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    SubjectRe: namespaces?: bug at mm/slub.c:2750
    From
    On Wed, Feb 11, 2009 at 9:07 AM, Andrew Morton
    <akpm@linux-foundation.org> wrote:
    >> In case you missed it, KOSAKI Motohiro posted a similar stack-trace
    >> (but not the same BUG) in this thread:
    >> http://lkml.org/lkml/2009/2/10/7
    >>
    >
    > Both traces include the newly-added put_cred_rcu(). Suspicious.
    >

    I have this test case which triggers it regularly after some minutes:

    #include <sys/wait.h>
    #include <sys/types.h>

    #include <errno.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>

    int main(int argc, char* argv[])
    {
    unsigned int i;

    if (fork() == 0) {
    while (1)
    system("echo -n .");
    }

    for (i = 0; i < 2; ++i) {
    if (fork() == 0) {
    while (1) {
    setreuid(0, 0xcafeba);
    setreuid(0xcafeba, 0);

    setreuid(0, 0xcafebb);
    setreuid(0xcafebb, 0);
    }

    exit(EXIT_SUCCESS);
    }
    }

    while (!(wait(NULL) == -1 && errno == ECHILD))
    ;

    return 0;
    }

    It seems to be the combination of exec() and setreuid(), but I
    couldn't get it to work with just exec() instead of system(). It is
    possible that CONFIG_USER_SCHED must be =y for this to work. It can
    probably be simplified too...


    Vegard

    --
    "The animistic metaphor of the bug that maliciously sneaked in while
    the programmer was not looking is intellectually dishonest as it
    disguises that the error is the programmer's own creation."
    -- E. W. Dijkstra, EWD1036


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