Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755928Ab1EJAUm (ORCPT ); Mon, 9 May 2011 20:20:42 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:32856 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753105Ab1EJAUl (ORCPT ); Mon, 9 May 2011 20:20:41 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Stephen Wilson Subject: Re: [PATCH 2/8] mm: use walk_page_range() instead of custom page table walking code Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Alexander Viro , Hugh Dickins , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: <20110509193650.GA2865@wicker.gateway.2wire.net> References: <20110509164034.164C.A69D9226@jp.fujitsu.com> <20110509193650.GA2865@wicker.gateway.2wire.net> Message-Id: <20110510092219.168E.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.56.05 [ja] Date: Tue, 10 May 2011 09:20:38 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5272 Lines: 161 > On Mon, May 09, 2011 at 04:38:49PM +0900, KOSAKI Motohiro wrote: > > Hello, > > > > sorry for the long delay. > > Please, no apologies. Thank you for the review! > > > > In the specific case of show_numa_map(), the custom page table walking > > > logic implemented in mempolicy.c does not provide any special service > > > beyond that provided by walk_page_range(). > > > > > > Also, converting show_numa_map() to use the generic routine decouples > > > the function from mempolicy.c, allowing it to be moved out of the mm > > > subsystem and into fs/proc. > > > > > > Signed-off-by: Stephen Wilson > > > --- > > > mm/mempolicy.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++------- > > > 1 files changed, 46 insertions(+), 7 deletions(-) > > > > > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > > > index 5bfb03e..dfe27e3 100644 > > > --- a/mm/mempolicy.c > > > +++ b/mm/mempolicy.c > > > @@ -2568,6 +2568,22 @@ static void gather_stats(struct page *page, void *private, int pte_dirty) > > > md->node[page_to_nid(page)]++; > > > } > > > > > > +static int gather_pte_stats(pte_t *pte, unsigned long addr, > > > + unsigned long pte_size, struct mm_walk *walk) > > > +{ > > > + struct page *page; > > > + > > > + if (pte_none(*pte)) > > > + return 0; > > > + > > > + page = pte_page(*pte); > > > + if (!page) > > > + return 0; > > > > original check_pte_range() has following logic. > > > > orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > > do { > > struct page *page; > > int nid; > > > > if (!pte_present(*pte)) > > continue; > > page = vm_normal_page(vma, addr, *pte); > > if (!page) > > continue; > > /* > > * vm_normal_page() filters out zero pages, but there might > > * still be PageReserved pages to skip, perhaps in a VDSO. > > * And we cannot move PageKsm pages sensibly or safely yet. > > */ > > if (PageReserved(page) || PageKsm(page)) > > continue; > > gather_stats(page, private, pte_dirty(*pte)); > > > > Why did you drop a lot of check? Is it safe? > > I must have been confused. For one, walk_page_range() does not even > lock the pmd entry when iterating over the pte's. I completely > overlooked that fact and so with that, the series is totally broken. > > I am currently testing a slightly reworked set based on the following > variation. When finished I will send v2 of the series which will > address all issues raised so far. > > Thanks again for the review! > > > > From 013a1e0fc96f8370339209f16d81df4ded40dbf2 Mon Sep 17 00:00:00 2001 > From: Stephen Wilson > Date: Mon, 9 May 2011 14:39:27 -0400 > Subject: [PATCH] mm: use walk_page_range() instead of custom page table > walking code > > Converting show_numa_map() to use the generic routine decouples > the function from mempolicy.c, allowing it to be moved out of the mm > subsystem and into fs/proc. > > Also, include KSM pages in /proc/pid/numa_maps statistics. The pagewalk > logic implemented by check_pte_range() failed to account for such pages > as they were not applicable to the page migration case. Seems very reasonable change. > > Signed-off-by: Stephen Wilson > --- > mm/mempolicy.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++----- > 1 files changed, 68 insertions(+), 7 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 5bfb03e..945e85d 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -2531,6 +2531,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context) > } > > struct numa_maps { > + struct vm_area_struct *vma; > unsigned long pages; > unsigned long anon; > unsigned long active; > @@ -2568,6 +2569,41 @@ static void gather_stats(struct page *page, void *private, int pte_dirty) > md->node[page_to_nid(page)]++; > } > > +static int gather_pte_stats(pmd_t *pmd, unsigned long addr, > + unsigned long end, struct mm_walk *walk) > +{ > + struct numa_maps *md; > + spinlock_t *ptl; > + pte_t *orig_pte; > + pte_t *pte; > + > + md = walk->private; > + orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > + do { > + struct page *page; > + int nid; > + > + if (!pte_present(*pte)) > + continue; > + > + page = vm_normal_page(md->vma, addr, *pte); > + if (!page) > + continue; > + > + if (PageReserved(page)) > + continue; > + > + nid = page_to_nid(page); > + if (!node_isset(nid, node_states[N_HIGH_MEMORY])) > + continue; > + > + gather_stats(page, md, pte_dirty(*pte)); > + > + } while (pte++, addr += PAGE_SIZE, addr != end); > + pte_unmap_unlock(orig_pte, ptl); > + return 0; > +} Looks completely good. Reviewed-by KOSAKI Motohiro Thank you for great work! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/