On 2/12/23 12:35?PM, Helge Deller wrote: > On 2/12/23 15:03, Helge Deller wrote: >> On 2/12/23 14:35, 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? >> >> No, as qemu won't boot the 64-bit kernel. >> >>> We'll see soon enough, managed to disable enough checks on the >>> debian-10 image to actually make it install packages. >>> >>>> Does powerpc with a 64-bit ppc64 kernel work? >>>> I'd assume it will show the same issue. >>> >>> No idea... Only stuff I use and test on is x86-64/32 and arm64. >> >> Would be interesting if someone could test... >> >>>> 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 >> >> I'll try, but will take some time... >> > > At entry of io_submit_sqes(), io_sqring_entries() returns 0, because > ctx->rings->sq.tail is 0 (wrongly on broken 64-bit, but ok value 4 on 32-bit), and > ctx->cached_sq_head is 0 in both cases. cached_sq_head will get updated as sqes are consumed, but since sq.tail is zero, there's nothing to submit as far as io_uring is concerned. Can you dump addresses/offsets of the sq and cq heads/tails in userspace and in the kernel? They are u32, so same size of 32 and 64-bit. -- Jens Axboe
