Hi I am testing fio with bs ranges 1k-10k 2k-10k 3k-10k 4k-10k 5k-10k 6k-10k. The test works fine for the below run: fio --name=App2 --size=10m --rw=read --blocksize_range=1k-10k # fio --name=App2 --size=10m --rw=read --blocksize_range=2k-10k # fio --name=App2 --size=10m --rw=read --blocksize_range=5k-10k But error throws on below runs # fio --name=App2 --size=10m --rw=read --blocksize_range=3k-10k # fio --name=App2 --size=10m --rw=read --blocksize_range=4k-10k # fio --name=App2 --size=10m --rw=read --blocksize_range=6k-10k App2: (g=0): rw=read, bs=(R) 3072B-10.0KiB, (W) 3072B-10.0KiB, (T) 3072B-10.0KiB, ioengine=psync, iodepth=1 fio-3.12-17-g0fcbc0 Starting 1 process *** Error in `fio': double free or corruption (!prev): 0x0000555f92a80a60 *** fio: pid=1468, got signal=6 App2: (groupid=0, jobs=1): err= 0: pid=1468: Wed Dec 12 19:09:07 2018 read: IOPS=8365, BW=52.9MiB/s (55.5MB/s)(9.00MiB/189msec) clat (nsec): min=874, max=74912k, avg=116222.51, stdev=2186743.16 lat (nsec): min=912, max=74912k, avg=116373.83, stdev=2186743.70 clat percentiles (nsec): | 1.00th=[ 964], 5.00th=[ 1128], 10.00th=[ 1368], | 20.00th=[ 1672], 30.00th=[ 2008], 40.00th=[ 2288], | 50.00th=[ 2704], 60.00th=[ 3088], 70.00th=[ 3536], | 80.00th=[ 4768], 90.00th=[ 6304], 95.00th=[ 8160], | 99.00th=[ 544768], 99.50th=[ 2113536], 99.90th=[30539776], | 99.95th=[74973184], 99.99th=[74973184] lat (nsec) : 1000=1.52% lat (usec) : 2=28.34%, 4=44.85%, 10=21.70%, 20=0.51%, 50=0.32% lat (usec) : 250=0.25%, 500=1.20%, 750=0.76% lat (msec) : 4=0.25%, 20=0.13%, 50=0.13%, 100=0.06% cpu : usr=3.72%, sys=3.72%, ctx=43, majf=0, minf=14 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued rwts: total=1581,0,0,0 short=0,0,0,0 dropped=0,0,0,0 latency : target=0, window=0, percentile=100.00%, depth=1 Run status group 0 (all jobs): READ: bw=52.9MiB/s (55.5MB/s), 52.9MiB/s-52.9MiB/s (55.5MB/s-55.5MB/s), io=9.00MiB (10.5MB), run=189-189msec Disk stats (read/write): sda: ios=24/0, merge=0/0, ticks=188/0, in_queue=260, util=55.70% I believe the expected test has run properly but why the error has thrown for the particular ranges. Thanks and Regards, Mohan