Re: Q: cat /proc/mdstat blocking?

[Al Viro]

On Fri, Aug 05, 2011 at 02:02:49PM +0200, Ulrich Windl wrote:
> Hi,
> 
> I thought that /proc/mdstat just displays the current state of the MD RAIDs, not querying them, thus never blocking. Unfortunately I could observer a "cat /proc/mdstat" hanging for several seconds when one of the RAID1 legs was unavailable and multipathd was queueing requests to the leg.
> 
> Practically this makes monitoring of the other RAIDs difficult when one bad device is enough to block /proc/mdstat.
> 
> Now my question: Does it work as designed (i.e. as intended), or is this not as intended?

I suspect that something is holding all_mddevs_lock too long; that, or one
of the subdrivers' spinlocks.  Try to find out what it blocks on and what
holds the lock in question...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/