From patchwork Tue Apr 13 05:17:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 420435 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=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 0D4B6C4361B for ; Tue, 13 Apr 2021 05:17:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E32826109E for ; Tue, 13 Apr 2021 05:17:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245199AbhDMFSE (ORCPT ); Tue, 13 Apr 2021 01:18:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50858 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344516AbhDMFSB (ORCPT ); Tue, 13 Apr 2021 01:18:01 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25F40C06138D for ; Mon, 12 Apr 2021 22:17:42 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id u5so10402266qkj.10 for ; Mon, 12 Apr 2021 22:17:42 -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=Zgnf19a0ZqBaTaEBX8AKF87dozcAw085CXjJ1xc2G4c=; b=rqmxGiY4BnZEcWcCJ+Y4vbbSqxqZkFX6FuLF06wYSiqiRFj2LBTS8LLSDpXxq7lMBQ o1/mdFqL/Uz3+JOkn0Jue9LNkOwwljV5BRnIvnUl9KGbag7eHngfvvGNmTLx+nXlnDTd 7VUCIt7IyXYtkNy8DDa9eov2tj+2HYt/8dtNrZeOHwpUwFGGGjXLANcpQIfhtD/pKprM Yfuj+k1QdImYGkVGyfGiN7bGeOflMKLmMbxIO07eeZF8SAq6m076BaCNiz1tjxPpMrGv RZmBTppvtn/efQKL/L55N+t7JEdEjC9eWgKjygFvdeh8P6btLSwC2PQefmW+cw3qQsAr agYw== 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=Zgnf19a0ZqBaTaEBX8AKF87dozcAw085CXjJ1xc2G4c=; b=aEPOTY76V5GEPD7lckY5MkaaO5B5RHbfbhiuBqJJzs+/RRc3txsI9E34CZp4UtposA kBW01WA4gvqWt9rrz4r1HitsIxmJ0bHVB0GwmXpThCoUOnOmIq0Lk2IgfbuAeRYV3HuL ap9gaOmRm5W/UvE+d26r1JJ8DI9aMpkjvjbnWCzTidoK98l9HQXudWkqUFB1FI30ohGb p4IaUGzWj0CJJGcBoVbBz1P+Mo2Y7gCGV6B+e8AcXO49BZ60nBl2V7YoDEXvfGFGaF5+ Y0DVjWYb7i8kewZGZEh5Dai0P4ahbW+DzcigXEmDfFamCPx4l5J7bbGrbpvGeER1YdrI HUzA== X-Gm-Message-State: AOAM533xyj9hxjNxly5ZtajMM0WIepDfFJQ12alJG+ztGj/MyseGMjs7 v6Msx4cOUSu5WtB5P+qR242WkC/QFqeUu7ZxNCeS X-Google-Smtp-Source: ABdhPJyql4cAl964Q5k7K3SfAR0oDzEdEWKdoNew6yg0Gt+a+L3rIdX6M21mQJNnFlN9UAkKjIzHIO4lAPEqRgyC0Dyr X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:d508:eee5:2d57:3e32]) (user=axelrasmussen job=sendgmr) by 2002:a0c:ff48:: with SMTP id y8mr31802165qvt.8.1618291061296; Mon, 12 Apr 2021 22:17:41 -0700 (PDT) Date: Mon, 12 Apr 2021 22:17:21 -0700 In-Reply-To: <20210413051721.2896915-1-axelrasmussen@google.com> Message-Id: <20210413051721.2896915-10-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210413051721.2896915-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.31.1.295.g9ea45b61b8-goog Subject: [PATCH v2 9/9] userfaultfd/shmem: modify shmem_mcopy_atomic_pte to use install_ptes 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_ptes() 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 beforehand. This frees up mcopy_atomic_install_ptes() from having to care about this accounting, but it does mean we need to clean it up if we get a failure afterwards (shmem_uncharge()). We can *almost* use shmem_charge() to do this, reducing code duplication. But, it does `inode->i_mapping->nrpages++`, which would double-count since shmem_add_to_page_cache() also does this. Signed-off-by: Axel Rasmussen --- include/linux/userfaultfd_k.h | 5 ++++ mm/shmem.c | 52 +++++++---------------------------- mm/userfaultfd.c | 25 ++++++++--------- 3 files changed, 27 insertions(+), 55 deletions(-) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 794d1538b8ba..3e20bfa9ef80 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_ptes(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 3f48cb5e8404..9b12298405a4 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2376,10 +2376,8 @@ 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; @@ -2389,8 +2387,10 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, if (!*pagep) { page = shmem_alloc_page(gfp, info, pgoff); - if (!page) - goto out_unacct_blocks; + if (!page) { + shmem_inode_unacct_blocks(inode, 1); + goto out; + } if (!zeropage) { /* COPY */ page_kaddr = kmap_atomic(page); @@ -2430,59 +2430,27 @@ 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); - spin_lock_irq(&info->lock); info->alloced++; inode->i_blocks += BLOCKS_PER_PAGE; 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); + ret = mcopy_atomic_install_ptes(dst_mm, dst_pmd, dst_vma, dst_addr, + page, true, false); + if (ret) + goto out_release_uncharge; - /* No need to invalidate - it was non-present before */ - update_mmu_cache(dst_vma, dst_addr, dst_pte); - pte_unmap_unlock(dst_pte, ptl); unlock_page(page); ret = 0; out: return ret; -out_release_unlock: - pte_unmap_unlock(dst_pte, ptl); - ClearPageDirty(page); +out_release_uncharge: delete_from_page_cache(page); + shmem_uncharge(inode, 1); out_release: unlock_page(page); put_page(page); -out_unacct_blocks: - shmem_inode_unacct_blocks(inode, 1); goto out; } #endif /* CONFIG_USERFAULTFD */ diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 8df0438f5d6a..3f73ba0b99f0 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_ptes(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_ptes(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; @@ -116,8 +111,12 @@ static int mcopy_atomic_install_ptes(struct mm_struct *dst_mm, pmd_t *dst_pmd, else page_add_new_anon_rmap(page, dst_vma, dst_addr, false); - if (newly_allocated) - lru_cache_add_inactive_or_unevictable(page, dst_vma); + if (newly_allocated) { + if (vma_is_shmem(dst_vma) && vm_shared) + lru_cache_add(page); + else + lru_cache_add_inactive_or_unevictable(page, dst_vma); + } set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);