From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752532AbbGUM1K (ORCPT ); Tue, 21 Jul 2015 08:27:10 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:35339 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751415AbbGUM1I (ORCPT ); Tue, 21 Jul 2015 08:27:08 -0400 Date: Tue, 21 Jul 2015 14:27:04 +0200 From: Michal Hocko To: Sasha Levin Cc: akpm@linux-foundation.org, mgorman@suse.de, riel@redhat.com, mingo@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: trace tlb flush after disabling preemption in try_to_unmap_flush Message-ID: <20150721122704.GL11967@dhcp22.suse.cz> References: <1437075339-32715-1-git-send-email-sasha.levin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437075339-32715-1-git-send-email-sasha.levin@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 16-07-15 15:35:39, Sasha Levin wrote: > Commit "mm: send one IPI per CPU to TLB flush all entries after unmapping > pages" added a trace_tlb_flush() while preemption was still enabled. This > means that we'll access smp_processor_id() which in turn will get us quite > a few warnings. > > Fix it by moving the trace to where the preemption is disabled, one line > down. > > Signed-off-by: Sasha Levin Reviewed-by: Michal Hocko > --- > > The diff is all lies: I've moved trace_tlb_flush() one line down rather > than get_cpu() a line up ;) > > mm/rmap.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 30812e9..63ba46c 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -613,9 +613,10 @@ void try_to_unmap_flush(void) > if (!tlb_ubc->flush_required) > return; > > + cpu = get_cpu(); > + > trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, -1UL); > > - cpu = get_cpu(); > if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask)) > percpu_flush_tlb_batch_pages(&tlb_ubc->cpumask); > > -- > 1.7.10.4 > > -- > 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/ -- Michal Hocko SUSE Labs