From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 17 Apr 2008 12:10:52 -0700 (PDT) From: Christoph Lameter Subject: Re: [PATCH 1 of 9] Lock the entire mm to prevent any mmu related operation to happen In-Reply-To: <20080417171443.GM17187@duo.random> Message-ID: References: <20080416163337.GJ22493@sgi.com> <20080417155157.GC17187@duo.random> <20080417163642.GE11364@sgi.com> <20080417171443.GM17187@duo.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Robin Holt , akpm@linux-foundation.org, Nick Piggin , Steve Wise , Peter Zijlstra , linux-mm@kvack.org, Kanoj Sarcar , Roland Dreier , Jack Steiner , linux-kernel@vger.kernel.org, Avi Kivity , kvm-devel@lists.sourceforge.net, general@lists.openfabrics.org, Hugh Dickins List-ID: On Thu, 17 Apr 2008, Andrea Arcangeli wrote: > Also note, EMM isn't using the clean hlist_del, it's implementing list > by hand (with zero runtime gain) so all the debugging may not be > existent in EMM, so if it's really a mm_lock race, and it only > triggers with mmu notifiers and not with EMM, it doesn't necessarily > mean EMM is bug free. If you've a full stack trace it would greatly > help to verify what is mangling over the list when the oops triggers. EMM was/is using a single linked list which allows atomic updates. Looked cleaner to me since doubly linked list must update two pointers. I have not seen docs on the locking so not sure why you use rcu operations here? Isnt the requirement to have either rmap locks or mmap_sem held enough to guarantee the consistency of the doubly linked list? -- 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-mm.org/ . Don't email: email@kvack.org