From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1AF2C3A59E for ; Tue, 20 Aug 2019 13:18:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A170722DA7 for ; Tue, 20 Aug 2019 13:18:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730039AbfHTNSr (ORCPT ); Tue, 20 Aug 2019 09:18:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:56362 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727006AbfHTNSk (ORCPT ); Tue, 20 Aug 2019 09:18:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E9EB9AD54; Tue, 20 Aug 2019 13:18:38 +0000 (UTC) From: Vlastimil Babka To: linux-mm@kvack.org, Andrew Morton Cc: linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Michal Hocko , Mel Gorman , Matthew Wilcox , Vlastimil Babka Subject: [PATCH v2 3/4] mm, page_owner: keep owner info when freeing the page Date: Tue, 20 Aug 2019 15:18:27 +0200 Message-Id: <20190820131828.22684-4-vbabka@suse.cz> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190820131828.22684-1-vbabka@suse.cz> References: <20190820131828.22684-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For debugging purposes it might be useful to keep the owner info even after page has been freed, and include it in e.g. dump_page() when detecting a bad page state. For that, change the PAGE_EXT_OWNER flag meaning to "page owner info has been set at least once" and add new PAGE_EXT_OWNER_ACTIVE for tracking whether page is supposed to be currently tracked allocated or free. Adjust dump_page() accordingly, distinguishing free and allocated pages. In the page_owner debugfs file, keep printing only allocated pages so that existing scripts are not confused, and also because free pages are irrelevant for the memory statistics or leak detection that's the typical use case of the file, anyway. Signed-off-by: Vlastimil Babka --- include/linux/page_ext.h | 1 + mm/page_owner.c | 34 ++++++++++++++++++++++++---------- 2 files changed, 25 insertions(+), 10 deletions(-) diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h index 09592951725c..682fd465df06 100644 --- a/include/linux/page_ext.h +++ b/include/linux/page_ext.h @@ -18,6 +18,7 @@ struct page_ext_operations { enum page_ext_flags { PAGE_EXT_OWNER, + PAGE_EXT_OWNER_ACTIVE, #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT) PAGE_EXT_YOUNG, PAGE_EXT_IDLE, diff --git a/mm/page_owner.c b/mm/page_owner.c index 813fcb70547b..4a48e018dbdf 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -111,7 +111,7 @@ void __reset_page_owner(struct page *page, unsigned int order) page_ext = lookup_page_ext(page + i); if (unlikely(!page_ext)) continue; - __clear_bit(PAGE_EXT_OWNER, &page_ext->flags); + __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); } } @@ -168,6 +168,7 @@ static inline void __set_page_owner_handle(struct page *page, page_owner->gfp_mask = gfp_mask; page_owner->last_migrate_reason = -1; __set_bit(PAGE_EXT_OWNER, &page_ext->flags); + __set_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); page_ext = lookup_page_ext(page + i); } @@ -243,6 +244,7 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage) * the new page, which will be freed. */ __set_bit(PAGE_EXT_OWNER, &new_ext->flags); + __set_bit(PAGE_EXT_OWNER_ACTIVE, &new_ext->flags); } void pagetypeinfo_showmixedcount_print(struct seq_file *m, @@ -302,7 +304,7 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, if (unlikely(!page_ext)) continue; - if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) + if (!test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags)) continue; page_owner = get_page_owner(page_ext); @@ -413,21 +415,26 @@ void __dump_page_owner(struct page *page) mt = gfpflags_to_migratetype(gfp_mask); if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { - pr_alert("page_owner info is not active (free page?)\n"); + pr_alert("page_owner info is not present (never set?)\n"); return; } + if (test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags)) + pr_alert("page_owner tracks the page as allocated\n"); + else + pr_alert("page_owner tracks the page as freed\n"); + + pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n", + page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask); + handle = READ_ONCE(page_owner->handle); if (!handle) { - pr_alert("page_owner info is not active (free page?)\n"); - return; + pr_alert("page_owner allocation stack trace missing\n"); + } else { + nr_entries = stack_depot_fetch(handle, &entries); + stack_trace_print(entries, nr_entries, 0); } - nr_entries = stack_depot_fetch(handle, &entries); - pr_alert("page allocated via order %u, migratetype %s, gfp_mask %#x(%pGg)\n", - page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask); - stack_trace_print(entries, nr_entries, 0); - if (page_owner->last_migrate_reason != -1) pr_alert("page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); @@ -489,6 +496,13 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) continue; + /* + * Although we do have the info about past allocation of free + * pages, it's not relevant for current memory usage. + */ + if (!test_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags)) + continue; + page_owner = get_page_owner(page_ext); /* -- 2.22.0