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Re: TAKE 981498 - Use KM_NOFS for debug trace buffers

To: Bhagi rathi <jahnu77@xxxxxxxxx>
Subject: Re: TAKE 981498 - Use KM_NOFS for debug trace buffers
From: Eric Sandeen <sandeen@xxxxxxxxxxx>
Date: Wed, 06 Aug 2008 14:56:17 -0500
Cc: Lachlan McIlroy <lachlan@xxxxxxx>, sgi.bugs.xfs@xxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <cc7060690808061012x43511581m15c794e72129becc@xxxxxxxxxxxxxx>
References: <20080806061553.A8D8958C52A4@xxxxxxxxxxxxxxxxxxxxxxx> <cc7060690808061012x43511581m15c794e72129becc@xxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
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Bhagi rathi wrote:
> I couldn't get a chance to read the diff's completely. If I click on
> Lachlan's url for diff's, I couldn't access them. 

Try again, it takes a while for cvs to catch up.

-Eric

> It looks to me that
> the issue is not just with trace buffers. It can extend to xfs_iformat
> as well. The same dead-lock can spring via
> 
> xfs_iread -> xfs_iformat -> xfs_iformat_extents -> xfs_iext_add ->
> xfs_iext_inline_to_direct -> which can do kmem_alloc with
> KM_SLEEP flag.
> 
> 
> The source of the problem is that holding a lock and entering into
> file-system once again. This can lead to dead-lock on the same
> clustered buffer during cleaning of log space.
> 
> Cheers,
> Bhagi.


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