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Subject: Re: md_raid: mdX_raid6 looping after sync_action "check" to "idle"
 transition
From:   Donald Buczek <buczek@molgen.mpg.de>
To:     Guoqing Jiang <guoqing.jiang@cloud.ionos.com>,
        Song Liu <song@kernel.org>, linux-raid@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        it+raid@molgen.mpg.de
References: <aa9567fd-38e1-7b9c-b3e1-dc2fdc055da5@molgen.mpg.de>
 <95fbd558-5e46-7a6a-43ac-bcc5ae8581db@cloud.ionos.com>
 <77244d60-1c2d-330e-71e6-4907d4dd65fc@molgen.mpg.de>
 <7c5438c7-2324-cc50-db4d-512587cb0ec9@molgen.mpg.de>
 <b289ae15-ff82-b36e-4be4-a1c8bbdbacd7@cloud.ionos.com>
 <37c158cb-f527-34f5-2482-cae138bc8b07@molgen.mpg.de>
Message-ID: <efb8d47b-ab9b-bdb9-ee2f-fb1be66343b1@molgen.mpg.de>
Date:   Mon, 21 Dec 2020 13:33:58 +0100
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Dear Guoging,

I think now that this is not an issue for md. I've driven a system into that situation again and have clear indication, that this is a problem of the member block device driver.

With md0 in the described errornous state (md0_raid6 busy looping, echo idle > .../sync_action blocked, no progress in mdstat) and md1 operating normally:

     root:deadbird:/scratch/local/# for f in /sys/devices/virtual/block/md?/md/rd*/block/inflight;do echo $f: $(cat $f);done
     /sys/devices/virtual/block/md0/md/rd0/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd1/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd10/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd11/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd12/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd13/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd14/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd15/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd2/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd3/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd4/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd5/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd6/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd7/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd8/block/inflight: 1 0
     /sys/devices/virtual/block/md0/md/rd9/block/inflight: 1 0
     /sys/devices/virtual/block/md1/md/rd0/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd1/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd10/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd11/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd12/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd13/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd14/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd15/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd2/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd3/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd4/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd5/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd6/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd7/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd8/block/inflight: 0 0
     /sys/devices/virtual/block/md1/md/rd9/block/inflight: 0 0

Best
   Donald