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From: Sasha Pachev <sasha@mysql.com>
Organization: MySQL
To: linux-kernel@vger.kernel.org, riel@conectiva.com.br
Subject: Suspected bug in shrink_caches()
Date: Wed, 2 Jan 2002 22:38:40 -0700
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Rik:

I am quite sure there is still a bug in shrink_caches(), at least there was 
one in 2.4.17-rc2. I have not tried later releases, but there is nothing in 
the changelog about the fixes anywhere near that area of the code, so I have 
to assume the problem is still there.

Here is how one can expose the bug:

 - disable kswapd and turn off all swap for simplicity
 - run two applications concurrently, one cache intenstive ( eg find / or 
simply create/initialize/read a large file), and the other RAM-intensive - 
allocate a large block and initialize it

When we get to the point where free memory starts running low, even though we 
may have something like 100 MB of cache, shrink_caches() fails to free up 
enough memory, which triggers the evil oom killer. Obviously, in the above 
situation the correct behaviour is to go on cache diet before considering the 
murders.

-- 
MySQL Development Team
For technical support contracts, visit https://order.mysql.com/
   __  ___     ___ ____  __ 
  /  |/  /_ __/ __/ __ \/ /   Sasha Pachev <sasha@mysql.com>
 / /|_/ / // /\ \/ /_/ / /__  MySQL AB, http://www.mysql.com/
/_/  /_/\_, /___/\___\_\___/  Provo, Utah, USA
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