seg fault on kse_release () (fwd)

[Yan Yu]

Hi, thanks a LOT for looking into this.
yes, that is exactly my output before the SEG fault happens (btw, i add
"if (p)" before
"p[id]++ ", the prob remains..
what confuses me is that, if the system is out of memory, then i should
see the error returned from pthread_create() or calloc(), but not SEG
fault, or i must have missed something?

Thanks,
yan


On Tue, 25 Jan 2005, Jose Hidalgo Herrera wrote:

> I ran it into:
> 4.11-STABLE FreeBSD Wed Jan 19 15:23:33 CST 2005
> What you find in
> http://www1.cr.freebsd.org/~jose/stress.tgz
> is the output of:
> ktrace ./a.out > stress.txt
>
>
> On Mon, 2005-01-24 at 14:27 -0800, Yan Yu wrote:
> > Hi, all,  I have a newbie Q:
> >     I am trying to use creating large number of threads and allocting
> > memory to stress the system.
> > My user program causes SEG fault in the kernel code, kse_release () in
> > kern_kse.c.
> > (it SEG fault before the system can be stressed;(
> >
> > the stack when the SEG fault happens are:
> > #0  0x08064e54 in kse_release ()
> > #1  0x080531c4 in kse_sched_single ()
> > #2  0x00000000 in ?? ()
> >
> > My simple program is:
> > I have a simple function to create threads:
> >
> > #define NUM_THREADS     5000
> > #define THREADS_IN_ONE_PROCESS  5
> > #define BSIZE  500000
> > static int  cc;
> >
> > void CreateThread(int n)
> > {
> >    assert( n <= NUM_THREADS );
> >    pthread_t threads[NUM_THREADS];
> >    int rc, t;
> >    for(t=0;t < n;t++){
> >       printf("#%d: Creating thread %d\n", cc, t);
> >       cc++;
> >       rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
> >       if (rc){
> >          printf("ERROR; return code from pthread_create() is %d\n", rc);
> >       }
> >    }
> >
> >    unsigned long id;
> >    char * p = (char *) calloc(BSIZE, sizeof(char) );
> >    if ( p == NULL )
> >    {
> >         fprintf(stderr, "calloc error\n");
> >    }
> >    while (1)
> >    {
> >         while (BSIZE <= (id = rand() / (RAND_MAX/BSIZE)));
> >         p[id] ++;
> >    }
> > }
> >
> > void *PrintHello(void *threadid)
> > {
> >    printf("\n%d: Hello World!\n", threadid);
> >    CreateThread(THREADS_IN_ONE_PROCESS);
> >    pthread_exit(NULL);
> > }
> >
> > int main (int argc, char *argv[])
> > {
> >    CreateThread(THREADS_IN_ONE_PROCESS);
> > }
> >
> > The SEG fault happens after creating nearly 5000 threads.
> > and I use the default pthread.h coming w/ freeBSD 5.3
> > #define PTHREAD_KEYS_MAX                        256
> > #define PTHREAD_STACK_MIN                       (1 << 22)
> > #define PTHREAD_THREADS_MAX                     ULONG_MAX
> >
> >
> > Any idea on what might happen?
> >
> > Many Thanks!
> > yan
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