Re: arm64: 4.14 of_match_node() issues

[Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>]

On 09/10/17 10:24, Will Deacon wrote:
> Hi Andreas,
> 
> On Sat, Oct 07, 2017 at 02:42:13AM +0200, Andreas Färber wrote:
>> Since 4.14-rc1 I am seeing frequent oopses during module loading (e.g.,
>> MMC, USB) from initrd on aarch64. Symptoms are similar to this in -rc3:
>>
>> [  OK  ] Started udev Coldplug all Devices.
>> [   10.117775] usbcore: registered new interface driver usbfs
>> [   10.118235] Unable to handle kernel paging request at virtual address
>> ffff000008e5abc0
>> [   10.118238] Mem abort info:
>> [   10.118245]   Exception class = DABT (current EL), IL = 32 bits
>> [   10.118249]   SET = 0, FnV = 0
>> [   10.118253]   EA = 0, S1PTW = 0
>> [   10.118256] Data abort info:
>> [   10.118261]   ISV = 0, ISS = 0x00000006
>> [   10.118264]   CM = 0, WnR = 0
>> [   10.118274] swapper pgtable: 4k pages, 48-bit VAs, pgd = ffff0000094a5000
>> [   10.118279] [ffff000008e5abc0] *pgd=00000000bfffe003,
>> *pud=00000000bfffd003, *pmd=0000000000000000
>> [   10.118299] Internal error: Oops: 96000006 [#1] SMP
>> [   10.118305] Modules linked in: fixed usbcore(+) sunxi_mmc mmc_core
>> phy_sun4i_usb sg
>> [   10.118341] CPU: 3 PID: 49 Comm: kworker/3:1 Not tainted
>> 4.14.0-rc3-2.gf27997b-default #1
>> [   10.118345] Hardware name: sunxi sunxi/sunxi, BIOS 2017.05-rc1 04/13/2017
>> [   10.118369] Workqueue: events deferred_probe_work_func
>> [   10.118378] task: ffff80007c8f4000 task.stack: ffff0000099d8000
>> [   10.118394] PC is at __of_match_node.part.1+0x48/0x88
>> [   10.118403] LR is at of_match_node+0x40/0x70
>> [   10.118411] pc : [<ffff00000879aed0>] lr : [<ffff00000879af50>]
> 
> [...]
> 
>> This has been observed on Pine64 (>60%; also by Stefan) and Odroid-C2;
>> my other arm64 boards such as Raspberry Pi 3 have not run into this so
>> far. No such problems on 32-bit boards.
>>
>> This is using the openSUSE config:
>> https://kernel.opensuse.org/cgit/kernel-source/plain/config/arm64/default
> 
> Hmm, hard to know what to suggest without a concrete reproducer. Do you know
> which driver is being probed in the log above? Also, does this still break
> if you pass "keepinitrd" on the cmdline? Finally, can you dump the kernel
> virtual memory layout, please?

FWIW, this looks a lot like what happens when a built-in driver's
of_match_table is marked __init, but for whatever reason (deferred probe
etc.) winds up getting poked by a module load after it no longer exists.

Robin.
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