Re: ext3-0.9.15 against linux-2.4.14

From: Steven N. Hirsch (shirsch@adelphia.net)
Date: Tue Nov 06 2001 - 13:09:42 EST


On Tue, 6 Nov 2001, Andrew Morton wrote:

> Download details and documentation are at
>
> http://www.uow.edu.au/~andrewm/linux/ext3/
>
> Changes since ext3-0.9.13 (which was against linux-2.4.13):
>
> - For a long time, the ext3 patch has used a semaphore in the core
> kernel to prevent concurrent pagein and truncate of the same
> file. This was to prevent a race wherein the paging-in task
> would wake up after the truncate and would instantiate a page
> in the process's page tables which had attached buffers. This
> leads to a BUG() if the swapout code tries to swap the page out.
>
> This semaphore has been removed. The swapout code has been altered
> to simply detect and ignore these pages.
>
> This is an incredibly obscure and hard-to-hit situation. The testcase
> which used to trigger it can no longer do so. So if anyone sees the
> message "try_to_swap_out: page has buffers!", please shout out.

Andrew,

I have been getting thousands of these when the system was under heavy
load, but didn't realize it was from the ext3 code! I'm using Linus's
2.4.14-pre7 + ext3 patch from Neil Brown's site (the latter is identified
as "ZeroNineFourteen".) Would you like me to upgrade kernel and patch?

Steve

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