From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14338.25394.766252.528741@dukat.scot.redhat.com> Date: Mon, 11 Oct 1999 23:22:42 +0100 (BST) Subject: Re: locking question: do_mmap(), do_munmap() In-Reply-To: <38022640.3447ECA6@colorfullife.com> References: <38022640.3447ECA6@colorfullife.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Manfred Spraul Cc: Alexander Viro , "Stephen C. Tweedie" , Andrea Arcangeli , linux-kernel@vger.rutgers.edu, Ingo Molnar , linux-mm@kvack.org List-ID: Hi, On Mon, 11 Oct 1999 20:02:40 +0200, Manfred Spraul said: > What about something like a rw-semaphore which protects the vma list: > vma-list modifiers [ie merge_segments(), insert_vm_struct() and > do_munmap()] grab it exclusive, swapper grabs it "shared, starve > exclusive". Deadlock. Process A tries to do an mmap on mm A, gets the exclusive lock, tries to swap out from process B, and grabs mm B's shared lock. Process B in the mean time is doing the same thing and has an exclusive lock on mm B, and is trying to share-lock A. Whoops. > This should not dead-lock, Are you sure?! --Stephen -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/