From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E957C6787C for ; Fri, 12 Oct 2018 17:35:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D708321470 for ; Fri, 12 Oct 2018 17:35:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D708321470 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727788AbeJMBI5 (ORCPT ); Fri, 12 Oct 2018 21:08:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726665AbeJMBI5 (ORCPT ); Fri, 12 Oct 2018 21:08:57 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 710117E9FD; Fri, 12 Oct 2018 17:35:23 +0000 (UTC) Received: from redhat.com (ovpn-125-5.rdu2.redhat.com [10.10.125.5]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 36EF27B52F; Fri, 12 Oct 2018 17:35:21 +0000 (UTC) Date: Fri, 12 Oct 2018 13:35:19 -0400 From: Jerome Glisse To: Andrea Arcangeli Cc: Zi Yan , linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , "Kirill A . Shutemov" , "H. Peter Anvin" , Anshuman Khandual , Dave Hansen , David Nellans , Ingo Molnar , Mel Gorman , Minchan Kim , Naoya Horiguchi , Thomas Gleixner , Vlastimil Babka , Michal Hocko Subject: Re: [PATCH] mm/thp: fix call to mmu_notifier in set_pmd_migration_entry() Message-ID: <20181012173518.GD6593@redhat.com> References: <20181012160953.5841-1-jglisse@redhat.com> <20181012172422.GA7395@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20181012172422.GA7395@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 12 Oct 2018 17:35:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 12, 2018 at 01:24:22PM -0400, Andrea Arcangeli wrote: > Hello, > > On Fri, Oct 12, 2018 at 12:20:54PM -0400, Zi Yan wrote: > > On 12 Oct 2018, at 12:09, jglisse@redhat.com wrote: > > > > > From: Jérôme Glisse > > > > > > Inside set_pmd_migration_entry() we are holding page table locks and > > > thus we can not sleep so we can not call invalidate_range_start/end() > > > > > > So remove call to mmu_notifier_invalidate_range_start/end() and add > > > call to mmu_notifier_invalidate_range(). Note that we are already > > Why the call to mmu_notifier_invalidate_range if we're under > range_start and followed by range_end? (it's not _range_only_end, if > it was _range_only_end the above would be needed) I wanted to be extra safe and accept to over invalidate. You are right that it is not strictly necessary. I am fine with removing it. > > > > calling mmu_notifier_invalidate_range_start/end() inside the function > > > calling set_pmd_migration_entry() (see try_to_unmap_one()). > > > > > > Signed-off-by: Jérôme Glisse > > > Reported-by: Andrea Arcangeli > > > Cc: Andrew Morton > > > Cc: Greg Kroah-Hartman > > > Cc: Zi Yan > > > Cc: Kirill A. Shutemov > > > Cc: "H. Peter Anvin" > > > Cc: Anshuman Khandual > > > Cc: Dave Hansen > > > Cc: David Nellans > > > Cc: Ingo Molnar > > > Cc: Mel Gorman > > > Cc: Minchan Kim > > > Cc: Naoya Horiguchi > > > Cc: Thomas Gleixner > > > Cc: Vlastimil Babka > > > Cc: Michal Hocko > > > Cc: Andrea Arcangeli > > > --- > > > mm/huge_memory.c | 7 +------ > > > 1 file changed, 1 insertion(+), 6 deletions(-) > > > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > > index 533f9b00147d..93cb80fe12cb 100644 > > > --- a/mm/huge_memory.c > > > +++ b/mm/huge_memory.c > > > @@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > > if (!(pvmw->pmd && !pvmw->pte)) > > > return; > > > > > > - mmu_notifier_invalidate_range_start(mm, address, > > > - address + HPAGE_PMD_SIZE); > > > - > > > flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); > > > pmdval = *pvmw->pmd; > > > pmdp_invalidate(vma, address, pvmw->pmd); > > > @@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, > > > if (pmd_soft_dirty(pmdval)) > > > pmdswp = pmd_swp_mksoft_dirty(pmdswp); > > > set_pmd_at(mm, address, pvmw->pmd, pmdswp); > > > + mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE); > > It's not obvious why it's needed, if it's needed maybe a comment can > be added. We can remove it. Should i post a v2 without it ? Cheers, Jérôme