Re: [BUG BISECT] Ethernet fail on VF50 (OF: Don't set default coherent DMA mask)

[Robin Murphy]

On 28/07/18 17:58, Guenter Roeck wrote:
> On Fri, Jul 27, 2018 at 04:04:48PM +0200, Christoph Hellwig wrote:
> > On Fri, Jul 27, 2018 at 03:18:14PM +0200, Krzysztof Kozlowski wrote:
> > > On 27 July 2018 at 15:11, Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> > > > Hi,
> > > >
> > > > On today's next, the bisect pointed commit
> > > > ff33d1030a6ca87cea9a41e1a2ea7750a781ab3d as fault for my boot failures
> > > > with NFSv4 root on Toradex Colibri VF50 (Iris carrier board).
> > > >
> > > > Author: Robin Murphy <robin.murphy@xxxxxxx>
> > > > Date:   Mon Jul 23 23:16:12 2018 +0100
> > > >      OF: Don't set default coherent DMA mask
> > > >
> > > > Board: Toradex Colibri VF50 (NXP VF500, Cortex A5, serial configured
> > > > with DMA) on Iris Carrier.
> > > >
> > > > It looks like problem with Freescale Ethernet driver:
> > > > [   15.458477] fsl-edma 40018000.dma-controller: coherent DMA mask is unset
> > > > [   15.465284] fsl-lpuart 40027000.serial: Cannot prepare cyclic DMA
> > > > [   15.472086] Root-NFS: no NFS server address
> > > > [   15.476359] VFS: Unable to mount root fs via NFS, trying floppy.
> > > > [   15.484228] VFS: Cannot open root device "nfs" or
> > > > unknown-block(2,0): error -6
> > > > [   15.491664] Please append a correct "root=" boot option; here are
> > > > the available partitions:
> > > > [   15.500188] 0100           16384 ram0
> > > > [   15.500200]  (driver?)
> > > > [   15.506406] Kernel panic - not syncing: VFS: Unable to mount root
> > > > fs on unknown-block(2,0)
> > > > [   15.514747] ---[ end Kernel panic - not syncing: VFS: Unable to
> > > > mount root fs on unknown-block(2,0) ]---
> > > >
> > > > Attached - defconfig and full boot log.
> > > >
> > > > Any hints?
> > > > Let me know if you need any more information.
> > >
> > > My Exynos boards also fail to boot on missing network:
> > > https://krzk.eu/#/builders/21/builds/799/steps/10/logs/serial0
> > >
> > > As expected there are plenty of "DMA mask not set" warnings... and
> > > later dwc3 driver fails with:
> > >      dwc3: probe of 12400000.dwc3 failed with error -12
> > > which is probably the answer why LAN attached to USB is not present.
> >
> > Looks like all the drivers failed to set a dma mask and were lucky.
>
> I would call it a serious regression. Also, no longer setting a default
> coherent DMA mask is a quite substantial behavioral change, especially
> if and since the code worked just fine up to now.

To reiterate, that particular side-effect was an unintentional 
oversight, and I was simply (un)lucky enough that none of the drivers I 
did test depended on that default mask. Sorry for the blip; please check 
whether it's now fixed in next-20180730 as it should be.

> Crash when booting sam460ex attached below, as is a bisect log.

Nevertheless, like most of the others that came out of the woodwork, 
that appears to be a crash due to a broken cleanup path down the line 
from dma_alloc_coherent() returning NULL - that warrants fixing (or just 
removing) in its own right, because cleanup code which has never been 
tested and doesn't actually work is little more than a pointless waste 
of space.

Robin.

> Guenter
>
> ---
> irq: type mismatch, failed to map hwirq-0 for interrupt-controller3!
> WARNING: CPU: 0 PID: 1 at ppc4xx_msi_probe+0x2dc/0x3b8
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.18.0-rc6-00010-gff33d1030a6c #1
> NIP:  c001c460 LR: c001c29c CTR: 00000000
> REGS: cf82db60 TRAP: 0700   Not tainted  (4.18.0-rc6-00010-gff33d1030a6c)
> MSR:  00029000 <CE,EE,ME>  CR: 24002028  XER: 00000000
>
> GPR00: c001c29c cf82dc10 cf828000 d1021000 d1021000 cf882108 cf82db78 00000000
> GPR08: 00000000 c0377ae4 00000000 1000051b 24002028 00000000 c00025e8 00000000
> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 c0492380 0000004a
> GPR24: 00029000 0000000c 10000000 cf8de410 c0494d60 00029000 cf8bebc0 cf8de400
> NIP [c001c460] ppc4xx_msi_probe+0x2dc/0x3b8
> LR [c001c29c] ppc4xx_msi_probe+0x118/0x3b8
> Call Trace:
> [cf82dc10] [c001c29c] ppc4xx_msi_probe+0x118/0x3b8 (unreliable)
> [cf82dc70] [c0209fbc] platform_drv_probe+0x40/0x9c
> [cf82dc90] [c0208240] driver_probe_device+0x2a8/0x350
> [cf82dcc0] [c0206204] bus_for_each_drv+0x60/0xac
> [cf82dcf0] [c0207e88] __device_attach+0xe8/0x160
> [cf82dd20] [c02071e0] bus_probe_device+0xa0/0xbc
> [cf82dd40] [c02050c8] device_add+0x404/0x5c4
> [cf82dd90] [c0288978] of_platform_device_create_pdata+0x88/0xd8
> [cf82ddb0] [c0288b70] of_platform_bus_create+0x134/0x220
> [cf82de10] [c0288bcc] of_platform_bus_create+0x190/0x220
> [cf82de70] [c0288cf4] of_platform_bus_probe+0x98/0xec
> [cf82de90] [c0449650] __machine_initcall_canyonlands_ppc460ex_device_probe+0x38/0x54
> [cf82dea0] [c0002404] do_one_initcall+0x40/0x188
> [cf82df00] [c043daec] kernel_init_freeable+0x130/0x1d0
> [cf82df30] [c0002600] kernel_init+0x18/0x104
> [cf82df40] [c000c23c] ret_from_kernel_thread+0x14/0x1c
> Instruction dump:
> 3860000e 4bffa2a5 3860000f 7f44d378 4bffa299 4bfffe30 3860000e 4bffa28d
> 3860000f 7f24cb78 4bffa281 4bfffde4 <0fe00000> 81290000 2f890000 409efe6c
> ---[ end trace 8cf551077ecfc429 ]---
> ppc4xx-msi c10000000.ppc4xx-msi: coherent DMA mask is unset
> Unable to handle kernel paging request for data at address 0x00000000
> Faulting instruction address: 0xc001bff0
> Oops: Kernel access of bad area, sig: 11 [#1]
> BE Canyonlands
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Tainted: G        W         4.18.0-rc6-00010-gff33d1030a6c #1
> NIP:  c001bff0 LR: c001c418 CTR: c01faa7c
> REGS: cf82db40 TRAP: 0300   Tainted: G        W          (4.18.0-rc6-00010-gff33d1030a6c)
> MSR:  00029000 <CE,EE,ME>  CR: 28002024  XER: 00000000
> DEAR: 00000000 ESR: 00000000
> GPR00: c001c418 cf82dbf0 cf828000 cf8de400 00000000 00000000 000000c4 000000c4
> GPR08: c0481ea4 00000000 00000000 000000c4 22002024 00000000 c00025e8 00000000
> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 c0492380 0000004a
> GPR24: 00029000 0000000c 00000000 cf8de410 c0494d60 c0494d60 cf8bebc0 00000001
> NIP [c001bff0] ppc4xx_of_msi_remove+0x48/0xa0
> LR [c001c418] ppc4xx_msi_probe+0x294/0x3b8
> Call Trace:
> [cf82dbf0] [00029000] 0x29000 (unreliable)
> [cf82dc10] [c001c418] ppc4xx_msi_probe+0x294/0x3b8
> [cf82dc70] [c0209fbc] platform_drv_probe+0x40/0x9c
> [cf82dc90] [c0208240] driver_probe_device+0x2a8/0x350
> [cf82dcc0] [c0206204] bus_for_each_drv+0x60/0xac
> [cf82dcf0] [c0207e88] __device_attach+0xe8/0x160
> [cf82dd20] [c02071e0] bus_probe_device+0xa0/0xbc
> [cf82dd40] [c02050c8] device_add+0x404/0x5c4
> [cf82dd90] [c0288978] of_platform_device_create_pdata+0x88/0xd8
> [cf82ddb0] [c0288b70] of_platform_bus_create+0x134/0x220
> [cf82de10] [c0288bcc] of_platform_bus_create+0x190/0x220
> [cf82de70] [c0288cf4] of_platform_bus_probe+0x98/0xec
> [cf82de90] [c0449650] __machine_initcall_canyonlands_ppc460ex_device_probe+0x38/0x54
> [cf82dea0] [c0002404] do_one_initcall+0x40/0x188
> [cf82df00] [c043daec] kernel_init_freeable+0x130/0x1d0
> [cf82df30] [c0002600] kernel_init+0x18/0x104
> [cf82df40] [c000c23c] ret_from_kernel_thread+0x14/0x1c
> Instruction dump:
> 90010024 813d0024 2f890000 83c30058 41bd0014 48000038 813d0024 7f89f800
> 409d002c 813e000c 57ea103a 3bff0001 <7c69502e> 2f830000 419effe0 4803b26d
> ---[ end trace 8cf551077ecfc42a ]---
>
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>
> ---
> # bad: [639d109b21f1413c54ca7042e40a57856e7679bb] Add linux-next specific files for 20180727
> # good: [d72e90f33aa4709ebecc5005562f52335e106a60] Linux 4.18-rc6
> git bisect start 'HEAD' 'v4.18-rc6'
> # bad: [7bc81125a936a25af28f2172b593bca390b0c539] Merge remote-tracking branch 'spi-nor/spi-nor/next'
> git bisect bad 7bc81125a936a25af28f2172b593bca390b0c539
> # bad: [659868e6488dbad1181ad21888521ff41ae45f65] Merge remote-tracking branch 'vfs/for-next'
> git bisect bad 659868e6488dbad1181ad21888521ff41ae45f65
> # bad: [453ff4bb24c3fa4af40995f2615ec22176e71500] Merge remote-tracking branch 'mvebu/for-next'
> git bisect bad 453ff4bb24c3fa4af40995f2615ec22176e71500
> # good: [ebc949ee3c7e28b6554f00fcdaf2c0c8aae54d90] Merge branch 'next/soc' into for-next
> git bisect good ebc949ee3c7e28b6554f00fcdaf2c0c8aae54d90
> # good: [fef31ecbe2ecbb518ad1db37282eb97ca6dd29b8] Merge remote-tracking branch 'leaks/leaks-next'
> git bisect good fef31ecbe2ecbb518ad1db37282eb97ca6dd29b8
> # good: [53b9c41f0d9c35e41ea884bae6ad4b6fadc59035] Merge branch 'next/drivers' into for-next
> git bisect good 53b9c41f0d9c35e41ea884bae6ad4b6fadc59035
> # bad: [cd67b2d4c0ca61f7e93e622dba0164fb176975b4] Merge remote-tracking branch 'arm-soc/for-next'
> git bisect bad cd67b2d4c0ca61f7e93e622dba0164fb176975b4
> # good: [a0c166140d2e63a069263b6d3c39a42c61749d96] Merge branch 'next/drivers' into for-next
> git bisect good a0c166140d2e63a069263b6d3c39a42c61749d96
> # bad: [e5e08751da47170e6a05c09364595ec1abad7cec] Merge remote-tracking branch 'arm/for-next'
> git bisect bad e5e08751da47170e6a05c09364595ec1abad7cec
> # good: [52e19c3c1eaf103c2eb4f764825136abcfea1538] Merge branches 'clkdev', 'fixes', 'misc' and 'spectre' into for-next
> git bisect good 52e19c3c1eaf103c2eb4f764825136abcfea1538
> # good: [e8d4162413ecbf3b3d1451808bdbd212cec8b70c] ACPI/IORT: Set bus DMA mask as appropriate
> git bisect good e8d4162413ecbf3b3d1451808bdbd212cec8b70c
> # good: [186e2e8cc462aed36cc6845c938547833377582f] ACPI/IORT: Don't set default coherent DMA mask
> git bisect good 186e2e8cc462aed36cc6845c938547833377582f
> # bad: [deff076d4ce359c2d83983a75765b4ac8f635d2f] Merge remote-tracking branch 'dma-mapping/for-next'
> git bisect bad deff076d4ce359c2d83983a75765b4ac8f635d2f
> # bad: [ff33d1030a6ca87cea9a41e1a2ea7750a781ab3d] OF: Don't set default coherent DMA mask
> git bisect bad ff33d1030a6ca87cea9a41e1a2ea7750a781ab3d
> # first bad commit: [ff33d1030a6ca87cea9a41e1a2ea7750a781ab3d] OF: Don't set default coherent DMA mask