Bug 456686 - race in aio_complete() leads to process hang
race in aio_complete() leads to process hang
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
All Linux
urgent Severity medium
: rc
: ---
Assigned To: Jeff Moyer
Martin Jenner
: ZStream
Depends On:
Blocks: 461304 475814 489935
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Reported: 2008-07-25 11:33 EDT by Bryn M. Reeves
Modified: 2009-05-22 06:44 EDT (History)
5 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2009-05-18 15:08:21 EDT
Type: ---
Regression: ---
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Documentation: ---
Verified Versions:
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Bryn M. Reeves 2008-07-25 11:33:37 EDT
Description of problem:
There is a missing memory barrier in the current aio_complete in the RHEL4
kernels causing a race between read_events/aio_complete causing the thread in
read_events to sleep indefinitely, hanging the application that is waiting on
I/O completion.

This was reported upstream by Quentin Barnes of Yahoo:


Fix has been merged in 2.6.26:


And was also accepted for 2.6.24.y:


Version-Release number of selected component (if applicable):

How reproducible:
Unclear. Depends on the AIO application; Quentin reports seeing hangs virtually
100% of the time. Looking for a straightforward reproducer for this now and will
update with details when they are available.

Steps to Reproduce:
< to be filled >
Actual results:
Application hangs in read_events

Expected results:
No hang. AIO completes as normal.

Additional info:
Comment 1 RHEL Product and Program Management 2008-09-03 09:12:05 EDT
Updating PM score.
Comment 2 RHEL Product and Program Management 2008-09-22 13:53:39 EDT
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
Comment 3 Jeff Moyer 2009-01-05 14:50:24 EST
Patch posted for review:
Comment 4 Vivek Goyal 2009-01-15 09:04:05 EST
Committed in 78.29.EL . RPMS are available at http://people.redhat.com/vgoyal/rhel4/
Comment 12 errata-xmlrpc 2009-05-18 15:08:21 EDT
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.


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