From patchwork Tue Feb 12 13:08:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10807891 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7A474746 for ; Tue, 12 Feb 2019 13:08:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6A3E82B686 for ; Tue, 12 Feb 2019 13:08:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5E51B2B6FD; Tue, 12 Feb 2019 13:08:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0F9632B686 for ; Tue, 12 Feb 2019 13:08:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 80E5F6E07C; Tue, 12 Feb 2019 13:08:47 +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 6B3746E062 for ; Tue, 12 Feb 2019 13:08:43 +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 15550284-1500050 for multiple; Tue, 12 Feb 2019 13:08:33 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 12 Feb 2019 13:08:30 +0000 Message-Id: <20190212130831.14425-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 1/2] drm/i915: Recursive i915_reset_trylock() verboten X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mika Kuoppala Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP We cannot nest i915_reset_trylock() as the inner may wait for the I915_RESET_BACKOFF which in turn is waiting upon sync_srcu who is waiting for our outermost lock. As we take the reset srcu around the fence update, we have to defer taking it in i915_gem_fault() until after we acquire the pin on the fence to avoid nesting. This is a little ugly, but still works. If a reset occurs between i915_vma_pin_fence() and the second reset lock, the reset will restore the fence register back to the pinned value before the reset lock allows us to proceed (our mmap won't be revoked as we haven't yet marked it as being a userfault as that requires us to hold the reset lock), so the pagefault is still serialised with the revocation in reset. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109605 Fixes: 2caffbf11762 ("drm/i915: Revoke mmaps and prevent access to fence registers across reset") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala --- drivers/gpu/drm/i915/i915_gem.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index c8c355bec091..ae1467a74a08 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1923,16 +1923,16 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) if (ret) goto err_unpin; + ret = i915_vma_pin_fence(vma); + if (ret) + goto err_unpin; + srcu = i915_reset_trylock(dev_priv); if (srcu < 0) { ret = srcu; - goto err_unpin; + goto err_fence; } - ret = i915_vma_pin_fence(vma); - if (ret) - goto err_reset; - /* Finally, remap it using the new GTT offset */ ret = remap_io_mapping(area, area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT), @@ -1940,7 +1940,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) min_t(u64, vma->size, area->vm_end - area->vm_start), &ggtt->iomap); if (ret) - goto err_fence; + goto err_reset; /* Mark as being mmapped into userspace for later revocation */ assert_rpm_wakelock_held(dev_priv); @@ -1950,10 +1950,10 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) i915_vma_set_ggtt_write(vma); -err_fence: - i915_vma_unpin_fence(vma); err_reset: i915_reset_unlock(dev_priv, srcu); +err_fence: + i915_vma_unpin_fence(vma); err_unpin: __i915_vma_unpin(vma); err_unlock: From patchwork Tue Feb 12 13:08:31 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10807889 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B13CE746 for ; Tue, 12 Feb 2019 13:08:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A264F2B686 for ; Tue, 12 Feb 2019 13:08:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 93CB02B6FD; Tue, 12 Feb 2019 13:08:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4D2E82B686 for ; Tue, 12 Feb 2019 13:08:45 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9995F6E062; Tue, 12 Feb 2019 13:08:44 +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 705796E07C for ; Tue, 12 Feb 2019 13:08:43 +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 15550286-1500050 for multiple; Tue, 12 Feb 2019 13:08:33 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 12 Feb 2019 13:08:31 +0000 Message-Id: <20190212130831.14425-2-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190212130831.14425-1-chris@chris-wilson.co.uk> References: <20190212130831.14425-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 2/2] drm/i915: Detect potential i915_reset_trylock() lockups X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mika Kuoppala Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Use lockdep to warn before we wait indefinitely in case we may be waiting indefinitely. Suggested-by: Mika Kuoppala References: 2caffbf11762 ("drm/i915: Revoke mmaps and prevent access to fence registers across reset") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala --- drivers/gpu/drm/i915/i915_reset.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c index c1b53533ada6..12e74decd7a2 100644 --- a/drivers/gpu/drm/i915/i915_reset.c +++ b/drivers/gpu/drm/i915/i915_reset.c @@ -1305,6 +1305,9 @@ int i915_reset_trylock(struct drm_i915_private *i915) struct i915_gpu_error *error = &i915->gpu_error; int srcu; + might_lock(&error->reset_backoff_srcu); + might_sleep(); + rcu_read_lock(); while (test_bit(I915_RESET_BACKOFF, &error->flags)) { rcu_read_unlock();