From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f43.google.com (mail-wm0-f43.google.com [74.125.82.43]) by kanga.kvack.org (Postfix) with ESMTP id 48A886B0255 for ; Wed, 25 Nov 2015 09:58:56 -0500 (EST) Received: by wmec201 with SMTP id c201so73668874wme.1 for ; Wed, 25 Nov 2015 06:58:55 -0800 (PST) Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com. [74.125.82.52]) by mx.google.com with ESMTPS id fk13si20309592wjc.15.2015.11.25.06.58.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Nov 2015 06:58:55 -0800 (PST) Received: by wmuu63 with SMTP id u63so141412759wmu.0 for ; Wed, 25 Nov 2015 06:58:55 -0800 (PST) Date: Wed, 25 Nov 2015 15:58:54 +0100 From: Michal Hocko Subject: Re: [PATCH v2 7/9] mm, page_owner: dump page owner info from dump_page() Message-ID: <20151125145853.GM27283@dhcp22.suse.cz> References: <1448368581-6923-1-git-send-email-vbabka@suse.cz> <1448368581-6923-8-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448368581-6923-8-git-send-email-vbabka@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman On Tue 24-11-15 13:36:19, Vlastimil Babka wrote: > The page_owner mechanism is useful for dealing with memory leaks. By reading > /sys/kernel/debug/page_owner one can determine the stack traces leading to > allocations of all pages, and find e.g. a buggy driver. > > This information might be also potentially useful for debugging, such as the > VM_BUG_ON_PAGE() calls to dump_page(). So let's print the stored info from > dump_page(). > > Example output: > > page:ffffea0002868a00 count:1 mapcount:0 mapping:ffff8800bba8e958 index:0x63a22c > flags: 0x1fffff80000060(lru|active) > page dumped because: VM_BUG_ON_PAGE(1) > page->mem_cgroup:ffff880138efdc00 > page allocated via order 0, migratetype Movable, gfp_mask 0x2420848(GFP_NOFS|GFP_NOFAIL|GFP_HARDWALL|GFP_MOVABLE) > [] __alloc_pages_nodemask+0x15a/0xa30 > [] alloc_pages_current+0x88/0x120 > [] __page_cache_alloc+0xe6/0x120 > [] pagecache_get_page+0x56/0x200 > [] __getblk_slow+0xd2/0x2b0 > [] __getblk_gfp+0x40/0x50 > [] jbd2_journal_get_descriptor_buffer+0x3e/0x90 [jbd2] > [] jbd2_journal_commit_transaction+0x8e3/0x1870 [jbd2] > page has been migrated, last migrate reason: compaction Nice! This can be really helpful. > Signed-off-by: Vlastimil Babka Appart from a typo below, looks good to me Acked-by: Michal Hocko [...] > +void __dump_page_owner(struct page *page) > +{ > + struct page_ext *page_ext = lookup_page_ext(page); > + struct stack_trace trace = { > + .nr_entries = page_ext->nr_entries, > + .entries = &page_ext->trace_entries[0], > + }; > + gfp_t gfp_mask = page_ext->gfp_mask; > + int 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"); > + return; > + } > + ; Typo? > + pr_alert("page allocated via order %u, migratetype %s, gfp_mask 0x%x", > + page_ext->order, migratetype_names[mt], gfp_mask); > + dump_gfpflag_names(gfp_mask); > + print_stack_trace(&trace, 0); > + > + if (page_ext->last_migrate_reason != -1) > + pr_alert("page has been migrated, last migrate reason: %s\n", > + migrate_reason_names[page_ext->last_migrate_reason]); > +} > + > static ssize_t > read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) > { > -- > 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