Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964977AbVKOSGt (ORCPT ); Tue, 15 Nov 2005 13:06:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964983AbVKOSGt (ORCPT ); Tue, 15 Nov 2005 13:06:49 -0500 Received: from smtp.osdl.org ([65.172.181.4]:29600 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S964977AbVKOSGs (ORCPT ); Tue, 15 Nov 2005 13:06:48 -0500 Date: Tue, 15 Nov 2005 10:02:48 -0800 From: Andrew Morton To: Christoph Lameter Cc: torvalds@osdl.org, marcelo.tosatti@cyclades.com, kravetz@us.ibm.com, raybry@mpdtxmail.amd.com, lee.schermerhorn@hp.com, linux-kernel@vger.kernel.org, magnus.damm@gmail.com, pj@sgi.com, haveblue@us.ibm.com, kamezawa.hiroyu@jp.fujitsu.com Subject: Re: [PATCH 1/5] Swap Migration V5: LRU operations Message-Id: <20051115100248.5ba2383d.akpm@osdl.org> In-Reply-To: References: <20051101031239.12488.76816.sendpatchset@schroedinger.engr.sgi.com> <20051101031244.12488.38211.sendpatchset@schroedinger.engr.sgi.com> <20051114214415.1e107c7b.akpm@osdl.org> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1494 Lines: 39 Christoph Lameter wrote: > > On Mon, 14 Nov 2005, Andrew Morton wrote: > > > > +int isolate_lru_page(struct page *page) > > > +{ > > > + int rc = 0; > > > + struct zone *zone = page_zone(page); > > > + > > > +redo: > > > + spin_lock_irq(&zone->lru_lock); > > > + rc = __isolate_lru_page(zone, page); > > > + spin_unlock_irq(&zone->lru_lock); > > > + if (rc == 0) { > > > + /* > > > + * Maybe this page is still waiting for a cpu to drain it > > > + * from one of the lru lists? > > > + */ > > > + smp_call_function(&lru_add_drain_per_cpu, NULL, 0 , 1); > > > > lru_add_drain() ends up doing spin_unlock_irq(), so we'll enable interrupts > > within the smp_call_function() handler. Is that legal on all > > architectures? > > isolate_lru_pages() is only called within a process context in the swap > migration patches. The hotplug folks may have to address this if they want > to isolate pages from interrupts etc. But lru_add_drain_per_cpu() will be called from interrupt context: the IPI handler. I'm asking whether it is safe for the IPI handler to reenable interupts on all architectures. It might be so, but I don't recall ever having seen it discussed, nor have I seen code which does it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/