XPost: linux.debian.bugs.dist, linux.kernel 
 From: carnil@debian.org 
  
 Hi Jens, 
  
 Kevin Lumik reported in Debian the following issue (not exactly a 
 minimal reproducer, but bisection results follows): 
  
 On Fri, Sep 26, 2025 at 10:34:22AM +0300, Kevin Lumik wrote: 
  
 > Dear Maintainer, 
 > 
 > After upgrading from Debian Bookworm to Trixie, an issue within KVM guests 
 when creating an LVM snapshot of its volume 
 > has surfaced. When a LVM snapshot is taken from the host, the guest starts 
 to get I/O errors. The issue seems to only 
 > appear when aio=io_uring is specified in the KVM drive parameters and also 
 seems to resolve when downgrading the kernel 
 > package down to 6.1. The issue is also not reproducible when using 
 aio=native. 
 > 
 > KVM args for the drive: "-drive id=drive- 
 > virtio0,format=raw,file=/dev/dom/vps_testsql,cache=none,aio=io 
 uring,index=0,media=disk,if=virtio" 
 > 
 > An IO workload is being created in the VM using "fio --randrepeat=1 
 --ioengine=io_uring --direct=1 --gtod_reduce=1 -- 
 > name=randwrite --filename=/root/test.bin --bs=4k --iodepth=64 --runtime=60 
 --numjobs=32 --readwrite=randwrite --size=1G 
 > --rwmixread=75 --group_reporting" 
 > 
 > After running "lvcreate -s /dev/dom/vps_testsql -n test -L 1G" on the host 
 we can observe fio erroring out: 
 > 
 > ... 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=46977024, buflen=4096 
 > fio: pid=7367, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=261505024, buflen=4096 
 > fio: pid=7374, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=973840384, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=9637888, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=159965184, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=857505792, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=90787840, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=26427392, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=955621376, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=96169984, buflen=4096 
 > fio: pid=7372, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7362, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=203702272, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=814649344, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=91467776, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=948256768, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=105295872, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=75247616, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=1062293504, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=111955968, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=942563328, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=117354496, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=1050402816, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=125419520, buflen=4096 
 > fio: io_u error on file /root/test.bin: Input/output error: write 
 offset=129044480, buflen=4096 
 > fio: pid=7369, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7373, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7348, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7375, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7358, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > fio: pid=7359, err=5/file:io_u.c:1876, func=io_u error, error=Input/output 
 error 
 > 
 > randwrite: (groupid=0, jobs=32): err= 5 (file:io_u.c:1876, func=io_u error, 
 error=Input/output error): pid=7344: Thu Sep 
 > 25 16:28:30 2025 
 >   write: IOPS=194k, BW=758MiB/s (795MB/s)(3976MiB/5244msec); 0 zone resets 
 >    bw (  KiB/s): min=657104, max=1009816, per=100.00%, avg=785345.80, 
 stdev=4331.73, samples=320 
 >    iops        : min=164276, max=252454, avg=196336.40, stdev=1082.93, 
 samples=320 
 >   cpu          : usr=0.33%, sys=1.07%, ctx=18912, majf=0, minf=455 
 >   IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=99. 
 8% 
 >      submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, 
 >=64=0.0% 
 >      complete  : 0=0.1%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, 
 >=64=0.0% 
 >      issued rwts: total=0,1019955,0,0 short=0,0,0,0 dropped=0,0,0,0 
 >      latency   : target=0, window=0, percentile=100.00%, depth=64 
 > 
 > Run status group 0 (all jobs): 
 >   WRITE: bw=758MiB/s (795MB/s), 758MiB/s-758MiB/s (795MB/s-795MB/s), 
 io=3976MiB (4169MB), run=5244-5244msec 
 > 
 > Disk stats (read/write): 
 >   vda: ios=1/1001361, merge=0/2, ticks=0/10314531, in_queue=10314549, 
 util=97.82% 
 > Bus error 
 > 
 > --- 
 > 
 > And the error is also visible in the kernel error log of the VM: 
 > [  361.962970] I/O error, dev vda, sector 83277192 op 0x1:(WRITE) flags 
 0x8800 phys_seg 1 prio class 2 
  
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