Re: [9fans] page fault with lock held

[jmk@plan9.bell-labs.com]

no, you should not be holding a spinlock when trying that.
why is your driver trying to copy directly to user space,
isn't it a subdevice of devsd? (i'm not saying that's the way
to do it, just curious).

On Tue Apr 12 13:20:53 EDT 2005, sah@softcardsystems.com wrote:
> Hello 9fans,
> 
> I'm testing my AoE driver and have hit something curious.
> 
> On devaoe.c read, after getting the sectors from the
> remote disk and when trying to copy the data to the
> user process using memmove, I get a write page fault.
> At the time, I happen to be holding a spinlock over
> the device structure, which causes both
> port/fault.c:/^fault/ and port/fault.c/^seg/ (via qlock)
> to squawk at me about up->nlocks.ref > 0.
> 
> The user address in question is 7fffaedc.  Firstly, does
> this address seem appropriate and secondly, is dropping
> the spinlock during the memmove appropriate?
> 
> All signs point to yes, but I'd like some reassurance.
> 
> Cheers,
> 
> Sam