Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753685AbbKXMgy (ORCPT ); Tue, 24 Nov 2015 07:36:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:51620 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753032AbbKXMgo (ORCPT ); Tue, 24 Nov 2015 07:36:44 -0500 From: Vlastimil Babka To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman , Michal Hocko , Vlastimil Babka Subject: [PATCH v2 4/9] mm, page_owner: copy page owner info during migration Date: Tue, 24 Nov 2015 13:36:16 +0100 Message-Id: <1448368581-6923-5-git-send-email-vbabka@suse.cz> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1448368581-6923-1-git-send-email-vbabka@suse.cz> References: <1448368581-6923-1-git-send-email-vbabka@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4279 Lines: 119 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 --- 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 8e2eb15..6440daa 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 b1034f9..863a0f1 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 10a6a46..f571e55 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 -- 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/