From patchwork Sat Jul 9 08:38:50 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 958932 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p698dZjY004629 for ; Sat, 9 Jul 2011 08:39:56 GMT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 314059ED6B for ; Sat, 9 Jul 2011 01:39:34 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (server109-228-6-236.live-servers.net [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id 26415A02F1 for ; Sat, 9 Jul 2011 01:38:54 -0700 (PDT) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.66.37; Received: from arrandale.alporthouse.com (unverified [78.156.66.37]) by fireflyinternet.com (Firefly Internet SMTP) with ESMTP id 39130550-1500050 for multiple; Sat, 09 Jul 2011 09:38:52 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Sat, 9 Jul 2011 09:38:50 +0100 Message-Id: <1310200731-18086-1-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 1.7.5.4 X-Originating-IP: 78.156.66.37 Subject: [Intel-gfx] [PATCH 1/2] drm/i915: Prefault all pages for pread and pwrite X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Sat, 09 Jul 2011 08:39:56 +0000 (UTC) When using a GTT mapping as a source or destination for the pwrite or pread command respectively, unless the PTEs for the GTT vma had been prepopulated then get_user_pages() would fail with EFAULT. Usually, we only write small amounts of data with pwrite that happened to be conveniently prefaulted by the 2-page fault_in_pages_readable. By prefaulting all pages before we take the struct mutex, we avoid this issue, can stay in the fast path longer and reduce the likelihood of a recursive deadlock. "Fixes" gem_mmap_gtt. References: https://bugs.freedesktop.org/show_bug.cgi?id=38115 Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/i915_gem.c | 34 ++++++++++++++++++++++++++++++---- 1 files changed, 30 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 4fc9738..2fce620 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -503,6 +503,19 @@ out: return ret; } +static int prefault_writeable(unsigned long uaddr, unsigned long len) +{ + int ret = 0; + + len += uaddr; + while (uaddr < len) { + ret |= __put_user(0, (char __user *)uaddr); + uaddr += 4096; + } + + return ret ? -EFAULT : 0; +} + /** * Reads data from the object referenced by handle. * @@ -524,8 +537,7 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data, args->size)) return -EFAULT; - ret = fault_in_pages_writeable((char __user *)(uintptr_t)args->data_ptr, - args->size); + ret = prefault_writeable(args->data_ptr, args->size); if (ret) return -EFAULT; @@ -943,6 +955,21 @@ out: return ret; } +static int prefault_readable(unsigned long uaddr, unsigned long len) +{ + volatile char c; + int ret = 0; + + len += uaddr; + while (uaddr < len) { + ret |= __get_user(c, (const char __user *)uaddr); + uaddr += 4096; + } + + return ret ? -EFAULT : 0; + (void)c; +} + /** * Writes data to the object referenced by handle. * @@ -964,8 +991,7 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data, args->size)) return -EFAULT; - ret = fault_in_pages_readable((char __user *)(uintptr_t)args->data_ptr, - args->size); + ret = prefault_readable(args->data_ptr, args->size); if (ret) return -EFAULT;