From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 2024F6B0003 for ; Fri, 22 Jun 2018 04:00:00 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id z5-v6so3286001pln.20 for ; Fri, 22 Jun 2018 01:00:00 -0700 (PDT) Received: from mga03.intel.com (mga03.intel.com. [134.134.136.65]) by mx.google.com with ESMTPS id d14-v6si7421906pln.206.2018.06.22.00.59.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Jun 2018 00:59:58 -0700 (PDT) Date: Fri, 22 Jun 2018 10:59:58 +0300 From: "Kirill A. Shutemov" Subject: Re: [v2 PATCH 1/2] mm: thp: register mm for khugepaged when merging vma for shmem Message-ID: <20180622075958.mzagr2ayufiuokea@black.fi.intel.com> References: <1529622949-75504-1-git-send-email-yang.shi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1529622949-75504-1-git-send-email-yang.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org List-ID: To: yang.shi@linux.alibaba.com Cc: hughd@google.com, vbabka@suse.cz, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Jun 21, 2018 at 11:15:48PM +0000, yang.shi@linux.alibaba.com wrote: > When merging anonymous page vma, if the size of vma can fit in at least > one hugepage, the mm will be registered for khugepaged for collapsing > THP in the future. > > But, it skips shmem vma. Doing so for shmem too, but not file-private > mapping, when merging vma in order to increase the odd to collapse > hugepage by khugepaged. > > Signed-off-by: Yang Shi > Cc: Hugh Dickins > Cc: Kirill A. Shutemov > Cc: Vlastimil Babka > --- > v1 --> 2: > * Exclude file-private mapping per Kirill's comment > > mm/khugepaged.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index d7b2a4b..9b0ec30 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -440,8 +440,12 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma, > * page fault if needed. > */ > return 0; > - if (vma->vm_ops || (vm_flags & VM_NO_KHUGEPAGED)) > - /* khugepaged not yet working on file or special mappings */ > + if ((vma->vm_ops && (!shmem_file(vma->vm_file) || vma->anon_vma)) || > + (vm_flags & VM_NO_KHUGEPAGED)) > + /* > + * khugepaged not yet working on non-shmem file or special > + * mappings. And, file-private shmem THP is not supported. > + */ > return 0; My point was that vma->anon_vma check above this one should not prevent collapse for shmem. Looking into this more, I think we should just replace all these checks with hugepage_vma_check() call. -- Kirill A. Shutemov