From patchwork Tue Mar 2 00:01:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 12111873 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=-23.5 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, UNWANTED_LANGUAGE_BODY,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 F2D6CC433E0 for ; Tue, 2 Mar 2021 16:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A302964F0D for ; Tue, 2 Mar 2021 16:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344281AbhCBQjU (ORCPT ); Tue, 2 Mar 2021 11:39:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344291AbhCBACU (ORCPT ); Mon, 1 Mar 2021 19:02:20 -0500 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 C7381C061793 for ; Mon, 1 Mar 2021 16:01:39 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id d8so20749581ybs.11 for ; Mon, 01 Mar 2021 16:01:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=dD5XxAo1TNCxSI8SsVA5uLei0U8rDJcBWJ9lgXD0vXs=; b=PIJAd1ibfG2Fo7fK+94rkkoKAHs6uyWzEXU0ItZOrXUgPlYgEXSv0E2W+BW/YhZKVz WOK0ezQH6Np91g7US+KLcZKVjs7yBWfGga8iem45uImhklzUZnU6hrYOIvVB4NDmopgy rAseR2RbdQtkWWM8lGmGHoTY6FQFYQtxntEoh2knwImA3sKEumkFf2bppPG/C/ARmIey UEEeiLwPBKMDOFTioQIK2owcVbOFgkX9cW1IUAhp87SyNuv5zJZcuHFCHSdUKVcmT23N zMyvn7dVLBGy4DHWAv50qPPzpfax3WrbbxmsDtYcNxUglg3X8ceZ6WIcJteIPoaBvCAF 1ZAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=dD5XxAo1TNCxSI8SsVA5uLei0U8rDJcBWJ9lgXD0vXs=; b=Ba5PuJS11xqK9mcBiVjDpscVMRd3dwnoYRtGyCGj9lt3TJvBSB8ZxwlbGV4ArcvrZz /XjO7E1uGB56813/Om3Jx9oCNRllKD48KXcfMZ6phVPb3O7H6vTJTiEPgdXdcpQqA7TR APJAWjVI0x8NPblq9PXm3L/k6zjJmKQ5eKUnK/+XLaMHllPyqT0f3EO6xsvjdxSVdQ6j Gs2393g7ctrHRFZV6ANBuMnj+xBZxv2cKQ58zIWHIEIYS+8+UCT3zjJb9GIb/A/eSkAt zCqNv5umWaUErifk+PYPvWKpH1zrbD+MIoITDmNF0uEiD4NyGSRb9Eam4b9kYE3wJgLU 8sIA== X-Gm-Message-State: AOAM531045LfJ/Cei1XntxrSd0AYt8L1rhdqFSfWWNuaFZPHN3VqYvUy Z9mw3OuFPBLAYpafCkuQFprDDzaIrafUjNgq1z2T X-Google-Smtp-Source: ABdhPJxZtFs+QB3S/qudrbvoa9yAKFvT4TUnb+q/3wsKHGJHzTzmrPEC5DM75gH7P53BfzFAG7Poea900G19iILmeGd4 Sender: "axelrasmussen via sendgmr" X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:1998:8165:ca50:ab8d]) (user=axelrasmussen job=sendgmr) by 2002:a25:ac4e:: with SMTP id r14mr26659441ybd.340.1614643299058; Mon, 01 Mar 2021 16:01:39 -0800 (PST) Date: Mon, 1 Mar 2021 16:01:29 -0800 In-Reply-To: <20210302000133.272579-1-axelrasmussen@google.com> Message-Id: <20210302000133.272579-2-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210302000133.272579-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [PATCH v2 1/5] userfaultfd: support minor fault handling for shmem From: Axel Rasmussen To: Alexander Viro , Andrea Arcangeli , Andrew Morton , Hugh Dickins , Jerome Glisse , Joe Perches , Lokesh Gidra , Mike Rapoport , Peter Xu , Shaohua Li , Shuah Khan , Wang Qing Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Axel Rasmussen , Brian Geffon , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Michel Lespinasse , Mina Almasry , Oliver Upton Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Modify the userfaultfd register API to allow registering shmem VMAs in minor mode. Modify the shmem mcopy implementation to support UFFDIO_CONTINUE in order to resolve such faults. Combine the shmem mcopy handler functions into a single shmem_mcopy_atomic_pte, which takes a mode parameter. This matches how the hugetlbfs implementation is structured, and lets us remove a good chunk of boilerplate. Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 6 +-- include/linux/shmem_fs.h | 26 ++++----- include/uapi/linux/userfaultfd.h | 4 +- mm/memory.c | 8 +-- mm/shmem.c | 92 +++++++++++++++----------------- mm/userfaultfd.c | 27 +++++----- 6 files changed, 79 insertions(+), 84 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 14f92285d04f..9f3b8684cf3c 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1267,8 +1267,7 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma, } if (vm_flags & VM_UFFD_MINOR) { - /* FIXME: Add minor fault interception for shmem. */ - if (!is_vm_hugetlb_page(vma)) + if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma))) return false; } @@ -1941,7 +1940,8 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, /* report all available features and ioctls to userland */ uffdio_api.features = UFFD_API_FEATURES; #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR - uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS; + uffdio_api.features &= + ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); #endif uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index d82b6f396588..f0919c3722e7 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -9,6 +9,7 @@ #include #include #include +#include /* inode in-kernel data */ @@ -122,21 +123,16 @@ static inline bool shmem_file(struct file *file) extern bool shmem_charge(struct inode *inode, long pages); extern void shmem_uncharge(struct inode *inode, long pages); +#ifdef CONFIG_USERFAULTFD #ifdef CONFIG_SHMEM -extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr, - unsigned long src_addr, - struct page **pagep); -extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr); -#else -#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \ - src_addr, pagep) ({ BUG(); 0; }) -#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \ - dst_addr) ({ BUG(); 0; }) -#endif +int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, unsigned long src_addr, + enum mcopy_atomic_mode mode, struct page **pagep); +#else /* !CONFIG_SHMEM */ +#define shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \ + src_addr, mode, pagep) ({ BUG(); 0; }) +#endif /* CONFIG_SHMEM */ +#endif /* CONFIG_USERFAULTFD */ #endif diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index bafbeb1a2624..47d9790d863d 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -31,7 +31,8 @@ UFFD_FEATURE_MISSING_SHMEM | \ UFFD_FEATURE_SIGBUS | \ UFFD_FEATURE_THREAD_ID | \ - UFFD_FEATURE_MINOR_HUGETLBFS) + UFFD_FEATURE_MINOR_HUGETLBFS | \ + UFFD_FEATURE_MINOR_SHMEM) #define UFFD_API_IOCTLS \ ((__u64)1 << _UFFDIO_REGISTER | \ (__u64)1 << _UFFDIO_UNREGISTER | \ @@ -196,6 +197,7 @@ struct uffdio_api { #define UFFD_FEATURE_SIGBUS (1<<7) #define UFFD_FEATURE_THREAD_ID (1<<8) #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9) +#define UFFD_FEATURE_MINOR_SHMEM (1<<10) __u64 features; __u64 ioctls; diff --git a/mm/memory.c b/mm/memory.c index c8e357627318..a1e5ff55027e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3929,9 +3929,11 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf) * something). */ if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { - ret = do_fault_around(vmf); - if (ret) - return ret; + if (likely(!userfaultfd_minor(vmf->vma))) { + ret = do_fault_around(vmf); + if (ret) + return ret; + } } ret = __do_fault(vmf); diff --git a/mm/shmem.c b/mm/shmem.c index b2db4ed0fbc7..6f81259fabb3 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -77,7 +77,6 @@ static struct vfsmount *shm_mnt; #include #include #include -#include #include #include @@ -1785,8 +1784,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, * vm. If we swap it in we mark it dirty since we also free the swap * entry since a page cannot live in both the swap and page cache. * - * vmf and fault_type are only supplied by shmem_fault: - * otherwise they are NULL. + * vma, vmf, and fault_type are only supplied by shmem_fault: otherwise they + * are NULL. */ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, gfp_t gfp, @@ -1830,6 +1829,12 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, return error; } + if (page && vma && userfaultfd_minor(vma)) { + unlock_page(page); + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); + return 0; + } + if (page) hindex = page->index; if (page && sgp == SGP_WRITE) @@ -2354,14 +2359,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode return inode; } -static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr, - unsigned long src_addr, - bool zeropage, - struct page **pagep) +int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, unsigned long src_addr, + enum mcopy_atomic_mode mode, struct page **pagep) { + bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); struct inode *inode = file_inode(dst_vma->vm_file); struct shmem_inode_info *info = SHMEM_I(inode); struct address_space *mapping = inode->i_mapping; @@ -2378,12 +2381,17 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!shmem_inode_acct_block(inode, 1)) goto out; - if (!*pagep) { + if (is_continue) { + ret = -EFAULT; + page = find_lock_page(mapping, pgoff); + if (!page) + goto out_unacct_blocks; + } else if (!*pagep) { page = shmem_alloc_page(gfp, info, pgoff); if (!page) goto out_unacct_blocks; - if (!zeropage) { /* mcopy_atomic */ + if (mode == MCOPY_ATOMIC_NORMAL) { /* mcopy_atomic */ page_kaddr = kmap_atomic(page); ret = copy_from_user(page_kaddr, (const void __user *)src_addr, @@ -2397,7 +2405,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, /* don't free the page */ return -ENOENT; } - } else { /* mfill_zeropage_atomic */ + } else { /* zeropage */ clear_highpage(page); } } else { @@ -2405,10 +2413,13 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, *pagep = NULL; } - VM_BUG_ON(PageLocked(page) || PageSwapBacked(page)); - __SetPageLocked(page); - __SetPageSwapBacked(page); - __SetPageUptodate(page); + if (!is_continue) { + VM_BUG_ON(PageSwapBacked(page)); + VM_BUG_ON(PageLocked(page)); + __SetPageLocked(page); + __SetPageSwapBacked(page); + __SetPageUptodate(page); + } ret = -EFAULT; offset = linear_page_index(dst_vma, dst_addr); @@ -2416,10 +2427,13 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (unlikely(offset >= max_off)) goto out_release; - ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, - gfp & GFP_RECLAIM_MASK, dst_mm); - if (ret) - goto out_release; + /* If page wasn't already in the page cache, add it. */ + if (!is_continue) { + ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, + gfp & GFP_RECLAIM_MASK, dst_mm); + if (ret) + goto out_release; + } _dst_pte = mk_pte(page, dst_vma->vm_page_prot); if (dst_vma->vm_flags & VM_WRITE) @@ -2446,13 +2460,15 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!pte_none(*dst_pte)) goto out_release_unlock; - lru_cache_add(page); + if (!is_continue) { + 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); + 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); @@ -2477,28 +2493,6 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, goto out; } -int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr, - unsigned long src_addr, - struct page **pagep) -{ - return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, - dst_addr, src_addr, false, pagep); -} - -int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr) -{ - struct page *page = NULL; - - return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, - dst_addr, 0, true, &page); -} - #ifdef CONFIG_TMPFS static const struct inode_operations shmem_symlink_inode_operations; static const struct inode_operations shmem_short_symlink_operations; diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index ce6cb4760d2c..6cd7ab531aec 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -415,7 +415,7 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, unsigned long dst_addr, unsigned long src_addr, struct page **page, - bool zeropage, + enum mcopy_atomic_mode mode, bool wp_copy) { ssize_t err; @@ -431,22 +431,24 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, * and not in the radix tree. */ if (!(dst_vma->vm_flags & VM_SHARED)) { - if (!zeropage) + switch (mode) { + case MCOPY_ATOMIC_NORMAL: err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page, wp_copy); - else + break; + case MCOPY_ATOMIC_ZEROPAGE: err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); + break; + case MCOPY_ATOMIC_CONTINUE: + err = -EINVAL; + break; + } } else { VM_WARN_ON_ONCE(wp_copy); - if (!zeropage) - err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, - dst_vma, dst_addr, - src_addr, page); - else - err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, - dst_vma, dst_addr); + err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, + src_addr, mode, page); } return err; @@ -467,7 +469,6 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, long copied; struct page *page; bool wp_copy; - bool zeropage = (mcopy_mode == MCOPY_ATOMIC_ZEROPAGE); /* * Sanitize the command parameters: @@ -530,7 +531,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; - if (mcopy_mode == MCOPY_ATOMIC_CONTINUE) + if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) goto out_unlock; /* @@ -578,7 +579,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, BUG_ON(pmd_trans_huge(*dst_pmd)); err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, - src_addr, &page, zeropage, wp_copy); + src_addr, &page, mcopy_mode, wp_copy); cond_resched(); if (unlikely(err == -ENOENT)) {