From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752872AbcAGKpG (ORCPT ); Thu, 7 Jan 2016 05:45:06 -0500 Received: from mail-wm0-f51.google.com ([74.125.82.51]:38758 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752007AbcAGKpB (ORCPT ); Thu, 7 Jan 2016 05:45:01 -0500 Date: Thu, 7 Jan 2016 11:44:58 +0100 From: Michal Hocko To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman , Hugh Dickins Subject: Re: [PATCH v3 11/14] mm, page_owner: copy page owner info during migration Message-ID: <20160107104458.GI27868@dhcp22.suse.cz> References: <1450429406-7081-1-git-send-email-vbabka@suse.cz> <1450429406-7081-12-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1450429406-7081-12-git-send-email-vbabka@suse.cz> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 18-12-15 10:03:23, Vlastimil Babka wrote: > The page_owner mechanism stores gfp_flags of an allocation and stack trace > that lead to it. During page migration, the original information is > practically replaced by the allocation of free page as the migration target. > Arguably this is less useful and might lead to all the page_owner info for > migratable pages gradually converge towards compaction or numa balancing > migrations. It has also lead to inaccuracies such as one fixed by commit > e2cfc91120fa ("mm/page_owner: set correct gfp_mask on page_owner"). > > This patch thus introduces copying the page_owner info during migration. > However, since the fact that the page has been migrated from its original > place might be useful for debugging, the next patch will introduce a way to > track that information as well. > > Signed-off-by: Vlastimil Babka > Cc: Joonsoo Kim > Cc: Minchan Kim > Cc: Sasha Levin > Cc: "Kirill A. Shutemov" > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Hugh Dickins Acked-by: Michal Hocko > --- > include/linux/page_owner.h | 10 +++++++++- > mm/migrate.c | 3 +++ > mm/page_owner.c | 25 +++++++++++++++++++++++++ > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h > index 8e2eb153c7b9..6440daab4ef8 100644 > --- a/include/linux/page_owner.h > +++ b/include/linux/page_owner.h > @@ -11,6 +11,7 @@ extern void __reset_page_owner(struct page *page, unsigned int order); > extern void __set_page_owner(struct page *page, > unsigned int order, gfp_t gfp_mask); > extern gfp_t __get_page_owner_gfp(struct page *page); > +extern void __copy_page_owner(struct page *oldpage, struct page *newpage); > > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -32,6 +33,11 @@ static inline gfp_t get_page_owner_gfp(struct page *page) > else > return 0; > } > +static inline void copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > + if (static_branch_unlikely(&page_owner_inited)) > + __copy_page_owner(oldpage, newpage); > +} > #else > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -44,6 +50,8 @@ static inline gfp_t get_page_owner_gfp(struct page *page) > { > return 0; > } > - > +static inline void copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > +} > #endif /* CONFIG_PAGE_OWNER */ > #endif /* __LINUX_PAGE_OWNER_H */ > diff --git a/mm/migrate.c b/mm/migrate.c > index b1034f9c77e7..863a0f1fe23f 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -38,6 +38,7 @@ > #include > #include > #include > +#include > > #include > > @@ -578,6 +579,8 @@ void migrate_page_copy(struct page *newpage, struct page *page) > */ > if (PageWriteback(newpage)) > end_page_writeback(newpage); > + > + copy_page_owner(page, newpage); > } > > /************************************************************ > diff --git a/mm/page_owner.c b/mm/page_owner.c > index c8ea1361146e..a390d2665df2 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -84,6 +84,31 @@ gfp_t __get_page_owner_gfp(struct page *page) > return page_ext->gfp_mask; > } > > +void __copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > + struct page_ext *old_ext = lookup_page_ext(oldpage); > + struct page_ext *new_ext = lookup_page_ext(newpage); > + int i; > + > + new_ext->order = old_ext->order; > + new_ext->gfp_mask = old_ext->gfp_mask; > + new_ext->nr_entries = old_ext->nr_entries; > + > + for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++) > + new_ext->trace_entries[i] = old_ext->trace_entries[i]; > + > + /* > + * We don't clear the bit on the oldpage as it's going to be freed > + * after migration. Until then, the info can be useful in case of > + * a bug, and the overal stats will be off a bit only temporarily. > + * Also, migrate_misplaced_transhuge_page() can still fail the > + * migration and then we want the oldpage to retain the info. But > + * in that case we also don't need to explicitly clear the info from > + * the new page, which will be freed. > + */ > + __set_bit(PAGE_EXT_OWNER, &new_ext->flags); > +} > + > static ssize_t > print_page_owner(char __user *buf, size_t count, unsigned long pfn, > struct page *page, struct page_ext *page_ext) > -- > 2.6.3 -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f45.google.com (mail-wm0-f45.google.com [74.125.82.45]) by kanga.kvack.org (Postfix) with ESMTP id 8ED14828DE for ; Thu, 7 Jan 2016 05:45:01 -0500 (EST) Received: by mail-wm0-f45.google.com with SMTP id u188so92922646wmu.1 for ; Thu, 07 Jan 2016 02:45:01 -0800 (PST) Received: from mail-wm0-f41.google.com (mail-wm0-f41.google.com. [74.125.82.41]) by mx.google.com with ESMTPS id 126si18898719wma.118.2016.01.07.02.44.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jan 2016 02:45:00 -0800 (PST) Received: by mail-wm0-f41.google.com with SMTP id l65so91597626wmf.1 for ; Thu, 07 Jan 2016 02:44:59 -0800 (PST) Date: Thu, 7 Jan 2016 11:44:58 +0100 From: Michal Hocko Subject: Re: [PATCH v3 11/14] mm, page_owner: copy page owner info during migration Message-ID: <20160107104458.GI27868@dhcp22.suse.cz> References: <1450429406-7081-1-git-send-email-vbabka@suse.cz> <1450429406-7081-12-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1450429406-7081-12-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman , Hugh Dickins On Fri 18-12-15 10:03:23, Vlastimil Babka wrote: > The page_owner mechanism stores gfp_flags of an allocation and stack trace > that lead to it. During page migration, the original information is > practically replaced by the allocation of free page as the migration target. > Arguably this is less useful and might lead to all the page_owner info for > migratable pages gradually converge towards compaction or numa balancing > migrations. It has also lead to inaccuracies such as one fixed by commit > e2cfc91120fa ("mm/page_owner: set correct gfp_mask on page_owner"). > > This patch thus introduces copying the page_owner info during migration. > However, since the fact that the page has been migrated from its original > place might be useful for debugging, the next patch will introduce a way to > track that information as well. > > Signed-off-by: Vlastimil Babka > Cc: Joonsoo Kim > Cc: Minchan Kim > Cc: Sasha Levin > Cc: "Kirill A. Shutemov" > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Hugh Dickins Acked-by: Michal Hocko > --- > include/linux/page_owner.h | 10 +++++++++- > mm/migrate.c | 3 +++ > mm/page_owner.c | 25 +++++++++++++++++++++++++ > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h > index 8e2eb153c7b9..6440daab4ef8 100644 > --- a/include/linux/page_owner.h > +++ b/include/linux/page_owner.h > @@ -11,6 +11,7 @@ extern void __reset_page_owner(struct page *page, unsigned int order); > extern void __set_page_owner(struct page *page, > unsigned int order, gfp_t gfp_mask); > extern gfp_t __get_page_owner_gfp(struct page *page); > +extern void __copy_page_owner(struct page *oldpage, struct page *newpage); > > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -32,6 +33,11 @@ static inline gfp_t get_page_owner_gfp(struct page *page) > else > return 0; > } > +static inline void copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > + if (static_branch_unlikely(&page_owner_inited)) > + __copy_page_owner(oldpage, newpage); > +} > #else > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -44,6 +50,8 @@ static inline gfp_t get_page_owner_gfp(struct page *page) > { > return 0; > } > - > +static inline void copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > +} > #endif /* CONFIG_PAGE_OWNER */ > #endif /* __LINUX_PAGE_OWNER_H */ > diff --git a/mm/migrate.c b/mm/migrate.c > index b1034f9c77e7..863a0f1fe23f 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -38,6 +38,7 @@ > #include > #include > #include > +#include > > #include > > @@ -578,6 +579,8 @@ void migrate_page_copy(struct page *newpage, struct page *page) > */ > if (PageWriteback(newpage)) > end_page_writeback(newpage); > + > + copy_page_owner(page, newpage); > } > > /************************************************************ > diff --git a/mm/page_owner.c b/mm/page_owner.c > index c8ea1361146e..a390d2665df2 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -84,6 +84,31 @@ gfp_t __get_page_owner_gfp(struct page *page) > return page_ext->gfp_mask; > } > > +void __copy_page_owner(struct page *oldpage, struct page *newpage) > +{ > + struct page_ext *old_ext = lookup_page_ext(oldpage); > + struct page_ext *new_ext = lookup_page_ext(newpage); > + int i; > + > + new_ext->order = old_ext->order; > + new_ext->gfp_mask = old_ext->gfp_mask; > + new_ext->nr_entries = old_ext->nr_entries; > + > + for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++) > + new_ext->trace_entries[i] = old_ext->trace_entries[i]; > + > + /* > + * We don't clear the bit on the oldpage as it's going to be freed > + * after migration. Until then, the info can be useful in case of > + * a bug, and the overal stats will be off a bit only temporarily. > + * Also, migrate_misplaced_transhuge_page() can still fail the > + * migration and then we want the oldpage to retain the info. But > + * in that case we also don't need to explicitly clear the info from > + * the new page, which will be freed. > + */ > + __set_bit(PAGE_EXT_OWNER, &new_ext->flags); > +} > + > static ssize_t > print_page_owner(char __user *buf, size_t count, unsigned long pfn, > struct page *page, struct page_ext *page_ext) > -- > 2.6.3 -- Michal Hocko SUSE Labs -- 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