Hi,
I'm trying to do some debugging with 2.6.0 + mm1 patch (I attach my .config) and I found out this very strange thing when changing fs/open.c (about the line 933):

ORIGINAL CODE:
...
asmlinkage long sys_open(const char __user * filename, int flags, int mode)
{
        char * tmp;
        int fd, error;

#if BITS_PER_LONG != 32
        flags |= O_LARGEFILE;
#endif
        tmp = getname(filename);
        fd = PTR_ERR(tmp);
...


MY TINY MODIFICATION:
...
asmlinkage long sys_open(const char __user * filename, int flags, int mode)
{
        char * tmp;
        int fd, error;
	char tmp_path[PATH_MAX],tmp2_path[PATH_MAX];


#if BITS_PER_LONG != 32
        flags |= O_LARGEFILE;
#endif
        tmp = getname(filename);
	printk (KERN_INFO "sys_open: %s\n",tmp);
        fd = PTR_ERR(tmp);
...


This causes kernel to panic during boot. Messages are: (maybe some typos - writing from paper)
...
NET: Registering protocol family 17
Unable to handle kernel paging request at virtual address fffffff2
... (some registry/stack debug output)
Kernel panic: attempted to kill the idle task!
Bad: scheduling while atomic!


When I do this add only "char tmp_path[PATH_MAX], tmp2_path[PATH_MAX]" (no printk), it panics out:
...
NET: Registering protocol family 17
Unable to handle kernel paging request at virtual address 7970709. (can't read last char - if necessary I can retest it)
... (some registry/stack debug output)
Kernel panic: attempted to kill init!


Disabling preemptive scheduler has no effect (I suspected it because "...Bad: scheduling while atomic!").


VERY STRANGE - when I try this modyfication:
...
asmlinkage long sys_open(const char __user * filename, int flags, int mode)
{
        char * tmp;
        int fd, error;
	char tmp_path[PATH_MAX];  // (OR WITHOUT THIS LINE AT ALL!)


#if BITS_PER_LONG != 32
        flags |= O_LARGEFILE;
#endif
        tmp = getname(filename);
	printk (KERN_INFO "sys_open: %s\n",tmp);
        fd = PTR_ERR(tmp);
...


THIS WORKS BUT (!!!) there are some Oops (or whatever) AFTER kernel booted up (something with ACPI & registery/stack output) and about time starting up syslogd (I couldn't find it nowhere in /var/log/messsages :-((()


And BTW - I'm running Fedora Core 1.





-- 
Libor Vanek