Public bug reported:
This is an easily reproducible bug occurring in our cloud environment.
The issue is that /proc/diskstats has all 0s for md0, a raid0 array.
/sys/block/md0/stat also has all 0s.
$ uname -r
5.13.0-1022-aws
$ cat /proc/diskstats
7 0 loop0 344 0 20160 43 0 0 0 0 0 880 43 0 0 0 0 0 0
7 1 loop1 49 0 974 12 0 0 0 0 0 20 12 0 0 0 0 0 0
7 2 loop2 253 0 4720 47 0 0 0 0 0 228 47 0 0 0 0 0 0
7 3 loop3 6733 0 462030 271 0 0 0 0 0 19352 271 0 0 0 0 0 0
7 4 loop4 69 0 2456 26 0 0 0 0 0 36 26 0 0 0 0 0 0
7 5 loop5 42 0 944 11 0 0 0 0 0 16 11 0 0 0 0 0 0
7 6 loop6 11 0 28 0 0 0 0 0 0 4 0 0 0 0 0 0 0
7 7 loop7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
259 0 nvme0n1 12418 7104 947061 6454 94697 12570 1054464 78054 0 33540
84508 0 0 0 0 0 0
259 1 nvme0n1p1 12117 7104 936053 6381 94697 12570 1054464 78054 0 33472
84435 0 0 0 0 0 0
259 2 nvme1n1 8105 21 79736 4085 24991 30424 443720 1150 0 39332 5236 0
0 0 0 0 0
259 3 nvme2n1 1044 0 22470 191 16968 29804 374432 702 0 29344 893 0 0 0
0 0 0
9 0 md0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
$ cat /sys/block/md0/stat
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
We see this on all similarly configured instances with this kernel. With
a slightly older kernel, the problem does not happen (using the same
instance type):
$ uname -r
5.11.0-1028-aws
$ cat /proc/diskstats
7 0 loop0 385 0 23980 62 0 0 0 0 0 1072 62 0 0 0 0 0 0
7 1 loop1 57 0 2768 14 0 0 0 0 0 64 14 0 0 0 0 0 0
7 2 loop2 1274 0 80288 67 0 0 0 0 0 3308 67 0 0 0 0 0 0
7 3 loop3 125 0 4756 22 0 0 0 0 0 84 22 0 0 0 0 0 0
7 4 loop4 6928 0 485026 299 0 0 0 0 0 19676 299 0 0 0 0 0 0
7 5 loop5 1403 0 96676 84 0 0 0 0 0 4224 84 0 0 0 0 0 0
7 6 loop6 423 0 26558 60 0 0 0 0 0 1132 60 0 0 0 0 0 0
7 7 loop7 920 0 50490 43 0 0 0 0 0 2100 43 0 0 0 0 0 0
259 0 nvme0n1 263525 48497 11700905 168289 7397504 1092004 83304504
6618617 0 2318176 6786907 0 0 0 0 0 0
259 1 nvme0n1p1 261591 48497 11636377 167726 7397504 1092004 83304504
6618617 0 2318004 6786343 0 0 0 0 0 0
259 2 nvme2n1 210691 47 34312138 145597 4361154622 39741208 889622866304
947127588 0 405758020 951731842 51375 0 129566145192 4458656 0 0
259 3 nvme1n1 220561 171 34057770 148965 4363589540 40496575
889678501709 963085301 0 409181904 967699619 47256 0 129564097320 4465352 0 0
9 0 md0 375711 0 68340222 258768 7141406762 0 1779301368005 2040115436
0 421027688 2045172840 66637 0 259130242512 4798636 0 0
7 8 loop8 76 0 3766 1 0 0 0 0 0 44 1 0 0 0 0 0 0
7 9 loop9 66 0 2036 1 0 0 0 0 0 40 1 0 0 0 0 0 0
7 10 loop10 78 0 3022 1 0 0 0 0 0 32 1 0 0 0 0 0 0
7 11 loop11 23 0 64 0 0 0 0 0 0 8 0 0 0 0 0 0 0
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.13.0-1022-aws 5.13.0-1022.24~20.04.1
ProcVersionSignature: User Name 5.13.0-1022.24~20.04.1-aws 5.13.19
Uname: Linux 5.13.0-1022-aws x86_64
ApportVersion: 2.20.11-0ubuntu27.23
Architecture: amd64
CasperMD5CheckResult: skip
Date: Fri Apr 22 20:07:26 2022
Ec2AMI: ami-04cf18ef54851b02b
Ec2AMIManifest: (unknown)
Ec2AvailabilityZone: us-east-1d
Ec2InstanceType: i3en.6xlarge
Ec2Kernel: unavailable
Ec2Ramdisk: unavailable
ProcEnviron:
TERM=screen-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=C.UTF-8
SHELL=/bin/bash
SourcePackage: linux-signed-aws-5.13
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: linux-signed-aws-5.13 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug ec2-images focal
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https://bugs.launchpad.net/bugs/1969991
Title:
/proc/diskstats contains all 0s for a raid array
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