On Tue, Aug 11, 2020 at 07:10:30AM -0600, Jens Axboe wrote: > On 8/11/20 1:05 AM, Dave Chinner wrote: > > On Mon, Aug 10, 2020 at 08:19:57PM -0600, Jens Axboe wrote: > >> On 8/10/20 8:00 PM, Dave Chinner wrote: > >>> On Mon, Aug 10, 2020 at 07:08:59PM +1000, Dave Chinner wrote: > >>>> On Mon, Aug 10, 2020 at 05:08:07PM +1000, Dave Chinner wrote: > >>>>> [cc Jens] > >>>>> > >>>>> [Jens, data corruption w/ io_uring and simple fio reproducer. see > >>>>> the bz link below.] > >>> > >>> Looks like a io_uring/fio bugs at this point, Jens. All your go fast > >>> bits turns the buffered read into a short read, and neither fio nor > >>> io_uring async buffered read path handle short reads. Details below. > >> > >> It's a fio issue. The io_uring engine uses a different path for short > >> IO completions, and that's being ignored by the backend... Hence the > >> IO just gets completed and not retried for this case, and that'll then > >> trigger verification as if it did complete. I'm fixing it up. > > > > I just updated fio to: > > > > cb7d7abb (HEAD -> master, origin/master, origin/HEAD) io_u: set io_u->verify_offset in fill_io_u() > > > > The workload still reports corruption almost instantly. Only this > > time, the trace is not reporting a short read. > > > > File is patterned with: > > > > verify_pattern=0x33333333%o-16 > > > > Offset of "bad" data is 0x1240000. > > > > Expected: > > > > 00000000: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000010: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000020: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000030: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000040: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000050: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000060: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000070: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000080: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > ..... > > 0000ffd0: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 0000ffe0: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 0000fff0: 33 33 33 33 00 10 24 01 00 00 00 00 f0 ff ff ff 3333............ > > > > > > Received: > > > > 00000000: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000010: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000020: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000030: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000040: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000050: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000060: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000070: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 00000080: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > ..... > > 0000ffd0: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 0000ffe0: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > 0000fff0: 33 33 33 33 00 00 24 01 00 00 00 00 f0 ff ff ff 3333............ > > > > > > Looks like the data in the expected buffer is wrong - the data > > pattern in the received buffer is correct according the defined > > pattern. > > > > Error is 100% reproducable from the same test case. Same bad byte in > > the expected buffer dump every single time. > > What job file are you running? It's not impossible that I broken > something else in fio, the io_u->verify_offset is a bit risky... I'll > get it fleshed out shortly. Details are in the bugzilla I pointed you at. I modified the original config specified to put per-file and offset identifiers into the file data rather than using random data. This is "determining the origin of stale data 101" stuff - the first thing we _always_ do when trying to diagnose data corruption is identify where the bad data came from. Entire config file is below. CHeers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx [global] directory=/mnt/scratch size=256M iodepth=16 bs=64k verify=crc32c verify_fatal=1 verify_dump=1 verify=pattern thread=1 loops=200 #direct=1 #unlink=1 buffered=1 [uring_w] rw=randwrite ioengine=io_uring hipri=0 fixedbufs=0 registerfiles=0 sqthread_poll=0 verify_pattern=0x11111111%o-16 [uring_sqt_w] rw=randwrite ioengine=io_uring hipri=0 fixedbufs=0 registerfiles=1 sqthread_poll=1 verify_pattern=0x22222222%o-16 [uring_rw] rw=randrw ioengine=io_uring hipri=0 fixedbufs=0 registerfiles=0 sqthread_poll=0 verify_pattern=0x33333333%o-16 [uring_sqt_rw] rw=randrw ioengine=io_uring hipri=0 fixedbufs=0 registerfiles=1 sqthread_poll=1 verify_pattern=0x44444444%o-16
