Re: filecache/swapcache questions [RFC] [RFT] [PATCH] kanoj-mm12-2.3.8Fix swapoff races

["Stephen C. Tweedie" <sct@redhat.com>]

Hi,

On Tue, 29 Jun 1999 00:48:18 +0200 (CEST), Andrea Arcangeli
<andrea@suse.de> said:

> I thought a bit about that as well. I also coded a maybe possible
> solution. Look at this snapshot:

Much better: the synchronisation between the page fault and the swapper
is per-page, not per-mm, this way.  That way the swapper can afford
just to skip the one locked page rather than block for an mm lock.  My
only reservation is that it's a bit ugly to overload the "locked" bit
this way, but it's the only obvious test in try_to_swap_out that we can
use.  

Adding a new PG_Locked_PTE flag for the page, to indicate that somebody
is relying on this pte for COW operation and kswapd should skip it,
would be an alternative: it makes the intent much more clear (and keeps
PG_Locked purely for IO locking, which is really as it should be).

--Stephen

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