[Bug 21559] "scheduling while atomic" with brctl and NFS-mounted root

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Wed Dec 28 16:13:50 UTC 2005

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------- Additional Comments From gjc at inescporto.pt  2005-12-28 16:13 UTC -------
(In reply to comment #10)
> Of course it is a NFS problem, the error occurs when the interface brings itself
> down for bridging and then does an mdelay, which allows NFS to be scheduled and
> then it tries to schedule some work, and in doing so, causes this bug.

  OK.  What I meant is that it's not a NFS-when-used-as-root-filesystem problem.

> IMO, this problem is related to rhine and NFS in general. The call down for the
> rhine driver to perform the action that bridging needs does the mdelay() (which
> not all ethernet drivers will do). The briding code says that it handles this
> before performing this call (scheduling), but the problem is that rhine does a
> spinlock during this call, so it cannot handle the scheduling (spinlocks are
> atomic). I'm inclined to think the rhine driver is at fault here.

  I'm no kernel hacker, so no comment :P

> Question, are you using NFSv4 or NFSv3? The code paths are quite different
> between the two during the nfs_do_access().

  'mount' reports: on / type nfs

So I imagine that v3 means NFS version 3...

PS: today I got lucky once and managed to run my bridge script without the
kernel locking (in spite of the usual traces in dmesg); but I rebooted the
machine and tried again and it locked up this time.  So it's a problem that
happens most of the times, but not always.

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