[Pvfs2-developers] Re: patch for client data corruption with 2.4kernels

[Rob Ross]

is there any way to do a quick verification that the buffer is still  
in the right place, on the kernel side, and then force a remapping?

rob

On Nov 21, 2008, at 11:19 AM, David Metheny wrote:

> I know this fixes RHEL3 (2.4 kernels) and the RHEL4 U6/U7 (2.6.9  
> kernels), but testing this with RHEL5 U2 (2.6.18-92.el5PAE) shows  
> that the memory is still being swapped out which would result in  
> client data corruption.
>
> From: pvfs2-developers-bounces at beowulf-underground.org [mailto:pvfs2-developers-bounces at beowulf-underground.org 
> ] On Behalf Of Bart Taylor
> Sent: Thursday, November 20, 2008 4:32 PM
> To: pvfs2-developers at beowulf-underground.org
> Subject: [Pvfs2-developers] Re: patch for client data corruption  
> with 2.4kernels
>
> I neglected the header file; attached is an additional patch to  
> catch it. Both of these patches should apply cleanly to head.
>
> Bart.
>
> On Thu, Nov 20, 2008 at 1:54 PM, Bart Taylor <batayl at gmail.com> wrote:
> Hey guys,
>
> This patch fixes a client data corruption issue on Linux 2.4  
> systems. We worked with Phil off-list and determined that the  
> kernel's mapped buffers are not staying pinned in memory as they  
> should be. We were able to verify that under heavy swapping the  
> pvfs2-client-core memory was being moved, invalidating the pointers.  
> This fix uses mlock to hold the two buffers in place, and we were  
> able to verify that it fixes the swapping issue. There are compile  
> time flags to ensure it is only added for Linux 2.4 systems.
>
> Bart.
>
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