From patchwork Mon Jan 23 19:17:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "T.J. Mercier" X-Patchwork-Id: 13112835 X-Patchwork-Delegate: paul@paul-moore.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9DBDBC38142 for ; Mon, 23 Jan 2023 19:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232417AbjAWTSO (ORCPT ); Mon, 23 Jan 2023 14:18:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232402AbjAWTSF (ORCPT ); Mon, 23 Jan 2023 14:18:05 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99579126E1 for ; Mon, 23 Jan 2023 11:18:03 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id i10-20020a25f20a000000b006ea4f43c0ddso14237185ybe.21 for ; Mon, 23 Jan 2023 11:18:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=9WOZzSEfhu/PT9TWBWMQDCCNsrofWV34oFDU/0sj1mQ=; b=CLJ2JxK/Tm4oa2T67r1/7AoCewa4cPoaCpXx/gVHbZ1m+FYlbdBISpcie92wke9qiT ywnZGTRRWgUyvtV2GeIN6CSF1A1BpACoPsOvCJSqkdka36IG7lwA9jHJB0/1Y37BiDn6 UZyz4QR44eh7OHGKOjLnRuXG7qELlMRlfRNYaxnDlTMYAnQZZAKF7GLGFraikV5q7pPa PqEGE55YfXGgQoOaL42PCJmSLM5OLIrr2pXTamoSK+ZBJQZ3xablgI1e6ZxykShX+C1V OGCeujU9/+VSQurUIb0N4LKyFw0PX0Xvt3l2bOlWDy6qNiZqzVXsJcA5m/zeCrF4rUUR ohNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9WOZzSEfhu/PT9TWBWMQDCCNsrofWV34oFDU/0sj1mQ=; b=xI0oeYCBtvGEpK2caRxOkWZrqfatMJYlnwX1tfnEar7z6uMCBR8uTFts0ciHKilIl1 mkoaZPiH+cTBbviBgG0wdxOjwnsozGtJTbovu7vt6HQsMygulHUnkHTZaWoB958AvPbj UIICvqHoqibpvKs2YUVHWVpW9Pg1g3nYXjHiSMtJhQCO5cnDg+yM5v770a2HyCg+9IQh 5CQRtrzyexcuMBHOPtOAjvdkr6jM15YLX9ZO0jONL4Nu5aps+zB7WVL1cAXQSI6QZZZ+ 9TA72HAYDFgKNRfAl6EDmfxZwS+E1j1HtL4U/68OWw1wj4NIrNr/o148xfGZ++He+g00 SSUg== X-Gm-Message-State: AFqh2kohIGYZan3PBHdWzizJ5t81dS9MhgWlCO2RQMCzWZSBSulgt1OQ VrOcjKvFtTdyHYxMAqIPG1Yw7FaFIEAG+TY= X-Google-Smtp-Source: AMrXdXt5UsJV8XnGROzCqwUjMEtxGJTY0AAa2SUnm4rAwiP8wDQKiwcGvs1ceYITQIG6UCVtpU2h3/VNxLbuwi8= X-Received: from tj.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:53a]) (user=tjmercier job=sendgmr) by 2002:a25:dc92:0:b0:7b0:3379:9c00 with SMTP id y140-20020a25dc92000000b007b033799c00mr3149691ybe.359.1674501483256; Mon, 23 Jan 2023 11:18:03 -0800 (PST) Date: Mon, 23 Jan 2023 19:17:24 +0000 In-Reply-To: <20230123191728.2928839-1-tjmercier@google.com> Mime-Version: 1.0 References: <20230123191728.2928839-1-tjmercier@google.com> X-Mailer: git-send-email 2.39.0.246.g2a6d74b583-goog Message-ID: <20230123191728.2928839-3-tjmercier@google.com> Subject: [PATCH v2 2/4] dmabuf: Add cgroup charge transfer function From: "T.J. Mercier" To: tjmercier@google.com, Sumit Semwal , " =?utf-8?q?Christian_K=C3=B6nig?= " Cc: hannes@cmpxchg.org, daniel.vetter@ffwll.ch, android-mm@google.com, jstultz@google.com, jeffv@google.com, cmllamas@google.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, cgroups@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org The dma_buf_transfer_charge function provides a way for processes to transfer charge of a buffer to a different cgroup. This is essential for the cases where a central allocator process does allocations for various subsystems, hands over the fd to the client who requested the memory, and drops all references to the allocated memory. Signed-off-by: T.J. Mercier --- drivers/dma-buf/dma-buf.c | 56 ++++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 1 + include/linux/memcontrol.h | 5 ++++ 3 files changed, 62 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index a6a8cb5cb32d..ac3d02a7ecf8 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -11,6 +11,7 @@ * refining of this idea. */ +#include #include #include #include @@ -1626,6 +1627,61 @@ void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map) } EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, DMA_BUF); +/** + * dma_buf_transfer_charge - Change the cgroup to which the provided dma_buf is charged. + * @dmabuf_file: [in] file for buffer whose charge will be migrated to a different cgroup + * @target: [in] the task_struct of the destination process for the cgroup charge + * + * Only tasks that belong to the same cgroup the buffer is currently charged to + * may call this function, otherwise it will return -EPERM. + * + * Returns 0 on success, or a negative errno code otherwise. + */ +int dma_buf_transfer_charge(struct file *dmabuf_file, struct task_struct *target) +{ + struct mem_cgroup *current_cg, *target_cg; + struct dma_buf *dmabuf; + unsigned int nr_pages; + int ret = 0; + + if (!IS_ENABLED(CONFIG_MEMCG)) + return 0; + + if (WARN_ON(!dmabuf_file) || WARN_ON(!target)) + return -EINVAL; + + if (!is_dma_buf_file(dmabuf_file)) + return -EBADF; + dmabuf = dmabuf_file->private_data; + + nr_pages = PAGE_ALIGN(dmabuf->size) / PAGE_SIZE; + current_cg = mem_cgroup_from_task(current); + target_cg = get_mem_cgroup_from_mm(target->mm); + + if (current_cg == target_cg) + goto skip_transfer; + + if (!mem_cgroup_charge_dmabuf(target_cg, nr_pages, GFP_KERNEL)) { + ret = -ENOMEM; + goto skip_transfer; + } + + if (cmpxchg(&dmabuf->memcg, current_cg, target_cg) != current_cg) { + /* Only the current owner can transfer the charge */ + ret = -EPERM; + mem_cgroup_uncharge_dmabuf(target_cg, nr_pages); + goto skip_transfer; + } + + mem_cgroup_uncharge_dmabuf(current_cg, nr_pages); + mem_cgroup_put(current_cg); /* unref from buffer - buffer keeps new ref to target_cg */ + return 0; + +skip_transfer: + mem_cgroup_put(target_cg); + return ret; +} + #ifdef CONFIG_DEBUG_FS static int dma_buf_debug_show(struct seq_file *s, void *unused) { diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 1f0ffb8e4bf5..f25eb8e60fb2 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -634,4 +634,5 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map); void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map); int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map); void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map); +int dma_buf_transfer_charge(struct file *dmabuf_file, struct task_struct *target); #endif /* __DMA_BUF_H__ */ diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index c10b8565fdbf..009298a446fe 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1335,6 +1335,11 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css) return NULL; } +static inline struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) +{ + return NULL; +} + static inline void obj_cgroup_put(struct obj_cgroup *objcg) { }