From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 3 May 2000 09:14:28 -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 List-ID: On Wed, 3 May 2000, Kanoj Sarcar wrote: > > So "is_page_shared()" can be entirely crap. And can tell shrink_mmap() > > Not really ... look at other places that call is_page_shared, they all > hold the pagelock. shrink_mmap does not bother with is_page_shared logic. That wasn't my argument. My argument is that yes, the _callers_ of is_page_shared() all hold the page lock. No question about that. But the things that is_page_shared() actually tests can be modified without holding the page lock, so the page lock doesn't actually _protect_ it. See? So the callers might as well hold one of the networking spinlocks - it just doesn't matter as a lock, because the places that modify the stuff do not care about the lock.. And that is fishy. 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/