From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753564AbbDANTa (ORCPT ); Wed, 1 Apr 2015 09:19:30 -0400 Received: from mta-out1.inet.fi ([62.71.2.203]:38825 "EHLO jenni2.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752997AbbDANT2 (ORCPT ); Wed, 1 Apr 2015 09:19:28 -0400 Date: Wed, 1 Apr 2015 16:19:07 +0300 From: "Kirill A. Shutemov" To: "Aneesh Kumar K.V" Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , Johannes Weiner , Michal Hocko , Jerome Marchand , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv4 19/24] thp, mm: use migration entries to freeze page counts on split Message-ID: <20150401131907.GE17153@node.dhcp.inet.fi> References: <1425486792-93161-1-git-send-email-kirill.shutemov@linux.intel.com> <1425486792-93161-20-git-send-email-kirill.shutemov@linux.intel.com> <87h9t2le07.fsf@linux.vnet.ibm.com> <20150330152652.GC5849@node.dhcp.inet.fi> <87bnjalc9g.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87bnjalc9g.fsf@linux.vnet.ibm.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 30, 2015 at 09:15:47PM +0530, Aneesh Kumar K.V wrote: > "Kirill A. Shutemov" writes: > > > On Mon, Mar 30, 2015 at 08:38:08PM +0530, Aneesh Kumar K.V wrote: > >> .... > >> .... > >> +static void freeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + struct vm_area_struct *vma; > >> > + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > >> > >> So this get called only with head page, We also do > >> BUG_ON(PageTail(page)) in the caller. But > >> > >> > >> > + unsigned long addr, haddr; > >> > + unsigned long mmun_start, mmun_end; > >> > + pgd_t *pgd; > >> > + pud_t *pud; > >> > + pmd_t *pmd; > >> > + pte_t *start_pte, *pte; > >> > + spinlock_t *ptl; > >> ...... > >> > >> > >> > + > >> > +static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + pgoff_t pgoff = page_to_pgoff(page); > >> > >> Why ? Can this get called for tail pages ? > > > > It cannot. pgoff is offset of head page (and therefore whole compound > > page) within rmapping. > > > > This we can use > > pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > > similar to what we do in freeze_page(). The difference between > freeze/unfreeze confused me. Fair enough. Will fix. -- Kirill A. Shutemov From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f170.google.com (mail-wi0-f170.google.com [209.85.212.170]) by kanga.kvack.org (Postfix) with ESMTP id 1AC016B0038 for ; Wed, 1 Apr 2015 09:19:19 -0400 (EDT) Received: by widdi4 with SMTP id di4so44600931wid.0 for ; Wed, 01 Apr 2015 06:19:18 -0700 (PDT) Received: from jenni2.inet.fi (mta-out1.inet.fi. [62.71.2.203]) by mx.google.com with ESMTP id a2si3273465wjs.97.2015.04.01.06.19.17 for ; Wed, 01 Apr 2015 06:19:17 -0700 (PDT) Date: Wed, 1 Apr 2015 16:19:07 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCHv4 19/24] thp, mm: use migration entries to freeze page counts on split Message-ID: <20150401131907.GE17153@node.dhcp.inet.fi> References: <1425486792-93161-1-git-send-email-kirill.shutemov@linux.intel.com> <1425486792-93161-20-git-send-email-kirill.shutemov@linux.intel.com> <87h9t2le07.fsf@linux.vnet.ibm.com> <20150330152652.GC5849@node.dhcp.inet.fi> <87bnjalc9g.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87bnjalc9g.fsf@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Aneesh Kumar K.V" Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Dave Hansen , Hugh Dickins , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , Johannes Weiner , Michal Hocko , Jerome Marchand , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Mon, Mar 30, 2015 at 09:15:47PM +0530, Aneesh Kumar K.V wrote: > "Kirill A. Shutemov" writes: > > > On Mon, Mar 30, 2015 at 08:38:08PM +0530, Aneesh Kumar K.V wrote: > >> .... > >> .... > >> +static void freeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + struct vm_area_struct *vma; > >> > + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > >> > >> So this get called only with head page, We also do > >> BUG_ON(PageTail(page)) in the caller. But > >> > >> > >> > + unsigned long addr, haddr; > >> > + unsigned long mmun_start, mmun_end; > >> > + pgd_t *pgd; > >> > + pud_t *pud; > >> > + pmd_t *pmd; > >> > + pte_t *start_pte, *pte; > >> > + spinlock_t *ptl; > >> ...... > >> > >> > >> > + > >> > +static void unfreeze_page(struct anon_vma *anon_vma, struct page *page) > >> > +{ > >> > + struct anon_vma_chain *avc; > >> > + pgoff_t pgoff = page_to_pgoff(page); > >> > >> Why ? Can this get called for tail pages ? > > > > It cannot. pgoff is offset of head page (and therefore whole compound > > page) within rmapping. > > > > This we can use > > pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); > > similar to what we do in freeze_page(). The difference between > freeze/unfreeze confused me. Fair enough. Will fix. -- Kirill A. Shutemov -- 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