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=-10.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 4BDD2C43381 for ; Wed, 27 Feb 2019 03:54:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EF5A20C01 for ; Wed, 27 Feb 2019 03:54:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="H7+eMG8Z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729640AbfB0Dyz (ORCPT ); Tue, 26 Feb 2019 22:54:55 -0500 Received: from mail-pf1-f201.google.com ([209.85.210.201]:41026 "EHLO mail-pf1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729129AbfB0Dyy (ORCPT ); Tue, 26 Feb 2019 22:54:54 -0500 Received: by mail-pf1-f201.google.com with SMTP id z1so12228461pfz.8 for ; Tue, 26 Feb 2019 19:54:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=baxX1S5LtzfmqzAc72hpJ9BN2ZK/N6upcf+SaQYT9NE=; b=H7+eMG8ZA+v74XjzyzM6+KITVbJ6KK1i8VEz0BpZZaLGJgUdiPXnPd1EDEUuycCsJp EZjhK0tQFpeoWNcZ2Wq1CZFFJCW8T5uGW9Z89a2S63u7RvNqfmC3MwzNzVJFNTclY7gr 2MfG5bgxZr9xLo9JMwZNIup9SWhiM48jLyyAgxjf0UmO5wcME2LCVDSr8k6AgOev9789 A8THemqcpxx8ygWkV+8Md5gdP8XUkDfhv92yU3K2EKaW1ji77daw9JAExPlZak4rX8LE sMgLDc4QpcDuLmkD6awMTGqP+aKYbwAhwvyZuFlYUqKdycxWOz8BqfghYIUnjxQn33xE w1ig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=baxX1S5LtzfmqzAc72hpJ9BN2ZK/N6upcf+SaQYT9NE=; b=pB1SqkhQxZ3juZ0fcQvqiXU7qDALsXzm3s6Wuw/+hmlUKW8ZOJnJpCZ7JlhOcT2TOf HCRVvvxYOFBTEIUAWkN4NQFMZn3/p8M9L60OML3hZiCd8FOZWjA/Cdt06c5gEWGgL44i GZOjJLYj0bluvIAAGotZDVGeNITItl2m0TsVfvTMB7QmzL7+v5ywuaMFM3NyUiuAIebv Xth3T4er/ktxXKhDWzjgK/LSNx/XWQdw91xuUjU/Y0WV/q7FsqbkF7CLM+MdyiArrIxw sr1ajS8EhBZoFmARkzipaJMIYGHP0xYfZYrRsTdB5wOQJesItYdgKM5zip/6kyfU8LNW GqxA== X-Gm-Message-State: AHQUAuYVfwEH1zQktjX5H29s46vn0+Wnqu6xGd5p9/oeB+hLMFoMsaWY 42w8mHM/9vIKPe1iVzV8nzuB804nQegSyCY45tMjIOF4WyekjHnZtt6shZjJG7Vz0iSZpSyFoFX 0BoBJgc1Q8jWkc1HU+hA3dBOVMKuonSxggDeASR9tFFv+0Tos6ucSQusBtzRPlIwNjlQ= X-Google-Smtp-Source: AHgI3Ib/imDfoZJ4ItLCNcbF5XtYkjqiznblt6qKt1+LhMd5yLSVUg6ce1CYUmoalvSop74kbXFYdi7LJg== X-Received: by 2002:aa7:8718:: with SMTP id b24mr9117456pfo.139.1551239693479; Tue, 26 Feb 2019 19:54:53 -0800 (PST) Date: Tue, 26 Feb 2019 19:54:45 -0800 Message-Id: <20190227035448.117169-1-fengc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.21.0.rc2.261.ga7da99ff1b-goog Subject: [RFC dma-buf 0/3] Improve the dma-buf tracking From: Chenbo Feng To: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Cc: Sumit Semwal , erickreyes@google.com, Chenbo Feng Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, all dma-bufs share the same anonymous inode. While we can count how many dma-buf fds or mappings a process has, we can't get the size of the backing buffers or tell if two entries point to the same dma-buf. And in debugfs, we can get a per-buffer breakdown of size and reference count, but can't tell which processes are actually holding the references to each buffer. To resolve the issue above and provide better method for userspace to track the dma-buf usage across different processes, the following changes are proposed in dma-buf kernel side. First of all, replace the singleton inode inside the dma-buf subsystem with a mini-filesystem, and assign each dma-buf a unique inode out of this filesystem. With this change, calling stat(2) on each entry gives the caller a unique ID (st_ino), the buffer's size (st_size), and even the number of pages assigned to each dma-buffer. Secoundly, add the inode information to /sys/kernel/debug/dma_buf/bufinfo so in the case where a buffer is mmap()ed into a process=E2=80=99s address = space but all remaining fds have been closed, we can still get the dma-buf information and try to accociate it with the process by searching the proc/pid/maps and looking for the corresponding inode number exposed in dma-buf debug fs. Thirdly, created an ioctl to assign names to dma-bufs which lets userspace assign short names (e.g., "CAMERA") to buffers. This information can be extremely helpful for tracking and accounting shared buffers based on their usage and original purpose. Last but not least, add dma-buf information to /proc/pid/fdinfo by adding a show_fdinfo() handler to dma_buf_file_operations. The handler will print the file_count and name of each buffer. Greg Hackmann (3): dma-buf: give each buffer a full-fledged inode dma-buf: add DMA_BUF_{GET,SET}_NAME ioctls dma-buf: add show_fdinfo handler drivers/dma-buf/dma-buf.c | 121 ++++++++++++++++++++++++++++++++--- include/linux/dma-buf.h | 5 +- include/uapi/linux/dma-buf.h | 4 ++ include/uapi/linux/magic.h | 1 + 4 files changed, 122 insertions(+), 9 deletions(-) --=20 2.21.0.rc2.261.ga7da99ff1b-goog