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Fri, 22 Jan 2021 08:35:48 -0500 X-MC-Unique: OP9_3mXzPNOM-cxgZQGzZA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 03C76107ACE3; Fri, 22 Jan 2021 13:35:47 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-112-182.ams2.redhat.com [10.36.112.182]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B5DC810023BD; Fri, 22 Jan 2021 13:35:46 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 0BE5F18000AB; Fri, 22 Jan 2021 14:35:45 +0100 (CET) Date: Fri, 22 Jan 2021 14:35:45 +0100 From: Gerd Hoffmann To: Thomas Zimmermann Subject: Re: [PATCH v3 2/4] drm/qxl: unpin release objects Message-ID: <20210122133545.acloe4ytgp6r4iql@sirius.home.kraxel.org> References: <20210120111240.2509679-1-kraxel@redhat.com> <20210120111240.2509679-3-kraxel@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Cc: David Airlie , open list , dri-devel@lists.freedesktop.org, "open list:DRM DRIVER FOR QXL VIRTUAL GPU" , Dave Airlie , "open list:DRM DRIVER FOR QXL VIRTUAL GPU" X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Fri, Jan 22, 2021 at 09:13:42AM +0100, Thomas Zimmermann wrote: > Hi > > Am 20.01.21 um 12:12 schrieb Gerd Hoffmann: > > Balances the qxl_create_bo(..., pinned=true, ...); > > call in qxl_release_bo_alloc(). > > > > Signed-off-by: Gerd Hoffmann > > --- > > drivers/gpu/drm/qxl/qxl_release.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c > > index 0fcfc952d5e9..add979cba11b 100644 > > --- a/drivers/gpu/drm/qxl/qxl_release.c > > +++ b/drivers/gpu/drm/qxl/qxl_release.c > > @@ -166,6 +166,7 @@ qxl_release_free_list(struct qxl_release *release) > > entry = container_of(release->bos.next, > > struct qxl_bo_list, tv.head); > > bo = to_qxl_bo(entry->tv.bo); > > + bo->tbo.pin_count = 0; /* ttm_bo_unpin(&bo->tbo); */ > > This code looks like a workaround or a bug. > > AFAICT the only place with pre-pinned BO is qdev->dumb_shadow_bo. Can you > remove the pinned flag entirely and handle pinning as part of > dumb_shadow_bo's code. No, the release objects are pinned too, and they must be pinned (qxl commands are in there, and references are placed in the qxl rings, so allowing them to roam is a non-starter). > if (pin_count) > ttm_bo_unpin(); > WARN_ON(pin_count); /* should always be 0 now */ Well, the pin_count is 1 at this point. No need for the if(). Just calling ttm_bo_unpin() here makes lockdep unhappy. Not calling ttm_bo_unpin() makes ttm_bo_release() throw a WARN() because of the pin. Clearing pin_count (which is how ttm fixes things up in the error path) works. I'm open to better ideas. take care, Gerd _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization