From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750785AbWD3MFL (ORCPT ); Sun, 30 Apr 2006 08:05:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750796AbWD3MFL (ORCPT ); Sun, 30 Apr 2006 08:05:11 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:28642 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S1750785AbWD3MFJ (ORCPT ); Sun, 30 Apr 2006 08:05:09 -0400 Date: Sun, 30 Apr 2006 14:04:22 +0200 From: Pavel Machek To: Andrew Morton Cc: Shaohua Li , linux-kernel@vger.kernel.org Subject: Re: [PATCH] don't use flush_tlb_all in suspend time Message-ID: <20060430120421.GA30024@elf.ucw.cz> References: <1146367462.21486.10.camel@sli10-desk.sh.intel.com> <20060430064505.GA5091@ucw.cz> <1146379596.8456.4.camel@sli10-desk.sh.intel.com> <20060429235721.1d081ea5.akpm@osdl.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060429235721.1d081ea5.akpm@osdl.org> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On So 29-04-06 23:57:21, Andrew Morton wrote: > Shaohua Li wrote: > > > > On Sun, 2006-04-30 at 06:45 +0000, Pavel Machek wrote: > > > Hi! > > > > > > > flush_tlb_all uses on_each_cpu, which will disable/enable interrupt. > > > > In suspend/resume time, this will make interrupt wrongly enabled. > > > > > > > diff -puN arch/i386/mm/init.c~flush_tlb_all_check arch/i386/mm/init.c > > > > --- linux-2.6.17-rc3/arch/i386/mm/init.c~flush_tlb_all_check 2006-04-29 08:47:05.000000000 +0800 > > > > +++ linux-2.6.17-rc3-root/arch/i386/mm/init.c 2006-04-29 08:48:15.000000000 +0800 > > > > @@ -420,7 +420,10 @@ void zap_low_mappings (void) > > > > #else > > > > set_pgd(swapper_pg_dir+i, __pgd(0)); > > > > #endif > > > > - flush_tlb_all(); > > > > + if (cpus_weight(cpu_online_map) == 1) > > > > + local_flush_tlb(); > > > > + else > > > > + flush_tlb_all(); > > > > } > > > > > > > > > > Either it is okay to enable interrupts here -> unneccessary and ugly > > > test, or it is not, and then we are broken in SMP case. > > It's not broken in SMP case, APs are offlined here in suspend/resume. > > > > In which case, how's about this? Certainly better, I'd say. > @@ -420,7 +421,14 @@ void zap_low_mappings (void) > #else > set_pgd(swapper_pg_dir+i, __pgd(0)); > #endif > - if (cpus_weight(cpu_online_map) == 1) > + /* > + * We can be called at suspend/resume time, with local interrupts > + * disabled. But flush_tlb_all() requires that local interrupts be > + * enabled. > + * > + * Happily, the APs are not yet started, so we can use local_flush_tlb() * in that case > + */ > + if (num_online_cpus() == 1) > local_flush_tlb(); > else > flush_tlb_all(); But this still scares. It means calling convention is "may enable interrupts with >1 cpu, may not with == 1 cpu". Pavel -- Thanks for all the (sleeping) penguins.