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@ 2006-05-02  7:42 Robert F. Merrill
  2006-05-02  9:59 ` locking bug Jiri Slaby
  0 siblings, 1 reply; 5+ messages in thread
From: Robert F. Merrill @ 2006-05-02  7:42 UTC (permalink / raw)
  To: linux-kernel

------------[ cut here ]------------
kernel BUG at fs/locks.c:1932!
invalid operand: 0000 [#8]
SMP 
Modules linked in: thermal fan button processor ac battery nfs lockd nfs_acl sunrpc ipv6 quota_v1 ide_cd cdrom generic joydev evdev e1000 mousedev piix psmouse i2c_i801 serio_raw pcspkr i2c_core ide_core floppy rtc uhci_hcd ehci_hcd usbcore parport_pc parport shpchp pci_hotplug
CPU:    0
EIP:    0060:[<c015fe6a>]    Not tainted VLI
EFLAGS: 00010246   (2.6.15.7-soda0) 
EIP is at locks_remove_flock+0xbb/0xd7
eax: d87f0cfc   ebx: ca0b0ebc   ecx: 00000000   edx: 00000000
esi: cf340900   edi: ca0b0e18   ebp: c5d75834   esp: cb585efc
ds: 007b   es: 007b   ss: 0068
Process mutt (pid: 2295, threadinfo=cb585000 task=e29f2030)
Stack: 00000000 00000000 00000000 00000000 00000000 cf340900 000008f7 00000000 
       00000000 00000000 cf340900 00000202 00000000 00000000 ffffffff 7fffffff 
       00000000 00000000 00000000 00000000 00000000 00000000 f6cb0b40 00000008 
Call Trace:
 [<c014da9d>] __fput+0x6d/0x125
 [<c014c5ca>] filp_close+0x4e/0x57
 [<c014c63b>] sys_close+0x68/0x7c
 [<c01027b1>] syscall_call+0x7/0xb

^ permalink raw reply	[flat|nested] 5+ messages in thread
* locking bug
@ 2004-12-10 21:34 Ara.T.Howard
  2004-12-10 22:05 ` J. Bruce Fields
  0 siblings, 1 reply; 5+ messages in thread
From: Ara.T.Howard @ 2004-12-10 21:34 UTC (permalink / raw)
  To: nfs


is this a known bug?


~/eg/c here is an NFS mounted dir...


   jib:~/eg/c > uname -a
   Linux jib.ngdc.noaa.gov 2.4.21-20.0.1.ELsmp #1 SMP Wed Nov 24 20:34:01 EST 2004 i686 i686 i386 GNU/Linux

   jib:~/eg/c > ./a.out
   fd <3>
   locking <foobar> => ret <0>
   (sleeping...)



   carp:~/eg/c > uname -a
   Linux carp.ngdc.noaa.gov 2.4.21-20.0.1.ELsmp #1 SMP Wed Nov 24 20:34:01 EST 2004 i686 i686 i386 GNU/Linux

   carp:~/eg/c > ./a.out
   fd <3>
   locking <foobar> => ret <0>
   (sleeping...)



   carp:~/eg/c > cat a.c
   #include <stdlib.h>
   #include <stdio.h>
   #include <sys/types.h>
   #include <sys/stat.h>
   #include <fcntl.h>
   int
   main (argc, argv)
        int argc;
        char **argv;
   {
     struct flock flock;
     char *path;
     int fd, fd2;
     int ret;

     path = argv[1] == NULL ? "foobar" : argv[1];

   /* open file, creating if does not exist, and lock it */
     fd = open (path, O_RDWR);
     if (fd == -1)
       {
         fd = open (path, O_RDWR | O_CREAT);
       }
     printf ("fd <%d>\n", fd);

     flock.l_type = F_WRLCK;
     flock.l_whence = SEEK_SET;
     flock.l_start = 0;
     flock.l_len = 0;

     ret = fcntl (fd, F_SETLK, &flock);
     printf ("locking <%s> => ret <%d>\n", path, ret);

   /* slurp file - this causes the bug */
     fd2 = open (path, O_RDONLY);
     while (read (fd2, &ret, sizeof (int)));
     close (fd2);

   /* getch */
     (void) getc (stdin);
     return (EXIT_SUCCESS);
   }


summary:

   * process on host 0 opens file, locks it, and read it in using separate file
     handle.  it then sleeps holding lock.

   * process on host 1 attempting the exact same sequence (and so expecting to
     find the file locked) is able to obtain the lock.

   * if the file is not slurped this code acts as it's supposed to - process on
     host 1 cannot obtain lock


is this known?  if not should i report here or to redhat?

kind regards.

-a
-- 
===============================================================================
| EMAIL   :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
| PHONE   :: 303.497.6469
| When you do something, you should burn yourself completely, like a good
| bonfire, leaving no trace of yourself.  --Shunryu Suzuki
===============================================================================


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^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2006-05-02  9:58 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-05-02  7:42 Robert F. Merrill
2006-05-02  9:59 ` locking bug Jiri Slaby
  -- strict thread matches above, loose matches on Subject: below --
2004-12-10 21:34 Ara.T.Howard
2004-12-10 22:05 ` J. Bruce Fields
2004-12-10 22:15   ` Ara.T.Howard

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