From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 11 Oct 1999 17:40:52 -0400 (EDT) From: Alexander Viro Subject: Re: locking question: do_mmap(), do_munmap() In-Reply-To: <14338.17669.163923.174022@dukat.scot.redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Stephen C. Tweedie" Cc: Manfred Spraul , Andrea Arcangeli , linux-kernel@vger.rutgers.edu, Ingo Molnar , linux-mm@kvack.org List-ID: On Mon, 11 Oct 1999, Stephen C. Tweedie wrote: > Hi, > > On Mon, 11 Oct 1999 12:05:23 -0400 (EDT), Alexander Viro > said: > > > On Mon, 11 Oct 1999, Stephen C. Tweedie wrote: > >> No, spinlocks would be ideal. The vma swapout codes _have_ to be > >> prepared for the vma to be destroyed as soon as we sleep. In fact, the > >> entire mm may disappear if the process happens to exit. Once we know > >> which page to write where, the swapout operation becomes a per-page > >> operation, not per-vma. > > > Aha, so you propose to drop it in ->swapout(), right? (after get_file() in > > filemap_write_page()... Ouch. Probably we'ld better lambda-expand the call > > in filemap_swapout() - the thing is called from other places too)... > > Right now it is the big kernel lock which is used for this, and the > scheduler drops it anyway for us. If anyone wants to replace that lock > with another spinlock, then yes, the swapout method would have to drop > it before doing anything which could block. And that is ugly: having > spinlocks unbalanced over function calls is a maintenance nightmare. Agreed, but the big lock does not (and IMHO should not) cover the vma list modifications. -- 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/