Re: [2.6.2] Badness in futex_wait revisited

From: Dirk Morris (dmorris_at_metavize.com)
Date: 03/31/04

  • Next message: Jesse Barnes: "Re: 2.6.5-rc1-mm2" 
    Date:	Wed, 31 Mar 2004 10:59:46 -0800
To: Jamie Lokier <jamie@shareable.org>

    Jamie Lokier wrote:

    >If you have a small test program (or pair of programs) that
    >consistently triggers this message on any machine running 2.6.4, that
    >would be very helpful indeed.
    >
    >
    Here ya go. :)

    * $Id: foo.c,v 1.00 2004/03/31 10:51:19 dmorris Exp $ */
    /* gcc foo.c -o foo -pthread */
    #include <stdlib.h>
    #include <stdio.h>
    #include <unistd.h>
    #include <pthread.h>
    #include <semaphore.h>

    sem_t sem;

    void* make_system_call (void* arg)
    {
        while(1) {
            sleep(1);
            system("/bin/true");
        }
        return NULL;
    }

    int main(void)
    {
        pthread_t id;
        sem_init(&sem,0,0);
        pthread_create(&id,NULL,make_system_call,NULL);
        while (sem_wait(&sem)<0)
            perror("sem_wait");
        return 0;
    }

    Output for me is :
    ~ # uname
    -a
    [dmorris @ gobbles]
    Linux gobbles 2.6.4 #2 SMP Mon Mar 29 17:15:08 PST 2004 i686 GNU/Linux
    ~ #
    ./foo
    [dmorris @ gobbles]
    sem_wait: Interrupted system call
    sem_wait: Interrupted system call
    sem_wait: Interrupted system call
    sem_wait: Interrupted system call
    ...

    meanwhile kern.log spits out:
    Mar 30 16:40:23 gobbles kernel: Badness in futex_wait at kernel/futex.c:508
    Mar 30 16:40:23 gobbles kernel: Call Trace:
    Mar 30 16:40:23 gobbles kernel: [<c0139a28>] futex_wait+0x1a8/0x1c0
    Mar 30 16:40:23 gobbles kernel: [<c011efc0>] default_wake_function+0x0/0x20
    Mar 30 16:40:23 gobbles kernel: [<c011efc0>] default_wake_function+0x0/0x20
    Mar 30 16:40:23 gobbles kernel: [<c012d020>] do_timer+0xc0/0xd0
    Mar 30 16:40:23 gobbles kernel: [<c0139d30>] do_futex+0x70/0x80
    Mar 30 16:40:23 gobbles kernel: [<c0139e64>] sys_futex+0x124/0x140
    Mar 30 16:40:23 gobbles kernel: [<c015ef11>] sys_write+0x61/0x70
    Mar 30 16:40:23 gobbles kernel: [<c01095db>] syscall_call+0x7/0xb
    Mar 30 16:40:23 gobbles kernel:

    I can do this on multiple machines, so I won't include all the box info.
    If you need it let me know.

    Thanks! :)
    -Dirk

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