From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 1FE3828073C for ; Tue, 9 May 2017 13:13:28 -0400 (EDT) Received: by mail-pg0-f72.google.com with SMTP id i63so4430757pgd.15 for ; Tue, 09 May 2017 10:13:28 -0700 (PDT) Received: from mga06.intel.com (mga06.intel.com. [134.134.136.31]) by mx.google.com with ESMTPS id g7si461255plk.325.2017.05.09.10.13.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 May 2017 10:13:27 -0700 (PDT) Subject: Re: [RFC 03/10] x86/mm: Make the batched unmap TLB flush API more generic References: <983c5ee661d8fe8a70c596c4e77076d11ce3f80a.1494160201.git.luto@kernel.org> From: Dave Hansen Message-ID: Date: Tue, 9 May 2017 10:13:26 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andy Lutomirski Cc: X86 ML , "linux-kernel@vger.kernel.org" , Borislav Petkov , Linus Torvalds , Andrew Morton , Mel Gorman , "linux-mm@kvack.org" , Rik van Riel , Nadav Amit , Michal Hocko , Sasha Levin On 05/09/2017 06:02 AM, Andy 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. This takes a flush out of try_to_unmap_flush(). It adds code for arch_tlbbatch_flush(), but not *calls* to arch_tlbbatch_flush() that I can see. I actually don't see _any_ in the whole series in a quick grepping. Am I just missing them? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org