Message-ID: <b85e2210-b56e-c01d-9320-8c120e89498c@suse.de>
Date:   Thu, 31 Mar 2022 09:02:57 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:     Javier Martinez Canillas <javierm@...hat.com>,
        Zack Rusin <zackr@...are.com>,
        Hans de Goede <hdegoede@...hat.com>,
        torvalds@...ux-foundation.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: regression: NULL pointer dereference due to 27599aacbaef ("fbdev:
 Hot-unplug firmware fb devices on forced removal")

Hi

Am 28.03.22 um 17:41 schrieb Sudip Mukherjee:
> Hi Thomas,
> 
> We usually run boot tests with linux mainline HEAD commit almost every
> night on ppc64 qemu. And my tests had been failing for last few days.

Thanks for reporting. I'll take a look soon.

Best regards
Thomas

> Testing locally gave me:
> 
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.038791] BUG: Kernel NULL pointer dereference on read at 0x00000060
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.038995] Faulting instruction address: 0xc00000000080dfa4
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.039572] Oops: Kernel access of bad area, sig: 11 [#1]
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.039723] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.040012] Modules linked in: bochs(+) drm_vram_helper xhci_pci drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm_ttm_helper sr_mod ttm cdrom xhci_hcd virtio_net virtio_console net_failover virtio_blk virtio_scsi failover ibmvscsi scsi_transport_srp virtio_pci virtio virtio_pci_legacy_dev virtio_pci_modern_dev usbcore drm drm_panel_orientation_quirks virtio_ring usb_common
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.040918] CPU: 2 PID: 139 Comm: systemd-udevd Not tainted 5.17.0-ae085d7f9365 #1
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.041245] NIP:  c00000000080dfa4 LR: c00000000080df9c CTR: c000000000797430
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.041376] REGS: c000000004132fe0 TRAP: 0300   Not tainted  (5.17.0-ae085d7f9365)
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.041528] MSR:  8000000002009033 <SF,VEC,EE,ME,IR,DR,RI,LE>  CR: 28228282  XER: 20000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] CFAR: c00000000000c80c DAR: 0000000000000060 DSISR: 40000000 IRQMASK: 0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR00: c00000000080df9c c000000004133280 c00000000169d200 0000000000000029
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR04: 00000000ffffefff c000000004132f90 c000000004132f88 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR08: c0000000015658f8 c0000000015cd200 c0000000014f57d0 0000000048228283
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR12: 0000000000000000 c00000003fffe300 0000000020000000 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR16: 0000000000000000 0000000113fc4a40 0000000000000005 0000000113fcfb80
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR20: 000001000f7283b0 0000000000000000 c000000000e4a588 c000000000e4a5b0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR24: 0000000000000001 00000000000a0000 c008000000db0168 c0000000021f6ec0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.042017] GPR28: c0000000016d65a8 c000000004b36460 0000000000000000 c0000000016d64b0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.043184] NIP [c00000000080dfa4] do_remove_conflicting_framebuffers+0x184/0x1d0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.043748] LR [c00000000080df9c] do_remove_conflicting_framebuffers+0x17c/0x1d0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.043982] Call Trace:
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.044108] [c000000004133280] [c00000000080df9c] do_remove_conflicting_framebuffers+0x17c/0x1d0 (unreliable)
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.044335] [c000000004133350] [c00000000080e4d0] remove_conflicting_framebuffers+0x60/0x150
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.044468] [c0000000041333a0] [c00000000080e6f4] remove_conflicting_pci_framebuffers+0x134/0x1b0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.044588] [c000000004133450] [c008000000e70438] drm_aperture_remove_conflicting_pci_framebuffers+0x90/0x100 [drm]
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.045443] [c000000004133490] [c008000000da0ce4] bochs_pci_probe+0x6c/0xa64 [bochs]
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.045624] [c000000004133570] [c0000000007ca518] local_pci_probe+0x68/0x110
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.045730] [c0000000041335f0] [c0000000007cb438] pci_call_probe+0x88/0x1a0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.045830] [c000000004133750] [c0000000007cc6ac] pci_device_probe+0xbc/0x1a0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.045928] [c000000004133790] [c0000000008969e0] really_probe+0x100/0x5e0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046025] [c000000004133810] [c00000000089704c] __driver_probe_device+0x18c/0x250
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046125] [c000000004133890] [c00000000089716c] driver_probe_device+0x5c/0x140
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046225] [c0000000041338d0] [c000000000897cf8] __driver_attach+0x118/0x290
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046322] [c000000004133950] [c000000000892d38] bus_for_each_dev+0xa8/0x130
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046425] [c0000000041339b0] [c000000000895c24] driver_attach+0x34/0x50
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046521] [c0000000041339d0] [c000000000895308] bus_add_driver+0x1b8/0x2e0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046618] [c000000004133a60] [c000000000898ea4] driver_register+0xb4/0x1c0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046714] [c000000004133ad0] [c0000000007c9d28] __pci_register_driver+0x68/0x80
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046815] [c000000004133af0] [c008000000da174c] bochs_pci_driver_init+0x70/0x98 [bochs]
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.046931] [c000000004133b20] [c000000000011fd0] do_one_initcall+0x60/0x2d0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.047033] [c000000004133c00] [c000000000229d38] do_init_module+0x68/0x360
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.047136] [c000000004133c90] [c00000000022dc3c] __do_sys_finit_module+0xdc/0x180
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.047239] [c000000004133db0] [c00000000002aaa0] system_call_exception+0x170/0x2d0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.050839] [c000000004133e10] [c00000000000c3cc] system_call_common+0xec/0x250
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.053127] --- interrupt: c00 at 0x7fffa43100c4
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.055616] NIP:  00007fffa43100c4 LR: 00007fffa457fe2c CTR: 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.058073] REGS: c000000004133e80 TRAP: 0c00   Not tainted  (5.17.0-ae085d7f9365)
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.060563] MSR:  800000000000f033 <SF,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 24222824  XER: 00000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] IRQMASK: 0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR00: 0000000000000161 00007fffe8930710 00007fffa43f7100 0000000000000015
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR04: 00007fffa458b448 0000000000000000 0000000000000000 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR12: 0000000000000000 00007fffa465ddd0 0000000020000000 0000000000000000
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR16: 0000000000000000 0000000113fc4a40 0000000000000005 0000000113fcfb80
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR20: 000001000f7283b0 0000000000000000 0000000113fcfb68 000001000f729570
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR24: 0000000000000000 000001000f7283b0 0000000000020000 000001000f7282f0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.063048] GPR28: 00007fffa458b448 0000000000020000 0000000000000000 000001000f7283b0
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.086658] NIP [00007fffa43100c4] 0x7fffa43100c4
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.091853] LR [00007fffa457fe2c] 0x7fffa457fe2c
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.097294] --- interrupt: c00
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.103124] Instruction dump:
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.112912] 7d710120 7d708120 4e800020 e8df0000 7fc407b4 7f45d378 7ec3b378 f8810068
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.119165] 38c600f0 4b9b9c7d 60000000 3d22fff3 <e9550060> 392979e8 e8810068 7c2a4800
> Mar 28 13:16:36 debian-ppc64 kernel: [   11.123573] ---[ end trace 0000000000000000 ]---
> 
> My last good test was with 5.17.0-3bf03b9a0839 and can be seen at:
> https://openqa.qa.codethink.co.uk/tests/932
> 
> A failure test with 5.17.0-52d543b5497c can be seen at: https://openqa.qa.codethink.co.uk/tests/937
> 
> After reverting 27599aacbaef ("fbdev: Hot-unplug firmware fb devices on
> forced removal") on top of latest Linux mainline HEAD fixes the problem
> and I can see qemu booting again.
> 
> I will be happy to test any patch fixing the problem.
> 
> 
> --
> Regards
> Sudip

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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