From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 3 May 2000 18:38:50 -0700 (PDT) From: Linus Torvalds Subject: Re: Oops in __free_pages_ok (pre7-1) (Long) (backtrace) In-Reply-To: <200005031608.JAA87583@google.engr.sgi.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Kanoj Sarcar Cc: Rajagopal Ananthanarayanan , linux-mm@kvack.org, "David S. Miller" List-ID: Ok, there's a pre7-4 out there that does the swapout with the page locked. I've given it some rudimentary testing, but certainly nothing really exotic. Please comment.. David pointed out that swapout_highmem can't really work, and he's right and wrong. It does work, but it works for rather undocumented reasons: it only gets invoced for anonymous dirty pages, and they are always cow-shared, so it's ok to "break" the page up into an "old" page and a "new" page with the same contents. Even though it's not legal in general. I'm not claiming that this fixes any known bugs, but it _does_ mean that we probably have the page locked in all fundamental cases where it really matters. If anybody finds a case where we play with the page-cached-ness (or similar) of a page without holding the page lock, please holler loudly. This way it should be easy to verify that yes, our coherency is fine. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/