Messages in this thread | | | From | Dawson Engler <> | Subject | Re: [CHECKER] potential deadlocks | Date | Mon, 3 Mar 2003 23:52:24 -0800 (PST) |
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> Andrew Morton writes: > > Dawson Engler <engler@csl.stanford.edu> wrote: > > > > > > BTW, are there known deadlocks (harmless or otherwise)? Debugging > > > the checker is a bit hard since false negatives are silent... > > > > Known deadlocks tend to get fixed. But I am surprised that you did not > > encounter more of them. > > > > btw, the filesystem transaction operations can be treated as sleeping locks. > > So for ext3, journal_start()/journal_stop() may, for lock-ranking purposes, > > be treated in the same way as taking and releasing a per-superblock > > semaphore. Other filesystems probably have similar restrictions. > > > > So are page-fault and memory allocation events, because thread > blocks on them, and deadlocks involving servicing page fault or memory > laundering have definitely been seen.
Do you mean calls to copy_*_user and kmalloc(GFP_WAIT) or did you have something else in mind as well?
> We have (incomplete) description of kernel lock ordering, which is > centered around reiser4 locks, but also includes some core kernel stuff. > > It is available at > > http://www.namesys.com/v4/lock-ordering.dot --- source for Bell-Labs' dot(1) > http://www.namesys.com/v4/lock-ordering.ps --- postscript output, produced from the .dot source
Wonderful; thanks!
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