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=-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 4EBDAC43461 for ; Thu, 15 Apr 2021 18:47:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D694E60FF0 for ; Thu, 15 Apr 2021 18:47:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D694E60FF0 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CDB126B0073; Thu, 15 Apr 2021 14:47:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C8B1B6B0074; Thu, 15 Apr 2021 14:47:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AB34B6B0075; Thu, 15 Apr 2021 14:47:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0086.hostedemail.com [216.40.44.86]) by kanga.kvack.org (Postfix) with ESMTP id 85AE66B0073 for ; Thu, 15 Apr 2021 14:47:44 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 3D0C0182D211D for ; Thu, 15 Apr 2021 18:47:44 +0000 (UTC) X-FDA: 78035485248.30.E59EA54 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) by imf09.hostedemail.com (Postfix) with ESMTP id 5481E600011E for ; Thu, 15 Apr 2021 18:47:40 +0000 (UTC) Received: by mail-yb1-f201.google.com with SMTP id t9so3448281ybd.11 for ; Thu, 15 Apr 2021 11:47:43 -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=QUApq8UPhLnVOskfaex0nbVtMhAbaCtXI1eHuCuwzK0=; b=Y24xjdSehME3uPSbOxZhgaGyOVJUE3siM4RXKAlUq2C/sPUhMInXnaOjWmiVtcmR5x StHOYh2kOi4TpmaKKY8Yw4jHJV1+TJU9hXuQ+rm8Oh+UjMGEBd9g/GmJsrgtn1gUNXZ1 1PSeZY6yAZdjJfcyrnNq70NfWNiXoLyex02LJqIwBAtbrQPIoGqkNVD4oZWVran5MCGI AqNgFpwe0onN47beUZPM/bVxZ2oMTqwTPdWJ6/8zJIDW7QLX8HnYA/a5xef4Te4jrHfe Gv6RdSc0Abx17Osl29g9KgyIVVwacoFK4LtZNsUEmvDwD9+SCmSq3qTUY/e4ktk9wEli +IsQ== 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=QUApq8UPhLnVOskfaex0nbVtMhAbaCtXI1eHuCuwzK0=; b=Fbaihftf0kvKe1im6yZQ8S09lYjXd4g0H5q/nnGDI3IwbAFX8x+m4f+algEa9ikMU9 ng/1fidckPzzWmHrTZVVuqzPl4mrzPwYWUa44Iq2vgn91ega9SJqYu45yntQ5OY41Ps3 iSep+1nZcwJCIBGtf+N3MRpryQccDLq8sUUisRMAlrnvJxiFZdvH33N1KJcpCZhx2wa6 zgcfDC6OGeEWJPVZzyjprcfvAYauVgtszR0zVBxllQCAt6kJJCxQmD8sr08PAUTwrcpL CNymvi8P9MfZ0/M1i84D14Sc9BvFpUWb/nyhtdCmeZMdslVWsobDkRVyGnHx6rHiDxuR l7zQ== X-Gm-Message-State: AOAM530murvYBFBbc7XEheA4DnjIr6gYU4QsJEJGMGSHTIV0MRQ60Bwr O+SLkMmU+6SnIKCE4j0FuK76BgzxiAkrvPVSy9UL X-Google-Smtp-Source: ABdhPJx4VajWNU1JxEuPN3PCOQjFHvibPqiEX2huiN0IADIrQFOawAtK995l4DQrP69z6mqZ6J8tB0Iph8yimDbIyExL X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:21b1:6e5c:b371:7e3]) (user=axelrasmussen job=sendgmr) by 2002:a25:b098:: with SMTP id f24mr6393018ybj.210.1618512463076; Thu, 15 Apr 2021 11:47:43 -0700 (PDT) Date: Thu, 15 Apr 2021 11:47:26 -0700 In-Reply-To: <20210415184732.3410521-1-axelrasmussen@google.com> Message-Id: <20210415184732.3410521-5-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210415184732.3410521-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.31.1.368.gbe11c130af-goog Subject: [PATCH v3 04/10] userfaultfd/shmem: support minor fault registration for shmem 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 Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 5481E600011E X-Stat-Signature: uqco7qkufikpi7yfbtjj97kuigkczzck Received-SPF: none (flex--axelrasmussen.bounces.google.com>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from="<3T4p4YA0KCFAsFw39sA4CAAw5y66y3w.u64305CF-442Dsu2.69y@flex--axelrasmussen.bounces.google.com>"; helo=mail-yb1-f201.google.com; client-ip=209.85.219.201 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618512460-440139 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: This patch allows shmem-backed VMAs to be registered for minor faults. Minor faults are appropriately relayed to userspace in the fault path, for VMAs with the relevant flag. This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed minor faults, though, so userspace doesn't yet have a way to resolve such faults. Acked-by: Peter Xu Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 6 +++--- include/uapi/linux/userfaultfd.h | 7 ++++++- mm/memory.c | 8 +++++--- mm/shmem.c | 12 +++++++++++- 4 files changed, 25 insertions(+), 8 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/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index bafbeb1a2624..159a74e9564f 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 | \ @@ -185,6 +186,9 @@ struct uffdio_api { * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults * can be intercepted (via REGISTER_MODE_MINOR) for * hugetlbfs-backed pages. + * + * UFFD_FEATURE_MINOR_SHMEM indicates the same support as + * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead. */ #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) #define UFFD_FEATURE_EVENT_FORK (1<<1) @@ -196,6 +200,7 @@ 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 4e358601c5d6..cc71a445c76c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3972,9 +3972,11 @@ 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 b72c55aa07fc..30c0bb501dc9 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1785,7 +1785,7 @@ 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: + * 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, @@ -1820,6 +1820,16 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, page = pagecache_get_page(mapping, index, FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0); + + if (page && vma && userfaultfd_minor(vma)) { + if (!xa_is_value(page)) { + unlock_page(page); + put_page(page); + } + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); + return 0; + } + if (xa_is_value(page)) { error = shmem_swapin_page(inode, index, &page, sgp, gfp, vma, fault_type); -- 2.31.1.368.gbe11c130af-goog