On 24-May-01 Michael Harnois wrote:
> On Wed, 23 May 2001 22:10:09 -0300 (ADT), The Hermit Hacker <[EMAIL PROTECTED]>
> said:
>     > Oops ... neat, now it just locked up solid and ctl-alt-esc
>     > doesn't even get me to debugger :(
> This has been my experience for about a week on the -current kernel
> ... I held out high hopes that these changes by John and Alfred over
> the past 24 hours or so would fix it, but no go ...

I had a epiphany this morning, and will be committing a bandaid to get current
workign again on SMP systems.  The problem occurs when we take a fault while
hold the vm lock already.  In that case, the VM was in an inconsistent state
when we faulted.  That's why we were holding the lock when we faulted.  Well,
there are places in the fault handler where we release the vm lock to sleep or
acquire Giant or some such.  When we do so, we allow another thread to try and
dink with the VM, which can lead to threads trying to use free'd pages, etc. on
SMP systems.  The bandaid is to stick all the VM related syscalls that were
marked MPSAFE back under Giant for the time being, which I will do shortly.


John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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