Re: [PATCH 2/2] arch: add pidfd and io_uring syscalls everywhere

Michael Ellerman
2019-04-04T06:08:59Z

Jens Axboe <axboe@kernel.dk> writes:
> On 4/3/19 5:11 AM, Will Deacon wrote:
>> On Wed, Apr 03, 2019 at 01:47:50PM +1100, Michael Ellerman wrote:
>>> Arnd Bergmann <arnd@arndb.de> writes:
>>>> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
>>>> index b18abb0c3dae..00f5a63c8d9a 100644
>>>> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
>>>> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
>>>> @@ -505,3 +505,7 @@
>>>> 421 32 rt_sigtimedwait_time64 sys_rt_sigtimedwait compat_sys_rt_sigtimedwait_time64
>>>> 422 32 futex_time64 sys_futex sys_futex
>>>> 423 32 sched_rr_get_interval_time64 sys_sched_rr_get_interval sys_sched_rr_get_interval
>>>> +424 common pidfd_send_signal sys_pidfd_send_signal
>>>> +425 common io_uring_setup sys_io_uring_setup
>>>> +426 common io_uring_enter sys_io_uring_enter
>>>> +427 common io_uring_register sys_io_uring_register
>>>
>>> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
>>>
>>> Lightly tested.
>>>
>>> The pidfd_test selftest passes.
>>
>> That reports pass for me too, although it fails to unshare the pid ns, which I
>> assume is benign.

If you run it as root it should work?

>>> Ran the io_uring example from fio, which prints lots of:
>>
>> How did you invoke that? I had a play with the tests in:
>
> It's t/io_uring from the fio repo:
>
> git://git.kernel.dk/fio
>
> and you just run it ala:
>
> # make t/io_uring
> # t/io_uring /dev/some_device

Yeah that's all I did.

>> will@autoplooker:~/liburing/test$ ./io_uring_register
>> RELIMIT_MEMLOCK: 67108864 (67108864)
>> [ 35.477875] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070
>> [ 35.478969] Mem abort info:
>> [ 35.479296] ESR = 0x96000004
>> [ 35.479785] Exception class = DABT (current EL), IL = 32 bits
>> [ 35.480528] SET = 0, FnV = 0
>> [ 35.480980] EA = 0, S1PTW = 0
>> [ 35.481345] Data abort info:
>> [ 35.481680] ISV = 0, ISS = 0x00000004
>> [ 35.482267] CM = 0, WnR = 0
>> [ 35.482618] user pgtable: 4k pages, 48-bit VAs, pgdp = (____ptrval____)
>> [ 35.483486] [0000000000000070] pgd=0000000000000000
>> [ 35.484041] Internal error: Oops: 96000004 [#1] PREEMPT SMP
>> [ 35.484788] Modules linked in:
>> [ 35.485311] CPU: 113 PID: 3973 Comm: io_uring_regist Not tainted 5.1.0-rc3-00012-g40b114779944 #1
>> [ 35.486712] Hardware name: linux,dummy-virt (DT)
>> [ 35.487450] pstate: 20400005 (nzCv daif +PAN -UAO)
>> [ 35.488228] pc : link_pwq+0x10/0x60
>> [ 35.488794] lr : apply_wqattrs_commit+0xe0/0x118
>> [ 35.489550] sp : ffff000017e2bbc0
>
> Huh, this looks odd, it's crashing inside the wq setup.

Looks like you found a bug :)

cheers