From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754086AbdEIOkF (ORCPT ); Tue, 9 May 2017 10:40:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:51037 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753557AbdEIOkD (ORCPT ); Tue, 9 May 2017 10:40:03 -0400 Date: Tue, 9 May 2017 15:39:59 +0100 From: Mel Gorman To: Andy Lutomirski Cc: Dave Hansen , X86 ML , "linux-kernel@vger.kernel.org" , Borislav Petkov , Linus Torvalds , Andrew Morton , "linux-mm@kvack.org" , Rik van Riel , Nadav Amit , Michal Hocko , Sasha Levin Subject: Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic Message-ID: <20170509143959.u5e5vryzo26pdse4@suse.de> References: <983c5ee661d8fe8a70c596c4e77076d11ce3f80a.1494160201.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 09, 2017 at 06:02:49AM -0700, Andrew Lutomirski wrote: > On Mon, May 8, 2017 at 8:34 AM, Dave Hansen wrote: > > On 05/07/2017 05:38 AM, Andy Lutomirski wrote: > >> diff --git a/mm/rmap.c b/mm/rmap.c > >> index f6838015810f..2e568c82f477 100644 > >> --- a/mm/rmap.c > >> +++ b/mm/rmap.c > >> @@ -579,25 +579,12 @@ void page_unlock_anon_vma_read(struct anon_vma *anon_vma) > >> void try_to_unmap_flush(void) > >> { > >> struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; > >> - int cpu; > >> > >> if (!tlb_ubc->flush_required) > >> return; > >> > >> - cpu = get_cpu(); > >> - > >> - if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask)) { > >> - count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); > >> - local_flush_tlb(); > >> - trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL); > >> - } > >> - > >> - if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids) > >> - flush_tlb_others(&tlb_ubc->cpumask, NULL, 0, TLB_FLUSH_ALL); > >> - cpumask_clear(&tlb_ubc->cpumask); > >> tlb_ubc->flush_required = false; > >> tlb_ubc->writable = false; > >> - put_cpu(); > >> } > >> > >> /* Flush iff there are potentially writable TLB entries that can race with IO */ > >> @@ -613,7 +600,7 @@ static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) > >> { > >> struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; > >> > >> - cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm)); > >> + arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); > >> tlb_ubc->flush_required = true; > >> > >> /* > > > > Looking at this patch in isolation, how can this be safe? It removes > > TLB flushes from the generic code. Do other patches in the series fix > > this up? > > Hmm? Unless I totally screwed this up, this patch just moves the > flushes around -- it shouldn't remove any flushes. I think he's asking when or how arch_tlbbatch_flush gets called because it doesn't happen in try_to_unmap_flush(). -- Mel Gorman SUSE Labs