From patchwork Wed Jan 1 14:10:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11315093 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 346AD6C1 for ; Wed, 1 Jan 2020 14:10:15 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 118DD2072C for ; Wed, 1 Jan 2020 14:10:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 118DD2072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 180EC8933D; Wed, 1 Jan 2020 14:10:13 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7F9288933D for ; Wed, 1 Jan 2020 14:10:10 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 19742073-1500050 for ; Wed, 01 Jan 2020 14:10:07 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Wed, 1 Jan 2020 14:10:07 +0000 Message-Id: <20200101141007.755429-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.25.0.rc0 MIME-Version: 1.0 Subject: [Intel-gfx] [CI] drm/i915/gem: Drop local vma->vm_file reference X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" We use the global device inode, shared amongst all files, and not the user's device filp to provide the backing storage for the mmap. The vma->vm_file provides a redundant reference that breaks existing expected behaviour that closing the user's device fd will release the resources bound to it, if a mmap persists. (Even without the vma->vm_file, the mmap will persist past the user's fd as the storage is bound to the device, i.e. our reference is on the object not file.) Fixes: cc662126b413 ("drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET") Closes: https://gitlab.freedesktop.org/drm/intel/issues/919 Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 59 ++++++++++++++++++++++++ drivers/gpu/drm/i915/i915_drv.h | 10 ++++ 2 files changed, 69 insertions(+) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 905527ce2999..ed0d9a2f0e7b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -4,6 +4,7 @@ * Copyright © 2014-2016 Intel Corporation */ +#include #include #include #include @@ -686,6 +687,46 @@ static const struct vm_operations_struct vm_ops_cpu = { .close = vm_close, }; +static int singleton_release(struct inode *inode, struct file *file) +{ + struct drm_i915_private *i915 = file->private_data; + + cmpxchg(&i915->gem.mmap_singleton, file, NULL); + drm_dev_put(&i915->drm); + + return 0; +} + +static const struct file_operations singleton_fops = { + .owner = THIS_MODULE, + .release = singleton_release, +}; + +static struct file *mmap_singleton(struct drm_i915_private *i915) +{ + struct file *file; + + rcu_read_lock(); + file = i915->gem.mmap_singleton; + if (file && !get_file_rcu(file)) + file = NULL; + rcu_read_unlock(); + if (file) + return file; + + file = anon_inode_getfile("i915.gem", &singleton_fops, i915, O_RDWR); + if (IS_ERR(file)) + return file; + + /* Everyone shares a single global address space */ + file->f_mapping = i915->drm.anon_inode->i_mapping; + + smp_store_mb(i915->gem.mmap_singleton, file); + drm_dev_get(&i915->drm); + + return file; +} + /* * This overcomes the limitation in drm_gem_mmap's assignment of a * drm_gem_object as the vma->vm_private_data. Since we need to @@ -699,6 +740,7 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma) struct drm_device *dev = priv->minor->dev; struct i915_mmap_offset *mmo = NULL; struct drm_gem_object *obj = NULL; + struct file *anon; if (drm_dev_is_unplugged(dev)) return -ENODEV; @@ -747,9 +789,26 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma) vma->vm_flags &= ~VM_MAYWRITE; } + anon = mmap_singleton(to_i915(obj->dev)); + if (IS_ERR(anon)) { + drm_gem_object_put_unlocked(obj); + return PTR_ERR(anon); + } + vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_private_data = mmo; + /* + * We keep the ref on mmo->obj, not vm_file, but we require + * vma->vm_file->f_mapping, see vma_link(), for later revocation. + * Our userspace is accustomed to having per-file resource cleanup + * (i.e. contexts, objects and requests) on their close(fd), which + * requires avoiding extraneous references to their filp, hence why + * we prefer to use an anonymous file for their mmaps. + */ + fput(vma->vm_file); + vma->vm_file = anon; + switch (mmo->mmap_type) { case I915_MMAP_TYPE_WC: vma->vm_page_prot = diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 2c7e3020e766..2ee9f57d165d 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1252,6 +1252,16 @@ struct drm_i915_private { struct llist_head free_list; struct work_struct free_work; } contexts; + + /* + * We replace the local file with a global mappings as the + * backing storage for the mmap is on the device and not + * on the struct file, and we do not want to prolong the + * lifetime of the local fd. To minimise the number of + * anonymous inodes we create, we use a global singleton to + * share the global mapping. + */ + struct file *mmap_singleton; } gem; u8 pch_ssc_use;