From patchwork Mon May 3 18:07:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 12236715 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 679C3C43603 for ; Mon, 3 May 2021 18:08:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33A6C61283 for ; Mon, 3 May 2021 18:08:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231717AbhECSJP (ORCPT ); Mon, 3 May 2021 14:09:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231781AbhECSJA (ORCPT ); Mon, 3 May 2021 14:09:00 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 088FDC06134D for ; Mon, 3 May 2021 11:07:55 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id v12-20020a25848c0000b02904f30b36aebfso8834741ybk.1 for ; Mon, 03 May 2021 11:07:55 -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=AiJiKYjwSKz3YxlxFSckEn8zOf3uLPV5kjYbENKZphQ=; b=Qc38F5NEAHlR4PJqurW9Fn/35siI7B5/TFr+xY4RKuarShtU6D17askUe5rIyJNlvR KIddBuYHXdKF17ADt7roESMhdAd7S6zKEA2KdFPRLm6Rig6WwmXNYPq/0XawRxxZ3s9d FHBGx7jNV4Z5SPzx7CEfXdWnVkX+JqF2JpwtAh8yt8Ba3lVPZ4jyXe4V/Wz7OVSlIsj1 0CtIh6JznDm2RSkpsFpphDNLaUXCiPpQhxp+/xrvaJuTLEQpMaaQYfgRu1q+ZPxiw5CD VuR1GYO9qkw7PjFevzYuYE0hXaFpRvRAnBFYJOcjOsKC6NNtW77JMIEMxZTPb6Ruhup3 boGg== 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=AiJiKYjwSKz3YxlxFSckEn8zOf3uLPV5kjYbENKZphQ=; b=Xcta1r9N/OgthedmuAszyLhzHmOgkJznjn7zROFIh5ecpHqB/62tKvcNrvaXJYpLXf d2PNs1rjL24KlGmZRyzA8ZusKfm611dJm50y8pWyQULyzd79hNRrFzWCJKUQSiqjRdp5 uXAQCt7zMidGpZg0pcLT+3lSAMefilgxDsoA7FNl0CY9WvnThy769rX9eXi109d4tUcs eovlascbNuOxcppuY1mNkpZPGyoKp9a8/GMClWASTQGBj9aWMDN1g4Ap7nIX30hv09Jy /ditXEzaGQ2FgE4Bj60mq+pId+cbO2iZRBkBFwkX0ROxcNwm1maxYl6h6vPI0PkH8xv/ UvFg== X-Gm-Message-State: AOAM532qSa2iGaK/OngEpc9GxisrrE86t7r5gkahaf72mNmEGEQRQaNB cBTxRF+SGzE8PFAj/SMboEKs5ZZs6TxZ/IHAQAlO X-Google-Smtp-Source: ABdhPJyRZZ1YDoRpiiiH56Kae8DUQPfQZxFN1pQ+5qUM7NThcqZKeA+2bSBX+3eoVJj15C64lUb3rVSesG8+qCAitYNf X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:3d79:e69a:a4f9:ef0]) (user=axelrasmussen job=sendgmr) by 2002:a25:cac7:: with SMTP id a190mr27666541ybg.144.1620065274199; Mon, 03 May 2021 11:07:54 -0700 (PDT) Date: Mon, 3 May 2021 11:07:33 -0700 In-Reply-To: <20210503180737.2487560-1-axelrasmussen@google.com> Message-Id: <20210503180737.2487560-7-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210503180737.2487560-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.31.1.527.g47e6f16901-goog Subject: [PATCH v6 06/10] userfaultfd/shmem: modify shmem_mfill_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 mfill_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_mfill_atomic_pte() duplicates a case it already handles. So, expose it, and let shmem_mfill_atomic_pte() use it directly, to reduce code duplication. This requires that we refactor shmem_mfill_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 mfill_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_mfill_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 Reviewed-by: Peter Xu Acked-by: Hugh Dickins --- include/linux/userfaultfd_k.h | 5 +++ mm/shmem.c | 58 ++++++++--------------------------- mm/userfaultfd.c | 17 ++++------ 3 files changed, 23 insertions(+), 57 deletions(-) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 794d1538b8ba..331d2ccf0bcc 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 mfill_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 e361f1d81c8d..2e9f56c83489 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2378,14 +2378,11 @@ int shmem_mfill_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; - ret = -ENOMEM; if (!shmem_inode_acct_block(inode, 1)) { /* * We may have got a page, returned -ENOENT triggering a retry, @@ -2396,10 +2393,11 @@ int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, put_page(*pagep); *pagep = NULL; } - goto out; + return -ENOMEM; } if (!*pagep) { + ret = -ENOMEM; page = shmem_alloc_page(gfp, info, pgoff); if (!page) goto out_unacct_blocks; @@ -2414,9 +2412,9 @@ int shmem_mfill_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); @@ -2442,32 +2440,10 @@ int shmem_mfill_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 = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, + page, true, false); + if (ret) + goto out_delete_from_cache; spin_lock_irq(&info->lock); info->alloced++; @@ -2475,27 +2451,17 @@ int shmem_mfill_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); + return 0; +out_delete_from_cache: delete_from_page_cache(page); out_release: unlock_page(page); put_page(page); out_unacct_blocks: shmem_inode_unacct_blocks(inode, 1); - goto out; + return ret; } #endif /* CONFIG_USERFAULTFD */ diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index d1ac73a0d2a9..5508f7d9e2dc 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 mfill_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 mfill_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;