Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751796AbdCCK1N (ORCPT ); Fri, 3 Mar 2017 05:27:13 -0500 Received: from mga07.intel.com ([134.134.136.100]:52394 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751449AbdCCK1K (ORCPT ); Fri, 3 Mar 2017 05:27:10 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,236,1484035200"; d="scan'208";a="1137412383" Date: Fri, 3 Mar 2017 13:26:36 +0300 From: "Kirill A. Shutemov" To: Hillf Danton , "Aneesh Kumar K.V" Cc: "'Andrea Arcangeli'" , "'Andrew Morton'" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "'Minchan Kim'" Subject: Re: [PATCH 3/4] thp: fix MADV_DONTNEED vs. MADV_FREE race Message-ID: <20170303102636.bhd2zhtpds4mt62a@black.fi.intel.com> References: <20170302151034.27829-1-kirill.shutemov@linux.intel.com> <20170302151034.27829-4-kirill.shutemov@linux.intel.com> <07b101d293df$ed8c9850$c8a5c8f0$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <07b101d293df$ed8c9850$c8a5c8f0$@alibaba-inc.com> User-Agent: NeoMutt/20161126 (1.7.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2513 Lines: 72 On Fri, Mar 03, 2017 at 01:35:11PM +0800, Hillf Danton wrote: > > On March 02, 2017 11:11 PM Kirill A. Shutemov wrote: > > > > Basically the same race as with numa balancing in change_huge_pmd(), but > > a bit simpler to mitigate: we don't need to preserve dirty/young flags > > here due to MADV_FREE functionality. > > > > Signed-off-by: Kirill A. Shutemov > > Cc: Minchan Kim > > --- > > mm/huge_memory.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index bb2b3646bd78..324217c31ec9 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -1566,8 +1566,6 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > > deactivate_page(page); > > > > if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { > > - orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, > > - tlb->fullmm); > > orig_pmd = pmd_mkold(orig_pmd); > > orig_pmd = pmd_mkclean(orig_pmd); > > > $ grep -n set_pmd_at linux-4.10/arch/powerpc/mm/pgtable-book3s64.c > > /* > * set a new huge pmd. We should not be called for updating > * an existing pmd entry. That should go via pmd_hugepage_update. > */ > void set_pmd_at(struct mm_struct *mm, unsigned long addr, +Aneesh. Urgh... Power is special again. I think this should work fine. >From 056914fa025992c0a2212aee057c26307ce60238 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 2 Mar 2017 16:47:45 +0300 Subject: [PATCH] thp: fix MADV_DONTNEED vs. MADV_FREE race Basically the same race as with numa balancing in change_huge_pmd(), but a bit simpler to mitigate: we don't need to preserve dirty/young flags here due to MADV_FREE functionality. Signed-off-by: Kirill A. Shutemov Cc: Minchan Kim --- mm/huge_memory.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index bb2b3646bd78..23c1b3d58cf4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1566,8 +1566,7 @@ bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, deactivate_page(page); if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { - orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, - tlb->fullmm); + pmdp_invalidate(vma, addr, pmd); orig_pmd = pmd_mkold(orig_pmd); orig_pmd = pmd_mkclean(orig_pmd); -- Kirill A. Shutemov