Red Hat Bugzilla – Bug 230978
A timing window that causes double freeing file_lock entry
Last modified: 2007-11-16 20:14:55 EST
Description of problem:
Encountered (1) a kernel panic and (2) a system hang on web server running
with mod_jk when ApacheBench tool from another node started.
(1) kernel panic
Panic at line 168 on fs/lock.c displaying "Attempting to free lock on active
lock list" due to a bad fl_link. Please see the the output of crash "log"
command (attached as kernel_panic.txt).
(2) system hang
Loop at line 737 on fs/lock.c with holding lock_kernel due to a self-linked
fl_next. Please see the output of crash "log" command (attached as
Version-Release number of selected component (if applicable):
Steps to Reproduce:
Just run ApacheBench tool for SMP web server.
With some kinds of kernel trapper and by looking at the kernel dump, it is
most likely that the problem was caused by double freeing file_lock entry at a
timing window. Checked LKML, then found http://lkml.org/lkml/2006/5/17/261 and
the patch for this issue has already been applied to upper version.
ApacheBench worked normally with the patch (attached flock.patch), so please
consider applying this patch to the next stability updates or as a security
Created attachment 149252 [details]
crash "log" command output at kernel panic
Please cancel this entry because the same problem has been reported on
ID=230976. I pushed "commit" button twice by mistake.
*** This bug has been marked as a duplicate of 230976 ***