|Summary:||msync(..., ..., MS_SYNC) returning before data written to disk|
|Product:||Red Hat Enterprise Linux 3||Reporter:||Chris Richards <chris.richards>|
|Component:||kernel||Assignee:||Larry Woodman <lwoodman>|
|Status:||CLOSED ERRATA||QA Contact:||Brian Brock <bbrock>|
|Version:||3.0||CC:||agk, bstevens, jturner, pcormier, peterm, petrides, riel, sct, tao, tburke, tkincaid|
|Fixed In Version:||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2005-04-22 20:17:34 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Bug Depends On:|
Description Chris Richards 2005-02-14 09:33:45 UTC
From Bugzilla Helper: User-Agent: Mozilla/5.0 (compatible; Konqueror/3.2) (KHTML, like Gecko) Description of problem: Calling msync(p, size, MS_SYNC) on a memory mapped file is not waiting for the data to be flushed to disk [eg a 128Mb chunk of data is claiming to be flushed in 1-2ms : cf 2.4.21-15 / 2.6.8-1.521 where the same test code takes 2-3s to do this] This means that there is no way for code to know that the data it has just written to a memory mapped file has actually made it to disk. Version-Release number of selected component (if applicable): kernel-2.4.21-20.EL and kernel-2.4.21-27.0.2.EL How reproducible: Always Steps to Reproduce: 1.mmap a (large-ish) file 2.write some data into the memory region 3.call msync with the MS_SYNC option 4.reboot the PC by hitting the power switch once msync has completed... [or time how long it takes to sync the data] 5.look at the contents of the file Actual Results: Data missing from file on disk (was present in file (ie disk buffers) prior to hitting power) Expected Results: msync should wait for the data to be written to disk when the MS_SYNC flag is used. Additional info:
Comment 2 Chris Richards 2005-02-16 17:41:03 UTC
linux-2.4.21-mmap-updates.patch lines 193/4 seem to be the problem. Upper limit test on end >= vma->vm_end fails when you sync the whole memory mapped area, but returns error (==0 ==success) so that you have no idea that it hasn't sync'ed anything at all.
Comment 7 Larry Woodman 2005-02-17 14:20:14 UTC
The patch to fix this problem was sent to rhkernel-list and has recieved the nexessary ACKs for inclusion in RHEL3-U5. Larry Woodman
Comment 8 Ernie Petrides 2005-02-19 10:23:21 UTC
A fix for this problem has just been committed to the RHEL3 U5 patch pool this evening (in kernel version 2.4.21-27.16.EL).
Comment 9 Ernie Petrides 2005-04-16 22:31:45 UTC
A fix for this problem has also been committed to the RHEL3 E5 patch pool this afternoon (in kernel version 2.4.21-27.0.4.EL).
Comment 10 Josh Bressers 2005-04-22 20:17:35 UTC
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 the 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. http://rhn.redhat.com/errata/RHSA-2005-293.html
Comment 11 Tim Powers 2005-05-18 13:29:17 UTC
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 the 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. http://rhn.redhat.com/errata/RHSA-2005-294.html