RE: Linux 5.10-rc4

[David Laight]

From: Thomas Zimmermann
> Sent: 18 November 2020 19:37
> 
> Hi
> 
> Am 18.11.20 um 19:10 schrieb Linus Torvalds:
> > On Wed, Nov 18, 2020 at 4:12 AM David Laight <David.Laight@xxxxxxxxxx> wrote:
> >>
> >> I've got the 'splat' below during boot.
> >> This is an 8-core C2758 Atom cpu using the on-board/cpu graphics.
> >> User space is Ubuntu 20.04.
> >>
> >> Additionally the X display has all the colours and alignment slightly
> >> messed up.
> >> 5.9.0 was ok.
> >> I'm just guessing the two issues are related.
> >
> > Sounds likely.  But it would be lovely if you could bisect when
> > exactly the problem(s) started to both verify that, and just to
> > pinpoint the exact change..

I don't quite understand what 'git bisect' did.
I was bisecting between v5.9 and v5.10-rc1 but it suddenly started
generating v5.9.0-rc5+ kernels.

The identified commit was 13a8f46d803 drm/ttm: move ghost object created.
(retyped - hope it is right).
But the diff to that last 'good' commit is massive.

So I don't know if that is anywhere near right.

	David

> >
> > I'm adding Thomas Zimmermann to the cc, because he did that "drm/ast:
> > Program display mode in CRTC's atomic_enable" which looks relevant in
> > that it's right in that call-chain.
> >
> > Did some initialization perhaps get overlooked?
> >
> > And Dave and Daniel and the drm list cc'd as well..
> >
> > Full splat left quoted below for new people and list.
> >
> >              Linus
> >
> >> [   20.809891] WARNING: CPU: 0 PID: 973 at drivers/gpu/drm/drm_gem_vram_helper.c:284
> drm_gem_vram_offset+0x35/0x40 [drm_vram_helper]
> 
> That line is at [1], which comes from
> 
>   46642a7d4d80 ("drm/vram-helper: don't use ttm bo->offset v4")
> 
> But the patch was merged in 5.9-rc1, so it's probably something else.
> 
> We've had a lot of TTM-related changes recently, so my best guess is
> that it's something in TTM with BO initialization.
> 
>  From some grepping, it looks like we have to call ttm_bo_mem_space() to
> fill mm_node (i.e., the pointer that causes the warning). But I cannot
> find where vram helpers do this. Maybe that's a good starting point.
> 
> I'm adding the TTM devs to cc.
> 
> Best regards
> Thomas
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/drm_gem_vram_h
> elper.c?h=v5.10-rc4#n284
> 
> 
> >> [   20.821543] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua
> ipmi_ssif intel_powerclamp coretemp kvm_intel kvm joydev input_leds ipmi_si intel_cstate ipmi_devintf
> ipmi_msghandler mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 btrfs
> blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor
> async_tx libcrc32c xor raid6_pq raid1 raid0 multipath linear ast drm_vram_helper drm_kms_helper
> syscopyarea sysfillrect sysimgblt fb_sys_fops cec drm_ttm_helper ttm crct10dif_pclmul crc32_pclmul
> ghash_clmulni_intel gpio_ich drm aesni_intel hid_generic glue_helper crypto_simd igb usbhid cryptd
> ahci i2c_i801 hid libahci i2c_smbus lpc_ich dca i2c_ismt i2c_algo_bit
> >> [   20.887477] CPU: 0 PID: 973 Comm: gnome-shell Not tainted 5.10.0-rc4+ #78
> >> [   20.894274] Hardware name: Supermicro A1SAi/A1SRi, BIOS 1.1a 08/27/2015
> >> [   20.900896] RIP: 0010:drm_gem_vram_offset+0x35/0x40 [drm_vram_helper]
> >> [   20.907342] Code: 00 48 89 e5 85 c0 74 17 48 83 bf 78 01 00 00 00 74 18 48 8b 87 80 01 00 00 5d
> 48 c1 e0 0c c3 0f 0b 48 c7 c0 ed ff ff ff 5d c3 <0f> 0b 31 c0 5d c3 0f 1f 44 00 00 0f 1f 44 00 00 55
> 48 8b 87 18 06
> >> [   20.926100] RSP: 0018:ffff9f59811d3a68 EFLAGS: 00010246
> >> [   20.931339] RAX: 0000000000000002 RBX: ffff8b46861e20c0 RCX: ffffffffc032d600
> >> [   20.938479] RDX: ffff8b468f47a000 RSI: ffff8b46861e2000 RDI: ffff8b468f9acc00
> >> [   20.945622] RBP: ffff9f59811d3a68 R08: 0000000000000040 R09: ffff8b46864ce288
> >> [   20.952769] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8b468f47a000
> >> [   20.959915] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8b468ad2bf00
> >> [   20.967057] FS:  00007f5b37ac5cc0(0000) GS:ffff8b49efc00000(0000) knlGS:0000000000000000
> >> [   20.975149] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> [   20.980904] CR2: 00007f5b3d093f00 CR3: 0000000103438000 CR4: 00000000001006f0
> >> [   20.988047] Call Trace:
> >> [   20.990506]  ast_cursor_page_flip+0x22/0x100 [ast]
> >> [   20.995313]  ast_cursor_plane_helper_atomic_update+0x46/0x70 [ast]
> >> [   21.001524]  drm_atomic_helper_commit_planes+0xbd/0x220 [drm_kms_helper]
> >> [   21.008243]  drm_atomic_helper_commit_tail_rpm+0x3a/0x70 [drm_kms_helper]
> >> [   21.015062]  commit_tail+0x99/0x130 [drm_kms_helper]
> >> [   21.020050]  drm_atomic_helper_commit+0x123/0x150 [drm_kms_helper]
> >> [   21.026269]  drm_atomic_commit+0x4a/0x50 [drm]
> >> [   21.030737]  drm_atomic_helper_update_plane+0xe7/0x140 [drm_kms_helper]
> >> [   21.037384]  __setplane_atomic+0xcc/0x110 [drm]
> >> [   21.041953]  drm_mode_cursor_universal+0x13e/0x260 [drm]
> >> [   21.047299]  drm_mode_cursor_common+0xef/0x220 [drm]
> >> [   21.052287]  ? alloc_set_pte+0x10d/0x6d0
> >> [   21.056244]  ? drm_mode_cursor_ioctl+0x60/0x60 [drm]
> >> [   21.061242]  drm_mode_cursor2_ioctl+0xe/0x10 [drm]
> >> [   21.066067]  drm_ioctl_kernel+0xae/0xf0 [drm]
> >> [   21.070455]  drm_ioctl+0x241/0x3f0 [drm]
> >> [   21.074415]  ? drm_mode_cursor_ioctl+0x60/0x60 [drm]
> >> [   21.079401]  __x64_sys_ioctl+0x91/0xc0
> >> [   21.083167]  do_syscall_64+0x38/0x90
> >> [   21.086755]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >> [   21.091813] RIP: 0033:0x7f5b3cf1350b
> >> [   21.095403] Code: 0f 1e fa 48 8b 05 85 39 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66
> 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 55 39 0d 00 f7
> d8 64 89 01 48
> >> [   21.114154] RSP: 002b:00007ffef1966588 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >> [   21.121730] RAX: ffffffffffffffda RBX: 00007ffef19665c0 RCX: 00007f5b3cf1350b
> >> [   21.128870] RDX: 00007ffef19665c0 RSI: 00000000c02464bb RDI: 0000000000000009
> >> [   21.136013] RBP: 00000000c02464bb R08: 0000000000000040 R09: 0000000000000004
> >> [   21.143157] R10: 0000000000000002 R11: 0000000000000246 R12: 0000561ec9d10060
> >> [   21.150295] R13: 0000000000000009 R14: 0000561eca2cc9a0 R15: 0000000000000040
> 
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer

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