peter Xu , Shaohua Li , Shuah Khan , Stephen Rothwell , Wang Qing Cc: linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Axel Rasmussen , Brian Geffon , "Dr . David Alan Gilbert" , Mina Almasry , Oliver Upton Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org In a previous commit, we added the mcopy_atomic_install_pte() helper. This helper does the job of setting up PTEs for an existing page, to map it into a given VMA. It deals with both the anon and shmem cases, as well as the shared and private cases. In other words, shmem_mcopy_atomic_pte() duplicates a case it already handles. So, expose it, and let shmem_mcopy_atomic_pte() use it directly, to reduce code duplication. This requires that we refactor shmem_mcopy_atomic_pte() a bit: Instead of doing accounting (shmem_recalc_inode() et al) part-way through the PTE setup, do it afterward. This frees up mcopy_atomic_install_pte() from having to care about this accounting, and means we don't need to e.g. shmem_uncharge() in the error path. A side effect is this switches shmem_mcopy_atomic_pte() to use lru_cache_add_inactive_or_unevictable() instead of just lru_cache_add(). This wrapper does some extra accounting in an exceptional case, if appropriate, so it's actually the more correct thing to use. Signed-off-by: Axel Rasmussen --- include/linux/userfaultfd_k.h | 5 ++++ mm/shmem.c | 48 +++++------------------------------ mm/userfaultfd.c | 17 +++++-------- 3 files changed, 18 insertions(+), 52 deletions(-) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 794d1538b8ba..39c094cc6641 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -53,6 +53,11 @@ enum mcopy_atomic_mode { MCOPY_ATOMIC_CONTINUE, }; +extern int mcopy_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, struct page *page, + bool newly_allocated, bool wp_copy); + extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, bool *mmap_changing, __u64 mode); diff --git a/mm/shmem.c b/mm/shmem.c index 30c0bb501dc9..37db52f45cb5 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2378,10 +2378,8 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, struct address_space *mapping = inode->i_mapping; gfp_t gfp = mapping_gfp_mask(mapping); pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); - spinlock_t *ptl; void *page_kaddr; struct page *page; - pte_t _dst_pte, *dst_pte; int ret; pgoff_t max_off; @@ -2404,9 +2402,9 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, /* fallback to copy_from_user outside mmap_lock */ if (unlikely(ret)) { *pagep = page; - shmem_inode_unacct_blocks(inode, 1); + ret = -ENOENT; /* don't free the page */ - return -ENOENT; + goto out_unacct_blocks; } } else { /* ZEROPAGE */ clear_highpage(page); @@ -2432,32 +2430,10 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, if (ret) goto out_release; - _dst_pte = mk_pte(page, dst_vma->vm_page_prot); - if (dst_vma->vm_flags & VM_WRITE) - _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); - else { - /* - * We don't set the pte dirty if the vma has no - * VM_WRITE permission, so mark the page dirty or it - * could be freed from under us. We could do it - * unconditionally before unlock_page(), but doing it - * only if VM_WRITE is not set is faster. - */ - set_page_dirty(page); - } - - dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); - - ret = -EFAULT; - max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - if (unlikely(pgoff >= max_off)) - goto out_release_unlock; - - ret = -EEXIST; - if (!pte_none(*dst_pte)) - goto out_release_unlock; - - lru_cache_add(page); + ret = mcopy_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, + page, true, false); + if (ret) + goto out_release; spin_lock_irq(&info->lock); info->alloced++; @@ -2465,21 +2441,11 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, shmem_recalc_inode(inode); spin_unlock_irq(&info->lock); - inc_mm_counter(dst_mm, mm_counter_file(page)); - page_add_file_rmap(page, false); - set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); - - /* No need to invalidate - it was non-present before */ - update_mmu_cache(dst_vma, dst_addr, dst_pte); - pte_unmap_unlock(dst_pte, ptl); + SetPageDirty(page); unlock_page(page); ret = 0; out: return ret; -out_release_unlock: - pte_unmap_unlock(dst_pte, ptl); - ClearPageDirty(page); - delete_from_page_cache(page); out_release: unlock_page(page); put_page(page); diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 51d8c0127161..3a9ddbb2dbbd 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -51,18 +51,13 @@ struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, /* * Install PTEs, to map dst_addr (within dst_vma) to page. * - * This function handles MCOPY_ATOMIC_CONTINUE (which is always file-backed), - * whether or not dst_vma is VM_SHARED. It also handles the more general - * MCOPY_ATOMIC_NORMAL case, when dst_vma is *not* VM_SHARED (it may be file - * backed, or not). - * - * Note that MCOPY_ATOMIC_NORMAL for a VM_SHARED dst_vma is handled by - * shmem_mcopy_atomic_pte instead. + * This function handles both MCOPY_ATOMIC_NORMAL and _CONTINUE for both shmem + * and anon, and for both shared and private VMAs. */ -static int mcopy_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr, struct page *page, - bool newly_allocated, bool wp_copy) +int mcopy_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, struct page *page, + bool newly_allocated, bool wp_copy) { int ret; pte_t _dst_pte, *dst_pte;