From patchwork Fri Nov 27 16:41:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11936765 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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 50F89C8303B for ; Fri, 27 Nov 2020 16:43:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A4BE221F7 for ; Fri, 27 Nov 2020 16:43:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="PXrPfbF/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732124AbgK0QnE (ORCPT ); Fri, 27 Nov 2020 11:43:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731686AbgK0QmH (ORCPT ); Fri, 27 Nov 2020 11:42:07 -0500 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82251C0613D1 for ; Fri, 27 Nov 2020 08:42:05 -0800 (PST) Received: by mail-wr1-x444.google.com with SMTP id u12so6231228wrt.0 for ; Fri, 27 Nov 2020 08:42:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=9N/vIVQZ5CWx0IgXYdg3dFpbuCtWMvkamJ2ufW+wr90=; b=PXrPfbF/4OJ/qafS7X9VGOgGk68xwME2tmBm79ezq1c/N5MitZuOuaeeFBbbs41BD8 9At+9Uv7XClvYz3quku79j0vnnUqdIBTDWxMq8f14jxQKtKd134NgE9C+y15xJzid7BV 96ehZMOmxDrpmqjxCVYnC8UIwDh0NrD67uvFA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=9N/vIVQZ5CWx0IgXYdg3dFpbuCtWMvkamJ2ufW+wr90=; b=CdOyJHZQEolq/tjd847BBVLvrZOPk9AOkDCvP43WwpIpH6R5XD8EcZsI5rlMaHgcrh hYOBnDhmoRKEyWpSyTR0m/BVdxIUAR63e6jRWZ0+iUhoT4nXMUKd6xx+ICcc2AymL6/s 54CHmssVCMaiU1Dm9Y9hvgGFDmfDBvHt9SfXoUy/VkunCNSkPLV9HzYpDF6oGl2Dqlje CS4P2QgKuJ1YxmShp0U/PI8j7uRE/ap+do3wijDkgZg2yrWHdnSia8SQ8mMkdU1EKXOV GsjLTL6ConNEjwef4bQDKIR+xmksDcHlUlFqsqjzxK/NcNpZvt0EpDqRDQUlD8YE2fxp /mEg== X-Gm-Message-State: AOAM531lviR0hlQLsNOHSbDaSOp1BP4yLMxGctJkVD9Wd1CmITgK6HtT RAbMzCVwz+h0AodburGwMKp0Qw== X-Google-Smtp-Source: ABdhPJxqlICPp/N/mFUK2E5mz9eed91s7W9a4LVq4PLGr+Rdm/Nn+OLHpB+Qo3oZkctQQEFBRKWpIg== X-Received: by 2002:adf:f2ce:: with SMTP id d14mr11625703wrp.94.1606495324264; Fri, 27 Nov 2020 08:42:04 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id q12sm14859078wrx.86.2020.11.27.08.42.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Nov 2020 08:42:03 -0800 (PST) From: Daniel Vetter To: DRI Development , LKML Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, Daniel Vetter , Daniel Vetter , Christoph Hellwig , Jason Gunthorpe , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Tomasz Figa , Mauro Carvalho Chehab , Andrew Morton , John Hubbard , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Jan Kara , Dan Williams Subject: [PATCH v7 05/17] mm/frame-vector: Use FOLL_LONGTERM Date: Fri, 27 Nov 2020 17:41:19 +0100 Message-Id: <20201127164131.2244124-6-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org This is used by media/videbuf2 for persistent dma mappings, not just for a single dma operation and then freed again, so needs FOLL_LONGTERM. Unfortunately current pup_locked doesn't support FOLL_LONGTERM due to locking issues. Rework the code to pull the pup path out from the mmap_sem critical section as suggested by Jason. By relying entirely on the vma checks in pin_user_pages and follow_pfn (for vm_flags and vma_is_fsdax) we can also streamline the code a lot. Note that pin_user_pages_fast is a safe replacement despite the seeming lack of checking for vma->vm_flasg & (VM_IO | VM_PFNMAP). Such ptes are marked with pte_mkspecial (which pup_fast rejects in the fastpath), and only architectures supporting that support the pin_user_pages_fast fastpath. Signed-off-by: Daniel Vetter Cc: Christoph Hellwig Cc: Jason Gunthorpe Cc: Pawel Osciak Cc: Marek Szyprowski Cc: Kyungmin Park Cc: Tomasz Figa Cc: Mauro Carvalho Chehab Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Signed-off-by: Daniel Vetter --- v2: Streamline the code and further simplify the loop checks (Jason) v5: Review from Tomasz: - fix page counting for the follow_pfn case by resetting ret - drop gup_flags paramater, now unused v6: Explain why pup_fast is safe, after discussions with John and Christoph. --- .../media/common/videobuf2/videobuf2-memops.c | 3 +- include/linux/mm.h | 2 +- mm/frame_vector.c | 53 ++++++------------- 3 files changed, 19 insertions(+), 39 deletions(-) diff --git a/drivers/media/common/videobuf2/videobuf2-memops.c b/drivers/media/common/videobuf2/videobuf2-memops.c index 6e9e05153f4e..9dd6c27162f4 100644 --- a/drivers/media/common/videobuf2/videobuf2-memops.c +++ b/drivers/media/common/videobuf2/videobuf2-memops.c @@ -40,7 +40,6 @@ struct frame_vector *vb2_create_framevec(unsigned long start, unsigned long first, last; unsigned long nr; struct frame_vector *vec; - unsigned int flags = FOLL_FORCE | FOLL_WRITE; first = start >> PAGE_SHIFT; last = (start + length - 1) >> PAGE_SHIFT; @@ -48,7 +47,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start, vec = frame_vector_create(nr); if (!vec) return ERR_PTR(-ENOMEM); - ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec); + ret = get_vaddr_frames(start & PAGE_MASK, nr, vec); if (ret < 0) goto out_destroy; /* We accept only complete set of PFNs */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 47bff16c182d..29a1941cd255 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1765,7 +1765,7 @@ struct frame_vector { struct frame_vector *frame_vector_create(unsigned int nr_frames); void frame_vector_destroy(struct frame_vector *vec); int get_vaddr_frames(unsigned long start, unsigned int nr_pfns, - unsigned int gup_flags, struct frame_vector *vec); + struct frame_vector *vec); void put_vaddr_frames(struct frame_vector *vec); int frame_vector_to_pages(struct frame_vector *vec); void frame_vector_to_pfns(struct frame_vector *vec); diff --git a/mm/frame_vector.c b/mm/frame_vector.c index 10f82d5643b6..f8c34b895c76 100644 --- a/mm/frame_vector.c +++ b/mm/frame_vector.c @@ -32,13 +32,12 @@ * This function takes care of grabbing mmap_lock as necessary. */ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, - unsigned int gup_flags, struct frame_vector *vec) + struct frame_vector *vec) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; int ret = 0; int err; - int locked; if (nr_frames == 0) return 0; @@ -48,40 +47,26 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, start = untagged_addr(start); - mmap_read_lock(mm); - locked = 1; - vma = find_vma_intersection(mm, start, start + 1); - if (!vma) { - ret = -EFAULT; - goto out; - } - - /* - * While get_vaddr_frames() could be used for transient (kernel - * controlled lifetime) pinning of memory pages all current - * users establish long term (userspace controlled lifetime) - * page pinning. Treat get_vaddr_frames() like - * get_user_pages_longterm() and disallow it for filesystem-dax - * mappings. - */ - if (vma_is_fsdax(vma)) { - ret = -EOPNOTSUPP; - goto out; - } - - if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { + ret = pin_user_pages_fast(start, nr_frames, + FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, + (struct page **)(vec->ptrs)); + if (ret > 0) { vec->got_ref = true; vec->is_pfns = false; - ret = pin_user_pages_locked(start, nr_frames, - gup_flags, (struct page **)(vec->ptrs), &locked); - goto out; + goto out_unlocked; } + mmap_read_lock(mm); vec->got_ref = false; vec->is_pfns = true; + ret = 0; do { unsigned long *nums = frame_vector_pfns(vec); + vma = find_vma_intersection(mm, start, start + 1); + if (!vma) + break; + while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) { err = follow_pfn(vma, start, &nums[ret]); if (err) { @@ -92,17 +77,13 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, start += PAGE_SIZE; ret++; } - /* - * We stop if we have enough pages or if VMA doesn't completely - * cover the tail page. - */ - if (ret >= nr_frames || start < vma->vm_end) + /* Bail out if VMA doesn't completely cover the tail page. */ + if (start < vma->vm_end) break; - vma = find_vma_intersection(mm, start, start + 1); - } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP)); + } while (ret < nr_frames); out: - if (locked) - mmap_read_unlock(mm); + mmap_read_unlock(mm); +out_unlocked: if (!ret) ret = -EFAULT; if (ret > 0)