Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030735AbbKDTlK (ORCPT ); Wed, 4 Nov 2015 14:41:10 -0500 Received: from mail-wi0-f170.google.com ([209.85.212.170]:38334 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030439AbbKDTlH (ORCPT ); Wed, 4 Nov 2015 14:41:07 -0500 Date: Wed, 4 Nov 2015 21:41:04 +0200 From: "Kirill A. Shutemov" To: Vlastimil Babka Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Minchan Kim , Sasha Levin , "Kirill A. Shutemov" , Mel Gorman Subject: Re: [PATCH 5/5] mm, page_owner: dump page owner info from dump_page() Message-ID: <20151104194104.GB13303@node.shutemov.name> References: <1446649261-27122-1-git-send-email-vbabka@suse.cz> <1446649261-27122-6-git-send-email-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446649261-27122-6-git-send-email-vbabka@suse.cz> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5517 Lines: 144 On Wed, Nov 04, 2015 at 04:01:01PM +0100, 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: > > [ 199.188777] page:ffffea0002900540 count:2 mapcount:0 mapping:ffff880131993e18 index:0x34e > [ 199.202832] flags: 0x1fffff80020048(uptodate|active|mappedtodisk) > [ 199.207048] page dumped because: VM_BUG_ON_PAGE(1) > [ 199.207048] page->mem_cgroup:ffff880138efdc00 > [ 199.207050] page allocated via order 0, mask 0x213da, migratetype 2, trace: Can we decode gfp_mask and migratetype into something more human readable? > [ 199.207050] [] __alloc_pages_nodemask+0x175/0x900 > [ 199.207057] [] alloc_pages_current+0x91/0x100 > [ 199.207061] [] __page_cache_alloc+0xb1/0xf0 > [ 199.207066] [] __do_page_cache_readahead+0xdb/0x200 > [ 199.207067] [] ondemand_readahead+0x145/0x270 > [ 199.207069] [] page_cache_async_readahead+0x6c/0x70 > [ 199.207070] [] generic_file_read_iter+0x378/0x590 > [ 199.207074] [] __vfs_read+0xa7/0xd0 > [ 199.207074] page has been migrated, last migrate reason: 0 Same here. > > Signed-off-by: Vlastimil Babka > --- > include/linux/page_owner.h | 9 +++++++++ > mm/debug.c | 2 ++ > mm/page_owner.c | 18 ++++++++++++++++++ > 3 files changed, 29 insertions(+) > > diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h > index 555893b..46f1b93 100644 > --- a/include/linux/page_owner.h > +++ b/include/linux/page_owner.h > @@ -13,6 +13,7 @@ extern void __set_page_owner(struct page *page, > extern gfp_t __get_page_owner_gfp(struct page *page); > extern void __copy_page_owner(struct page *oldpage, struct page *newpage); > extern void __set_page_owner_migrate_reason(struct page *page, int reason); > +extern void __dump_page_owner(struct page *page); > > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -44,6 +45,11 @@ static inline void set_page_owner_migrate_reason(struct page *page, int reason) > if (static_branch_unlikely(&page_owner_inited)) > __set_page_owner_migrate_reason(page, reason); > } > +static inline void dump_page_owner(struct page *page) > +{ > + if (static_branch_unlikely(&page_owner_inited)) > + __dump_page_owner(page); > +} > #else > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -62,5 +68,8 @@ static inline void copy_page_owner(struct page *oldpage, struct page *newpage) > static inline void set_page_owner_migrate_reason(struct page *page, int reason) > { > } > +static inline void dump_page_owner(struct page *page) > +{ > +} > #endif /* CONFIG_PAGE_OWNER */ > #endif /* __LINUX_PAGE_OWNER_H */ > diff --git a/mm/debug.c b/mm/debug.c > index 8362765..93373d1 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > > static const struct trace_print_flags pageflag_names[] = { > {1UL << PG_locked, "locked" }, > @@ -98,6 +99,7 @@ void dump_page_badflags(struct page *page, const char *reason, > if (page->mem_cgroup) > pr_alert("page->mem_cgroup:%p\n", page->mem_cgroup); > #endif > + dump_page_owner(page); I tend to put dump_page() into random places during debug. Dumping page owner for all dump_page() cases can be too verbose. Can we introduce dump_page_verbose() which would do usual dump_page() plus dump_page_owner()? > } > > void dump_page(struct page *page, const char *reason) > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 388898f..d7e0aaf 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -183,6 +183,24 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, > return -ENOMEM; > } > > +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], > + }; > + > + pr_alert("page allocated via order %u, mask 0x%x, migratetype %d, trace:\n", > + page_ext->order, page_ext->gfp_mask, > + gfpflags_to_migratetype(page_ext->gfp_mask)); > + print_stack_trace(&trace, 0); > + > + if (page_ext->last_migrate_reason != -1) > + pr_alert("page has been migrated, last migrate reason: %d\n", > + page_ext->last_migrate_reason); > +} > + > static ssize_t > read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) > { > -- > 2.6.2 > > -- > 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/ -- Kirill A. Shutemov -- 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/