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From:   Ondrej Zary <linux@zary.sk>
To:     Ben Skeggs <bskeggs@redhat.com>
Subject: Re: nouveau broken on Riva TNT2 in 5.13.0-rc4: NULL pointer dereference in nouveau_bo_sync_for_device
Date:   Tue, 8 Jun 2021 22:01:56 +0200
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Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Christian =?iso-8859-1?q?K=F6nig?= <christian.koenig@amd.com>
References: <202106052143.52488.linux@zary.sk> <202106072258.43836.linux@zary.sk> <202106082047.42658.linux@zary.sk>
In-Reply-To: <202106082047.42658.linux@zary.sk>
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On Tuesday 08 June 2021 20:47:42 Ondrej Zary wrote:
> On Monday 07 June 2021 22:58:43 Ondrej Zary wrote:
> > On Sunday 06 June 2021 23:16:03 Ondrej Zary wrote:
> > > On Saturday 05 June 2021 23:34:23 Ondrej Zary wrote:
> > > > On Saturday 05 June 2021 21:43:52 Ondrej Zary wrote:
> > > > > Hello,
> > > > > I'm testing 5.13.0-rc4 and nouveau crashes with NULL pointer dereference in nouveau_bo_sync_for_device.
> > > > > Found various reports like this but that was back in februaryso that should be fixed now.
> > > > 
> > > > So it is the same bug. Broken since 5.11. This revert fixes it in 5.11:
> > > > https://lists.freedesktop.org/archives/dri-devel/2021-February/298531.html
> > > > 
> > > > Added some debug printks to nouveau_bo_sync_for_device:
> > > > [   22.225048] ttm_dma=fc33b500
> > > > [   22.225066] ttm_dma->num_pages=18
> > > > [   22.225071] i=0 num_pages=16
> > > > [   22.225077] ttm_dma->dma_address=00000000
> > > > [   22.225094] BUG: kernel NULL pointer dereference, address: 00000000
> > > > 
> > > > So ttm->dma_address is NULL.
> > > > 
> > > 
> > > Tested reverting f295c8cfec833c2707ff1512da10d65386dde7af again and it does not work...
> > > Not sure what I did before.
> > > 
> > > Bisecting between 5.10 and 5.11 is impossible - I keep hitting neverending stream of bugs.
> > > As always with nouveau...
> > 
> > e34b8feeaa4b65725b25f49c9b08a0f8707e8e86 seems to be the first bad commit
> > Going back one commit makes it crash in a different way:
> > 
> > [   55.444208] BUG: kernel NULL pointer dereference, address: 000001b0
> > [   55.444219] #PF: supervisor read access in kernel mode
> > [   55.444222] #PF: error_code(0x0000) - not-present page
> > [   55.444225] *pde = 00000000
> > [   55.444231] Oops: 0000 [#1] SMP
> > [   55.444237] CPU: 0 PID: 1740 Comm: Xorg Not tainted 5.9.0-rc5+ #361
> > [   55.444240] Hardware name:  /848P-ICH5, BIOS 6.00 PG 02/03/2005
> > [   55.444321] EIP: nouveau_bo_wr16+0x8/0x27 [nouveau]
> > [   55.444326] Code: 85 ff 74 0d 80 7d f3 00 74 07 80 a6 f4 01 00 00 fe 89 f0 e8 0c ef ff ff 8d 65 f4 89 f8 5b 5e 5f 5d c3 55 01 d2 89 e5 53 89 c3 <03> 93 b0 01 00 00 0f b7 c1 f6 83 b8 01 00 00 80 74 07 e8 40 49 69
> > [   55.444330] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000000
> > [   55.444334] ESI: 00000020 EDI: e7a14400 EBP: e786fd98 ESP: e786fd94
> > [   55.444338] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00210246
> > [   55.444341] CR0: 80050033 CR2: 000001b0 CR3: 27896000 CR4: 00000690
> > [   55.444344] Call Trace:
> > [   55.444395]  nv04_crtc_cursor_set+0x148/0x1d8 [nouveau]
> > [   55.444442]  ? ttm_bo_reserve.constprop.15+0x1c/0x1c [nouveau]
> > [   55.444451]  drm_mode_cursor_common+0x13b/0x1ad
> > [   55.444497]  ? ttm_bo_reserve.constprop.15+0x1c/0x1c [nouveau]
> > [   55.444504]  drm_mode_cursor_ioctl+0x2e/0x36
> > [   55.444509]  ? drm_mode_setplane+0x203/0x203
> > [   55.444514]  drm_ioctl_kernel+0x66/0x99
> > [   55.444518]  drm_ioctl+0x211/0x2d8
> > [   55.444522]  ? drm_mode_setplane+0x203/0x203
> > [   55.444529]  ? _cond_resched+0x1e/0x22
> > [   55.444533]  ? mutex_lock+0xb/0x24
> > [   55.444582]  ? nouveau_bo_add_io_reserve_lru+0x53/0x58 [nouveau]
> > [   55.444589]  ? rpm_resume.part.13+0x72/0x365
> > [   55.444594]  ? ktime_get_mono_fast_ns+0x5e/0xf2
> > [   55.444598]  ? __pm_runtime_resume+0x5b/0x63
> > [   55.444647]  nouveau_drm_ioctl+0x65/0x81 [nouveau]
> > [   55.444696]  ? nouveau_cli_work+0xc3/0xc3 [nouveau]
> > [   55.444702]  vfs_ioctl+0x1a/0x24
> > [   55.444706]  __ia32_sys_ioctl+0x583/0x59d
> > [   55.444711]  ? doublefault_shim+0x120/0x120
> > [   55.444717]  ? exit_to_user_mode_prepare+0x71/0xba
> > [   55.444721]  do_int80_syscall_32+0x2c/0x39
> > [   55.444725]  entry_INT80_32+0xf0/0xf0
> > [   55.444729] EIP: 0xb7fb2092
> > [   55.444733] Code: 00 00 00 e9 90 ff ff ff ff a3 24 00 00 00 68 30 00 00 00 e9 80 ff ff ff ff a3 e8 ff ff ff 66 90 00 00 00 00 00 00 00 00 cd 80 <c3> 8d b4 26 00 00 00 00 8d b6 00 00 00 00 8b 1c 24 c3 8d b4 26 00
> > [   55.444737] EAX: ffffffda EBX: 0000000e ECX: c01c64a3 EDX: bfe89750
> > [   55.444741] ESI: 02580b40 EDI: c01c64a3 EBP: 0000000e ESP: bfe89704
> > [   55.444744] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00200292
> > [   55.444748] Modules linked in: i2c_dev nouveau serial_cs snd_intel8x0 snd_ac97_codec wmi hwmon ttm ac97_bus 8139cp snd_pcm pcmcia snd_timer snd sg soundcore psmouse yenta_socket serio_raw pcmcia_rsrc pcmcia_core intel_agp parport_pc parport
> > [   55.444769] CR2: 00000000000001b0
> > [   55.444774] ---[ end trace e2b0d4c3c2e4e488 ]---
> > [   55.444827] EIP: nouveau_bo_wr16+0x8/0x27 [nouveau]
> > [   55.444831] Code: 85 ff 74 0d 80 7d f3 00 74 07 80 a6 f4 01 00 00 fe 89 f0 e8 0c ef ff ff 8d 65 f4 89 f8 5b 5e 5f 5d c3 55 01 d2 89 e5 53 89 c3 <03> 93 b0 01 00 00 0f b7 c1 f6 83 b8 01 00 00 80 74 07 e8 40 49 69
> > [   55.444835] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000000
> > [   55.444838] ESI: 00000020 EDI: e7a14400 EBP: e786fd98 ESP: e786fd94
> > [   55.444842] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00210246
> > [   55.444845] CR0: 80050033 CR2: 000001b0 CR3: 27896000 CR4: 00000690
> 
> Bisected this crash:
> # first bad commit: [141b15e59175aa174ca1f7596188bd15a7ca17ba] drm/nouveau: move io_reserve_lru handling into the driver v5
> 
> Adding Christian K?nig to CC.

Tracked it down to an uninitialized variable bug.
I see now that this was fixed by aea656b0d05ec5b8ed5beb2f94c4dd42ea834e9d.

-- 
Ondrej Zary