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

Will Deacon
2019-04-03T11:11:34Z

Hi Michael,

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.

> Ran the io_uring example from fio, which prints lots of:

How did you invoke that? I had a play with the tests in:

git://git.kernel.dk/liburing

but I quickly ran into the kernel oops below.

Will

--->8

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
[ 35.490088] x29: ffff000017e2bbc0 x28: ffff8004b9118000
[ 35.490939] x27: 0000000000000000 x26: ffff8004c21c4200
[ 35.491786] x25: 0000000000000004 x24: ffff00001123e1b0
[ 35.492640] x23: ffff8004c5390000 x22: ffff8004bb440500
[ 35.493502] x21: ffff8004bb440500 x20: 0000000000000070
[ 35.494355] x19: 0000000000000022 x18: 0000000000000000
[ 35.495202] x17: 0000000000000000 x16: 0000000000000000
[ 35.496054] x15: 0000000000000000 x14: ffff7e0012e8a240
[ 35.496910] x13: 00004a73a5e663e2 x12: 0000000000000000
[ 35.497764] x11: 0000000000000001 x10: 0000000000000070
[ 35.498611] x9 : ffff8004cb49d610 x8 : 00000000ffffffff
[ 35.499462] x7 : ffff8004c4ff9c70 x6 : ffff8004cb49ccb0
[ 35.500308] x5 : ffff8004c66cc4c0 x4 : 0000000000000001
[ 35.501173] x3 : 0000000000000000 x2 : 0000000000000040
[ 35.502019] x1 : 0000000000000004 x0 : 0000000000000000
[ 35.502872] Process io_uring_regist (pid: 3973, stack limit = 0x(____ptrval____))
[ 35.504052] Call trace:
[ 35.504463] link_pwq+0x10/0x60
[ 35.504987] apply_wqattrs_commit+0xe0/0x118
[ 35.505681] apply_workqueue_attrs_locked+0x3c/0x80
[ 35.506460] apply_workqueue_attrs+0x3c/0x60
[ 35.507152] alloc_workqueue+0x264/0x430
[ 35.507786] io_uring_setup+0x478/0x6a8
[ 35.508414] __arm64_sys_io_uring_setup+0x18/0x20
[ 35.509183] el0_svc_common+0x80/0xf0
[ 35.509786] el0_svc_handler+0x2c/0x80
[ 35.510393] el0_svc+0x8/0xc
[ 35.510873] Code: a9bd7bfd 910003fd a90153f3 9101c014 (f9403802)
[ 35.511843] ---[ end trace 0a53e45ee26def4c ]---
Segmentation fault