From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 30 Jul 1998 15:20:20 -0400 (`eoyyyyp) From: "Benjamin C.R. LaHaise" Subject: Re: writable swap cache explained (it's weird) In-Reply-To: <35BF43AC.F0F0C14F@transmeta.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Bill Hawes Cc: Linux-kernel , Linus Torvalds , linux-mm@kvack.org List-ID: On Wed, 29 Jul 1998, Bill Hawes wrote: > To fix this I think we need to mark the whole mess as unswappable. It > won't work to just test for a writable pte to a shared page -- in this > case one of the sharings is only readable. So if the readable one gets > swapped out first, the remaining mappings would still be a problem. > > Anyone have any ideas for the best way to detect and handle this case? There are two options: a) disallow MAP_SHARED mappings of anonymous memory from /proc/self/mem b) implement shared anon mappings (a) sounds like the Obvious Thing To Do in the mmap method for /proc, but will break xdos. Wtf were they thinking in writing that insane code? Hmmm, this bug probably applies to 2.0 too.... in a much more subtle fashion. As for (b), I'll try to present code by Saturday, as it is a nice feature to add to our cap. =) (No, it's not going to be anything like the awful shm code.) -ben -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org