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From: Neil Brown <>
To: "Dan Williams" <>
Cc: "Jens Axboe" <>,,,,,
Subject: Re: AMD64 oops in CFQ code
Date: Fri, 23 Mar 2007 11:44:58 +1100	[thread overview]
Message-ID: <17923.8970.917375.917772@notabene.brown> (raw)
In-Reply-To: message from Dan Williams on Thursday March 22

On Thursday March 22, wrote:
> Not a cfq failure, but I have been able to reproduce a different oops
> at array stop time while i/o's were pending.  I have not dug into it
> enough to suggest a patch, but I wonder if it is somehow related to
> the cfq failure since it involves congestion and drives going away:

Thanks.   I know about that one and have a patch about to be posted
which should fix it.  But I don't completely understand it.

When a raid5 array shuts down, it clears mddev->private, but doesn't
clean q->backing_dev_info.congested_fn.  So if someone tries to call
that congested_fn, it will try to dereference mddev->private and Oops.

Only by the time that raid5 is shutting down, no-one should have a
reference to the device any more, and no-one should be in a position
to call congested_fn !!

Maybe pdflush is just trying to sync the block device, even though
there is no dirty date .... dunno....

But I don't think it is related to the cfq problem as this one is only
a problem when the array is being stopped.


  parent reply	other threads:[~2007-03-23  0:45 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-22 12:38 linux
2007-03-22 18:41 ` Jens Axboe
2007-03-22 18:54   ` linux
2007-03-22 19:00     ` Jens Axboe
2007-03-22 23:59       ` Neil Brown
2007-03-23  0:31         ` Dan Williams
2007-03-23  0:33           ` Dan Williams
2007-03-23  0:44           ` Neil Brown [this message]
2007-03-23 17:46             ` linux
2007-04-03  5:49               ` Tejun Heo
2007-04-03 13:03                 ` linux
2007-04-03 13:11                   ` Tejun Heo
2007-04-04 23:22                 ` Bill Davidsen
2007-04-05  4:13                   ` Lee Revell
2007-04-05  4:29                     ` Tejun Heo
2007-03-22 18:43 ` Aristeu Sergio Rozanski Filho

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