Red Hat Bugzilla – Bug 230976
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 149251 [details]
crash "log" command output at kernel panic
Created attachment 149253 [details]
crash "log" command output at system hang
Created attachment 149254 [details]
*** Bug 230978 has been marked as a duplicate of this bug. ***
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
*** This bug has been marked as a duplicate of 234367 ***