From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06085C07E85 for ; Mon, 3 Dec 2018 20:15:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2087E2087F for ; Mon, 3 Dec 2018 20:14:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2087E2087F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=anholt.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726098AbeLCUO5 (ORCPT ); Mon, 3 Dec 2018 15:14:57 -0500 Received: from anholt.net ([50.246.234.109]:53288 "EHLO anholt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726003AbeLCUO5 (ORCPT ); Mon, 3 Dec 2018 15:14:57 -0500 Received: from localhost (localhost [127.0.0.1]) by anholt.net (Postfix) with ESMTP id 6254C10A12C6; Mon, 3 Dec 2018 12:14:55 -0800 (PST) X-Virus-Scanned: Debian amavisd-new at anholt.net Received: from anholt.net ([127.0.0.1]) by localhost (kingsolver.anholt.net [127.0.0.1]) (amavisd-new, port 10024) with LMTP id uHojUlnKaulw; Mon, 3 Dec 2018 12:14:54 -0800 (PST) Received: from eliezer.anholt.net (localhost [127.0.0.1]) by anholt.net (Postfix) with ESMTP id 03AFD10A0388; Mon, 3 Dec 2018 12:14:54 -0800 (PST) Received: by eliezer.anholt.net (Postfix, from userid 1000) id 842112FE2D16; Mon, 3 Dec 2018 12:14:53 -0800 (PST) From: Eric Anholt To: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, christian.koenig@amd.com Cc: linux-kernel@vger.kernel.org, Eric Anholt Subject: [PATCH] drm/sched: Fix a use-after-free when tracing the scheduler. Date: Mon, 3 Dec 2018 12:14:53 -0800 Message-Id: <20181203201453.25773-1-eric@anholt.net> X-Mailer: git-send-email 2.20.0.rc1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With DEBUG_SLAB (poisoning on free) enabled, I could quickly produce an oops when tracing V3D. Signed-off-by: Eric Anholt --- I think this patch is correct (though maybe a bigger refactor could avoid the extra get/put?), but I've still got this with "vblank_mode=0 perf record -a -e v3d:.\* -e gpu_scheduler:.\* glxgears". Any ideas? [ 139.842191] Unable to handle kernel NULL pointer dereference at virtual address 00000020 [ 139.850413] pgd = eab7bb57 [ 139.854424] [00000020] *pgd=80000040004003, *pmd=00000000 [ 139.860523] Internal error: Oops: 206 [#1] SMP ARM [ 139.865340] Modules linked in: [ 139.868404] CPU: 0 PID: 1161 Comm: v3d_render Not tainted 4.20.0-rc4+ #552 [ 139.875287] Hardware name: Broadcom STB (Flattened Device Tree) [ 139.881228] PC is at perf_trace_drm_sched_job_wait_dep+0xa8/0xf4 [ 139.887243] LR is at 0xe9790274 [ 139.890388] pc : [] lr : [] psr: a0050013 [ 139.896662] sp : ed21dec0 ip : ed21dec0 fp : ed21df04 [ 139.901893] r10: ed267478 r9 : 00000000 r8 : ff7bde04 [ 139.907123] r7 : 00000000 r6 : 00000063 r5 : 00000000 r4 : c1208448 [ 139.913659] r3 : c1265690 r2 : ff7bf660 r1 : 00000034 r0 : ff7bf660 [ 139.920196] Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user [ 139.927339] Control: 30c5383d Table: 68fa3b40 DAC: fffffffd [ 139.933095] Process v3d_render (pid: 1161, stack limit = 0xb3c84b1b) [ 139.939457] Stack: (0xed21dec0 to 0xed21e000) [ 139.943821] dec0: 20050013 ffffffff eb9700cc 00000000 ec0e8e80 00000000 eb9700cc e9790274 [ 139.952009] dee0: 00000000 e2f59345 eb970078 eba8f680 c12ae00c c1208478 00000000 e8c2b048 [ 139.960197] df00: eb9700cc c06e92e4 c06e8f04 00000000 80050013 ed267478 eb970078 00000000 [ 139.968385] df20: ed267578 c0e45ae0 e9093080 c06e831c ed267630 c06e8120 c06e77d4 c1208448 [ 139.976573] df40: ee2e8acc 00000001 00000000 ee2e8640 c0272ab4 ed21df54 ed21df54 e2f59345 [ 139.984762] df60: ed21c000 ed1b4800 ed2d7840 00000000 ed21c000 ed267478 c06e8084 ee935cb0 [ 139.992950] df80: ed1b4838 c0249b44 ed21c000 ed2d7840 c02499e4 00000000 00000000 00000000 [ 140.001138] dfa0: 00000000 00000000 00000000 c02010ac 00000000 00000000 00000000 00000000 [ 140.009326] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [ 140.017514] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 [ 140.025707] [] (perf_trace_drm_sched_job_wait_dep) from [] (drm_sched_entity_pop_job+0x394/0x438) [ 140.036332] [] (drm_sched_entity_pop_job) from [] (drm_sched_main+0x9c/0x298) [ 140.045221] [] (drm_sched_main) from [] (kthread+0x160/0x168) [ 140.052716] [] (kthread) from [] (ret_from_fork+0x14/0x28) drivers/gpu/drm/scheduler/sched_entity.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 4463d3826ecb..0d4fc86089cb 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -440,13 +440,15 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) while ((entity->dependency = sched->ops->dependency(sched_job, entity))) { - + dma_fence_get(entity->dependency); if (drm_sched_entity_add_dependency_cb(entity)) { trace_drm_sched_job_wait_dep(sched_job, entity->dependency); + dma_fence_put(entity->dependency); return NULL; } + dma_fence_put(entity->dependency); } /* skip jobs from entity that marked guilty */ -- 2.20.0.rc1