Red Hat Bugzilla – Bug 470459
The system stall or panic can occur when /proc/<pid>/oom_score is read
Last modified: 2011-11-29 17:14:08 EST
Description of problem:
In proc_oom_score()@fs/proc/base.c, task_struct is accessed without tasklist_lock. So, there are race condition between reading /proc/<pid>/oom_score and traversing task_list, then system stall or panic can occur. This issue has been fixed on vanilla kernel.
Version-Release number of selected component:
kernel version: 2.6.18-92.el5 (RHEL5.2GA)
Reading from /proc/<pid>/oom_score, it can be reproducible in few minutes, on 16 core SMP box.
Steps to Reproduce:
(1) fork and exit a large amount of processes.
(2) Using /usr/bin/find, read /proc/<pid>/oom_score repeadedly.
The system has stalled.
Neither system stall nor panic occurs.
git patch: "/proc/*/oom_score oops re badness"
Created attachment 322837 [details]
Patch built, tested and posted to rhkernel-list.
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
Updating PM score.
You can download this test kernel from http://people.redhat.com/dzickus/el5
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