On 12/7/10 3:41 AM, Attilio Rao wrote:
2010/12/7 Erik Cederstrand<e...@cederstrand.dk>:
Den 07/12/2010 kl. 10.20 skrev Garrett Cooper:

On Dec 7, 2010, at 12:26 AM, Mehmet Erol Sanliturk<m.e.sanlit...@gmail.com>  
wrote:

A Dmesg.TXT is attached having a lock order reversal .
    The mount LOR is well known.
I see that this is the standard response to lot's of LOR reports. It seems to 
be one of the most-reported errors on CURRENT (and it's certainly a loud one), 
but I think a lot of people waste time researching the error and browsing 
Bjoerns LOR page, only to get the above response (not picking on you, Garrett).

Do we have the possibility of silencing well-known and presumably harmless 
LOR's if there isn't sufficient motivation to fix the source?
Witness has an 'internal blessing list' we never wanted to use in
order to keep them popping up as reminder.
Actually, the fact the LOR is 'known' doesn't mean it is 'analyzed'.
The very few 'Analyzed but harmless' cases in the past have been
handled via _NOWITNESS flags I guess.

the problem is that the witness output tells you the second case (the reversed case) but it doesn't have any clues about the first case (the one that wsa the other way around).

An extended witness might use a lot of memory but associate with each lock a 'last place called when a lock was already held' that might give a clue as to where the other instance was. I'm not volunteering to write it, but it might be very worth while.. I'd certainly like to hear other ideas as well.


Attilio



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