On 2/12/23 6:35 AM, Jens Axboe wrote: > On 2/12/23 6:28?AM, Helge Deller wrote: >> On 2/12/23 14:16, Jens Axboe wrote: >>> On 2/12/23 2:47?AM, Helge Deller wrote: >>>> Hi all, >>>> >>>> We see io-uring failures on the parisc architecture with this testcase: >>>> https://github.com/axboe/liburing/blob/master/examples/io_uring-test.c >>>> >>>> parisc is always big-endian 32-bit userspace, with either 32- or 64-bit kernel. >>>> >>>> On a 64-bit kernel (6.1.11): >>>> deller@parisc:~$ ./io_uring-test test.file >>>> ret=0, wanted 4096 >>>> Submitted=4, completed=1, bytes=0 >>>> -> failure >>>> >>>> strace shows: >>>> io_uring_setup(4, {flags=0, sq_thread_cpu=0, sq_thread_idle=0, sq_entries=4, cq_entries=8, features=IORING_FEAT_SINGLE_MMAP|IORING_FEAT_NODROP|IORING_FEAT_SUBMIT_STABLE|IORING_FEAT_RW_CUR_POS|IORING_FEAT_CUR_PERSONALITY|IORING_FEAT_FAST_POLL|IORING_FEAT_POLL_32BITS|0x1f80, sq_off={head=0, tail=16, ring_mask=64, ring_entries=72, flags=84, dropped=80, array=224}, cq_off={head=32, tail=48, ring_mask=68, ring_entries=76, overflow=92, cqes=96, flags=0x58 /* IORING_CQ_??? */}}) = 3 >>>> mmap2(NULL, 240, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, 3, 0) = 0xf7522000 >>>> mmap2(NULL, 256, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, 3, 0x10000000) = 0xf6922000 >>>> openat(AT_FDCWD, "libell0-dbgsym_0.56-2_hppa.deb", O_RDONLY|O_DIRECT) = 4 >>>> statx(4, "", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT|AT_EMPTY_PATH, STATX_BASIC_STATS, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0644, stx_size=689308, ...}) = 0 >>>> getrandom("\x5c\xcf\x38\x2d", 4, GRND_NONBLOCK) = 4 >>>> brk(NULL) = 0x4ae000 >>>> brk(0x4cf000) = 0x4cf000 >>>> io_uring_enter(3, 4, 0, 0, NULL, 8) = 0 >>>> >>>> >>>> Running the same testcase on a 32-bit kernel (6.1.11) works: >>>> root@debian:~# ./io_uring-test test.file >>>> Submitted=4, completed=4, bytes=16384 >>>> -> ok. >>>> >>>> strace: >>>> io_uring_setup(4, {flags=0, sq_thread_cpu=0, sq_thread_idle=0, sq_entries=4, cq_entries=8, features=IORING_FEAT_SINGLE_MMAP|IORING_FEAT_NODROP|IORING_FEAT_SUBMIT_STABLE|IORING_FEAT_RW_CUR_POS|IORING_FEAT_CUR_PERSONALITY|IORING_FEAT_FAST_POLL|IORING_FEAT_POLL_32BITS|0x1f80, sq_off={head=0, tail=16, ring_mask=64, ring_entries=72, flags=84, dropped=80, array=224}, cq_off={head=32, tail=48, ring_mask=68, ring_entries=76, overflow=92, cqes=96, flags=0x58 /* IORING_CQ_??? */}}) = 3 >>>> mmap2(NULL, 240, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, 3, 0) = 0xf6d4c000 >>>> mmap2(NULL, 256, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_POPULATE, 3, 0x10000000) = 0xf694c000 >>>> openat(AT_FDCWD, "trace.dat", O_RDONLY|O_DIRECT) = 4 >>>> statx(4, "", AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT|AT_EMPTY_PATH, STATX_BASIC_STATS, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0644, stx_size=1855488, ...}) = 0 >>>> getrandom("\xb2\x3f\x0c\x65", 4, GRND_NONBLOCK) = 4 >>>> brk(NULL) = 0x15000 >>>> brk(0x36000) = 0x36000 >>>> io_uring_enter(3, 4, 0, 0, NULL, 8) = 4 >>>> >>>> I'm happy to test any patch if someone has an idea.... >>> >>> No idea what this could be, to be honest. I tried your qemu vm image, >>> and it does boot, but it's missing keys to be able to update apt and >>> install packages... After fiddling with this for 30 min I gave up, any >>> chance you can update the sid image? Given how slow this thing is >>> running, it'd take me all day to do a fresh install and I have to admit >>> I'm not THAT motivated about parisc to do that :) >> >> Yes, I will update that image, but qemu currently only supports a >> 32-bit PA-RISC CPU which can only run the 32-bit kernel. So even if I >> update it, you won't be able to reproduce it, as it only happens with >> the 64-bit kernel. I'm sure it's some kind of missing 32-to-64bit >> translation in the kernel, which triggers only big-endian machines. > > I built my own kernel for it, so that should be fine, correct? We'll see > soon enough, managed to disable enough checks on the debian-10 image to > actually make it install packages. Oh, qemu doesn't support 64-bit parisc... Totally missed that, just had to find out for myself. I know io_uring runs fine on s390 which is big endian iirc, and for io_uring itself, there's no swapping or ordering going on or assumed. So a bit puzzled on what this would be. But: >> I will try to add some printks and compare the output of 32- and >> 64-bit kernels. If you have some suggestion where to add such (which?) >> debug code, it would help me a lot. > > I'd just try: > > echo 1 > /sys/kernel/debug/tracing/events/io_uring This might help shed some light on it for you. -- Jens Axboe
