Messages in this thread | | | Date | Wed, 08 Sep 2004 13:08:13 +1000 | From | Nick Piggin <> | Subject | Re: [CHECKER] potential NFS deadlock in 2.6.8.1 |
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Dawson Engler wrote: > Hi All, > > below is a possible deadlock in the linux-2.6.8.1 NFS found by a static > deadlock checker I'm writing. Let me know if it looks valid and/or > whether the output is too cryptic. > > Thanks, > Dawson > > ------------------------------------------------------------------ > > ERROR:DEADLOCK: 2 thread cycle: > lock_kernel <<===>> client_sema >
Hi Dawson, your tool looks nice. I don't think the output is too cryptic.
However, I think these deadlocks may be incorrect because lock_kernel is not a normal lock. It gets dropped when the thread blocks, so I *think* it is basically invisible to any sort of blocking lock when it comes to deadlock cycles.
So if your threads interleave like this: 1 2 lock_kernel(); down(semaphore); lock_kernel(); down(semaphore);
Then thread 2 will spin on the lock_kernel lock (bkl) until thread 1 hits down(semaphore) and goes to sleep, releasing the bkl. Thread 2 takes the bkl and proceeds.
I think? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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