Hi,
Just want to let you know that this patch fixes the 'fault on nofault
entry' panics I had.
It was very easily reproducable with:
---
char *buf; int n=0;
buf=(char *)malloc(1);
for(;;)
buf=(char *)realloc(buf,n++*1024*1024);
---
Ran some tests now and as said it didn't happen again.
Thanks alot.
Mark
On Sun, Jul 28, 2002 at 09:51:57PM +0900, Seigo Tanimura wrote:
> If you are having a trouble of a broken thread state (eg a thread with
> TDS_RUNQ on no run queue) or a mysterious page fault on a kernel
> memory (probably in mi_switch()), you may want to try my patch at:
>
> http://people.FreeBSD.org/~tanimura/patches/procswap.diff.gz
>
> In a nutshell, this patch fixes three bugs:
>
>
> 1. a thread with TDS_RUNQ on no run queue.
>
> This is due to wakeup() and wakeup_one() setting the state to a thread
> to TDS_RUNQ even if the thread has been swapped out. As a thread
> being or having been swapped out cannot be scheduled immediately,
> introduce a new thread state TDS_SWAPPED to note that.
>
>
> 2. a possible race condition for multiple threads to swap in a single
> process.
>
> Since faultin() may block (and likely to do so) without leaving any
> flags for a process being swapped in, more than one threads can call
> faultin() for the same process. Avoid this by adding a new process
> state flag PS_SWAPPINGIN to a process being swapped in.
>
>
> 3. a running thread being swapped out.
>
> Swapout_procs() and swapout() do not check the states of the threads
> in a process about to be swapped out. This causes the pcb and the
> kernel stack of a running thread being unmapped, resulting in a
> page fault in cpu_switch(). Do not swap out a process unless all of
> its threads are either in a run queue or sleeping.
>
> Eventually, it may become our option to swap out only threads that are
> safe to do so.
>
> --
> Seigo Tanimura <[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
>
> To Unsubscribe: send mail to [EMAIL PROTECTED]
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--
Mark Santcroos RIPE Network Coordination Centre
http://www.ripe.net/home/mark/ New Projects Group/TTM
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