On Thu, 25 Sep 2014 18:12:07 +0200 Francis Moreau <francis.moro@xxxxxxxxx>
wrote:
> Hello,
>
> On 06/25/2014 03:03 AM, NeilBrown wrote:
> > On Tue, 24 Jun 2014 17:38:30 +0200 Francis Moreau <francis.moro@xxxxxxxxx>
> > wrote:
> >
> >> Hello,
> >>
> >> I'm having the folloing behaviour with kernel 3.14.5 and mdadm v3.3.1.
> >>
> >> After stopping all arrays, I still can see one of them in /sys/block/:
> >>
> >> # cat /proc/mdstat
> >> Personalities : [raid1]
> >> md125 : active raid1 sdb3[1] sda3[0]
> >> 483688448 blocks super 1.2 [2/2] [UU]
> >> [======>..............] resync = 34.9% (169161280/483688448)
> >> finish=44.0min speed=118852K/sec
> >> bitmap: 3/4 pages [12KB], 65536KB chunk
> >>
> >> md126 : active raid1 sdb2[1] sda2[0]
> >> 4038656 blocks super 1.2 [2/2] [UU]
> >>
> >> md127 : active raid1 sdb1[1] sda1[0]
> >> 524224 blocks super 1.0 [2/2] [UU]
> >>
> >> unused devices: <none>
> >>
> >> # mdadm --stop /dev/md12[567]
> >> mdadm: stopped /dev/md125
> >> mdadm: stopped /dev/md126
> >> mdadm: stopped /dev/md127
> >>
> >> # cat /proc/mdstat
> >> Personalities : [raid1]
> >> unused devices: <none>
> >>
> >> # ls /sys/block/
> >> md126 sda sdb sdc sr0
> >>
> >> # ls /sys/block/md126/md/
> >> array_size array_state bitmap chunk_size component_size layout
> >> level max_read_errors metadata_version new_dev raid_disks
> >> reshape_direction reshape_position resync_start safe_mode_delay
> >>
> >> # dmesg
> >> ....
> >> [ 1573.715476] md125: detected capacity change from 495296970752 to 0
> >> [ 1573.715626] md: md125 stopped.
> >> [ 1573.715633] md: unbind<sdb3>
> >> [ 1573.740681] md: export_rdev(sdb3)
> >> [ 1573.740694] md: unbind<sda3>
> >> [ 1573.754008] md: export_rdev(sda3)
> >> [ 1573.773398] md126: detected capacity change from 4135583744 to 0
> >> [ 1573.773403] md: md126 stopped.
> >> [ 1573.773410] md: unbind<sdb2>
> >> [ 1573.820652] md: export_rdev(sdb2)
> >> [ 1573.820664] md: unbind<sda2>
> >> [ 1573.873974] md: export_rdev(sda2)
> >> [ 1573.889904] md127: detected capacity change from 536805376 to 0
> >> [ 1573.889910] md: md127 stopped.
> >> [ 1573.889917] md: unbind<sdb1>
> >> [ 1573.913978] md: export_rdev(sdb1)
> >> [ 1573.914033] md: unbind<sda1>
> >> [ 1573.940627] md: export_rdev(sda1)
> >>
> >> After waiting a couple of min, stopping again md126 worked:
> >>
> >> [ 1835.755661] md: md126 stopped.
> >>
> >> Is this expected ?
> >
> > No overly surprising.
> >
> > This is probably caused by udev, or something udev runs, opening /dev/md126
> > after it has been stopped. This has the effect of creating an empty inactive
> > array.
> > e.g.
> >
>
> Sorry for resurecting this again, but I'm still seeing this.
>
> Sebastian saw the same behaviour with udev 215 and it appeared that this
> specific version introduced a regression which resulted in the same
> behavior I described initialy.
>
> But in my case, the version of udev used is older (204).
>
> I tried to find out what could have opened the md device by using fuser,
> but fuser reports no users.
It is probably a transient open/close.
>
> I took a look to the udev rules which are the one shipped by mdadm 3.3.2
> but nothing keep the device opened during the remove event.
>
> Could you give me some hints here to debug this ?
Modify md_open in drivers/md/md.c to add
printk("Opened by %s\n", current->comm);
and build a new kernel. That will tell you the name of the process which
opened the device.
NeilBrown
>
> Thanks
>
>
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