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SubjectRe: patch to trim page table cache
   Date: 	Fri, 17 Jul 1998 21:49:55 -0400
From: Bill Hawes <whawes@star.net>

The patch also corrects an apparent kernel locking problem in
arch/i386/kernel/process.c. The SMP version of sys_idle() doesn't
get the kernel lock before calling check_pgt_cache(), but since the
pgt quicklists don't have spinlock protection, the kernel lock is
necessary for SMP safety. I've moved the kernel lock upwards to
cover it.

UGH!!! They don't need spinlock protection!!!

The whole beauty of the design of the pgt_caches was that they _never_
need any locking even on SMP. They are local cpu cache lists, never
accessed from within' interrupts even.

Linus, please don't apply this.

Now, what this does point out, is that perhaps the machanism is not
commented properly, but actually I do remember this being explained in
the pgtable.h implementation level code at least on Sparc.

Later,
David S. Miller
davem@dm.cobaltmicro.com

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