Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859Ab2JFIUf (ORCPT ); Sat, 6 Oct 2012 04:20:35 -0400 Received: from 1wt.eu ([62.212.114.60]:35984 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753453Ab2JFIU2 (ORCPT ); Sat, 6 Oct 2012 04:20:28 -0400 Date: Sat, 6 Oct 2012 10:20:16 +0200 From: Willy Tarreau To: Chris Wilson Cc: Daniel Vetter , linux-kernel@vger.kernel.org, Dave Airlie Subject: Re: 3.5 regression on i915 Message-ID: <20121006082016.GA22618@1wt.eu> References: <20121005234218.GC21163@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5197 Lines: 113 Hi Chris, On Sat, Oct 06, 2012 at 09:04:34AM +0100, Chris Wilson wrote: > > The crash happens here in i915_gem_entervt_ioctl() : > > > > 3659 BUG_ON(!list_empty(&dev_priv->mm.active_list)); > > 3660 BUG_ON(!list_empty(&dev_priv->mm.flushing_list)); > > -> 3661 BUG_ON(!list_empty(&dev_priv->mm.inactive_list)); > > 3662 mutex_unlock(&dev->struct_mutex); > > That BUG_ON there is silly and can simply be removed. The check is to > verify that no batches were submitted to the kernel whilst the UMS/GEM > client was suspended - to which the BUG_ONs are a crude approximation. > Furthermore, the checks are too late, since it means we attempted to > program the hardware whilst it was in an invalid state, the BUG_ONs are > the least of your concerns at that point. Excellent, that fixed it ! X still segfaults when KMS is used, but I expect more of a pure user-space issue here since there is nothing in dmesg. Would some of you accept the following patch and tag it for -stable ? Thanks, Willy --- >From 3450cb7b7bd0b8fe1eab59d09e6852c4e3b22001 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Sat, 6 Oct 2012 10:09:00 +0200 Subject: drm/i915: remove useless BUG_ON which caused a regression in 3.5. starting an old X server causes a kernel BUG since commit 1b50247a8d: ------------[ cut here ]------------ kernel BUG at drivers/gpu/drm/i915/i915_gem.c:3661! invalid opcode: 0000 [#1] SMP Modules linked in: snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss uvcvideo videobuf2_core videodev videobuf2_vmalloc videobuf2_memops uhci_hcd ath9k mac80211 snd_hda_codec_realtek ath9k_common microcode ath9k_hw psmouse serio_raw sg ath cfg80211 atl1c lpc_ich mfd_core ehci_hcd snd_hda_intel snd_hda_codec snd_hwdep snd_pcm rtc_cmos snd_timer snd evdev eeepc_laptop snd_page_alloc sparse_keymap Pid: 2866, comm: X Not tainted 3.5.6-rc1-eeepc #1 ASUSTeK Computer INC. 1005HA/1005HA EIP: 0060:[] EFLAGS: 00013297 CPU: 0 EIP is at i915_gem_entervt_ioctl+0xf1/0x110 EAX: f5941df4 EBX: f5940000 ECX: 00000000 EDX: 00020000 ESI: f5835400 EDI: 00000000 EBP: f51d7e38 ESP: f51d7e20 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 CR0: 8005003b CR2: b760e0a0 CR3: 351b6000 CR4: 000007d0 DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 DR6: ffff0ff0 DR7: 00000400 Process X (pid: 2866, ti=f51d6000 task=f61af8d0 task.ti=f51d6000) Stack: 00000001 00000000 f5835414 f51d7e84 f5835400 f54f85c0 f51d7f10 c12b530b 00000001 c151b139 c14751b6 c152e030 00000b32 00006459 00000059 0000e200 00000001 00000000 00006459 c159ddd0 c12dc1a0 ffffffea 00000000 00000000 Call Trace: [] drm_ioctl+0x2eb/0x440 [] ? i915_gem_init+0xe0/0xe0 [] ? enqueue_hrtimer+0x1b/0x50 [] ? __hrtimer_start_range_ns+0x161/0x330 [] ? lock_hrtimer_base+0x23/0x50 [] ? hrtimer_try_to_cancel+0x33/0x70 [] ? drm_version+0x90/0x90 [] vfs_ioctl+0x31/0x50 [] do_vfs_ioctl+0x64/0x510 [] ? hrtimer_nanosleep+0x8e/0x100 [] ? update_rmtp+0x80/0x80 [] sys_ioctl+0x39/0x60 [] syscall_call+0x7/0xb Code: 83 c4 0c 5b 5e 5f 5d c3 c7 44 24 04 2c 05 53 c1 c7 04 24 6f ef 47 c1 e8 6e e0 fd ff c7 83 38 1e 00 00 00 00 00 00 e9 3f ff ff ff <0f> 0b eb fe 0f 0b eb fe 8d b4 26 00 00 00 00 0f 0b eb fe 8d b6 EIP: [] i915_gem_entervt_ioctl+0xf1/0x110 SS:ESP 0068:f51d7e20 ---[ end trace dd332ec083cbd513 ]--- The crash happens here in i915_gem_entervt_ioctl() : 3659 BUG_ON(!list_empty(&dev_priv->mm.active_list)); 3660 BUG_ON(!list_empty(&dev_priv->mm.flushing_list)); -> 3661 BUG_ON(!list_empty(&dev_priv->mm.inactive_list)); 3662 mutex_unlock(&dev->struct_mutex); Quoting Chris : "That BUG_ON there is silly and can simply be removed. The check is to verify that no batches were submitted to the kernel whilst the UMS/GEM client was suspended - to which the BUG_ONs are a crude approximation. Furthermore, the checks are too late, since it means we attempted to program the hardware whilst it was in an invalid state, the BUG_ONs are the least of your concerns at that point." Cc: Chris Wilson Signed-off-by: Willy Tarreau --- drivers/gpu/drm/i915/i915_gem.c | 1 - 1 files changed, 0 insertions(+), 1 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 35926ad..fc6683a 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3658,7 +3658,6 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data, BUG_ON(!list_empty(&dev_priv->mm.active_list)); BUG_ON(!list_empty(&dev_priv->mm.flushing_list)); - BUG_ON(!list_empty(&dev_priv->mm.inactive_list)); mutex_unlock(&dev->struct_mutex); ret = drm_irq_install(dev); -- 1.7.2.1.45.g54fbc -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/