Re: XFS Lock debugging noise or real problem?

From: Linda Walsh
Date: Wed Aug 13 2008 - 21:04:41 EST


Dave Chinner wrote:
I've asked the lockdep ppl to treat stuff like memory reclaim and
the iprune_mutex specially because of this recursive calling nature
of memory reclaim, but so far nothing has happened....
---
So it's really a kernel bug, not an XFS bug...(?)


FWIW, I think that recent changes have resulted in the xfs_fsr case
(swap_extents) being annotated properly so that one should go
away.
---
If it was limited to xfs_fsr, that'd be tolerable -- but its
cropping up in random user-level-apps (imaps, sort, et al).



Well, any debugging code is really designed for test and dev systems,
not for production systems.....
---
The lock-correctness code is described as a feature to provide
"provability". It's not called "debugging" and I don't regard that as
"debugging" -- but something that any production system that wants
operational integrity over a minor 'speed hit', would "theoretically"
want.

If it is "debug" code, it should be labeled as such -- but
code that can mathematically guarantee that parts of the kernel operate
correctly seems like a _reliability_ feature, not a debugging feature.

Thanks for the insight -- very appreciated.

linda


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