kernel 2.4 inode/dentry cache not clearing on umount?

[Martin Bogomolni <martinbogo@gmail.com>]

Also .. David :

Are you saying that, on a system with 256Megs of ram, of which the
kernel is reporting only 3-4Mb free because the inode/dentry caches
are taking up most of the memory, and NO page/swap file....

char *p;
p = (char *) malloc( 64*1024*1024 );

I assure you that under these conditions, the malloc( ) will fail with NULL.

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Now, in the meantime I have discovered that merely unmounting the
filesystem is not enough to clear the dcache and icache.

However, if I unmount the filesystem then run:

cat /dev/hda > /dev/null

This causes the inode/dentry cache to finally shrink and the amount of
available free memory increases back to ~200Mb.   However, this
reduction does not immediately take place when the filesystem is
unmounted, and while the filesystem is mounted .. the inode/dentry
cache does not shrink and leaves only 3Mb of available free memory.