Re: [PATCH] Fix to make check_pgt_cache work on !i386 architectures

Benjamin C.R. LaHaise (blah@kvack.org)
Sat, 1 Aug 1998 15:01:27 -0400 (EDT)


On Sat, 1 Aug 1998, Jakub Jelinek wrote:

> Where would you like to call it with argument 0?
> As we (David Miller and myself) explained a few times already, the nice
> thing about page table cache is that it requires now locking, so it is
> pretty fast. So you have to call it from the same CPU the cache is on, which
> is usually not the case with try_to_free_pages etc.

Ummm, but isn't allocation from the pgt cache *always* protected by the
holding of the global kernel lock? As far as I can see it, all paths to
allocating pgts (fork/clone, page faults, mmap & friends) start off by
getting an mmap semaphore and the kernel lock. Thus, there is will be no
race in emptying another cpu's pgt caches -- hence, Bill's patches are
safe. Of course, this probably won't be the case sometime in 2.3. =)

-ben

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