From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f43.google.com (mail-wg0-f43.google.com [74.125.82.43]) by kanga.kvack.org (Postfix) with ESMTP id 242136B00D7 for ; Thu, 8 May 2014 05:27:31 -0400 (EDT) Received: by mail-wg0-f43.google.com with SMTP id l18so2176655wgh.2 for ; Thu, 08 May 2014 02:27:30 -0700 (PDT) Received: from collaborate-mta1.arm.com (fw-tnat.austin.arm.com. [217.140.110.23]) by mx.google.com with ESMTP id i4si156537wjf.190.2014.05.08.02.27.29 for ; Thu, 08 May 2014 02:27:29 -0700 (PDT) Date: Thu, 8 May 2014 10:26:46 +0100 From: Catalin Marinas Subject: Re: [BUG] kmemleak on __radix_tree_preload Message-ID: <20140508092646.GA17349@arm.com> References: <1398390340.4283.36.camel@kjgkr> <20140501170610.GB28745@arm.com> <20140501184112.GH23420@cmpxchg.org> <1399431488.13268.29.camel@kjgkr> <20140507113928.GB17253@arm.com> <1399540611.13268.45.camel@kjgkr> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1399540611.13268.45.camel@kjgkr> Sender: owner-linux-mm@kvack.org List-ID: To: Jaegeuk Kim Cc: Johannes Weiner , "Linux Kernel, Mailing List" , "linux-mm@kvack.org" On Thu, May 08, 2014 at 06:16:51PM +0900, Jaegeuk Kim wrote: > 2014-05-07 (i??), 12:39 +0100, Catalin Marinas: > > On Wed, May 07, 2014 at 03:58:08AM +0100, Jaegeuk Kim wrote: > > > unreferenced object 0xffff880004226da0 (size 576): > > > comm "fsstress", pid 14590, jiffies 4295191259 (age 706.308s) > > > hex dump (first 32 bytes): > > > 01 00 00 00 81 ff ff ff 00 00 00 00 00 00 00 00 ................ > > > 50 89 34 81 ff ff ff ff b8 6d 22 04 00 88 ff ff P.4......m"..... > > > backtrace: > > > [] kmemleak_update_trace+0x58/0x80 > > > [] radix_tree_node_alloc+0x77/0xa0 > > > [] __radix_tree_create+0x1d8/0x230 > > > [] __add_to_page_cache_locked+0x9c/0x1b0 > > > [] add_to_page_cache_lru+0x28/0x80 > > > [] grab_cache_page_write_begin+0x98/0xf0 > > > [] f2fs_write_begin+0xb4/0x3c0 [f2fs] > > > [] generic_perform_write+0xc7/0x1c0 > > > [] __generic_file_aio_write+0x1cd/0x3f0 > > > [] generic_file_aio_write+0x5e/0xe0 > > > [] do_sync_write+0x5a/0x90 > > > [] vfs_write+0xc2/0x1d0 > > > [] SyS_write+0x4f/0xb0 > > > [] system_call_fastpath+0x16/0x1b > > > [] 0xffffffffffffffff > > > > OK, it shows that the allocation happens via add_to_page_cache_locked() > > and I guess it's page_cache_tree_insert() which calls > > __radix_tree_create() (the latter reusing the preloaded node). I'm not > > familiar enough to this code (radix-tree.c and filemap.c) to tell where > > the node should have been freed, who keeps track of it. > > > > At a quick look at the hex dump (assuming that the above leak is struct > > radix_tree_node): > > > > .path = 1 > > .count = -0x7f (or 0xffffff81 as unsigned int) > > union { > > { > > .parent = NULL > > .private_data = 0xffffffff81348950 > > } > > { > > .rcu_head.next = NULL > > .rcu_head.func = 0xffffffff81348950 > > } > > } > > > > The count is a bit suspicious. > > > > From the union, it looks most likely like rcu_head information. Is > > radix_tree_node_rcu_free() function at the above rcu_head.func? Thanks for the config. Could you please confirm that 0xffffffff81348950 address corresponds to the radix_tree_node_rcu_free() function in your System.map (or something else)? > > Also, if you run echo scan > /sys/kernel/debug/kmemleak a few times, do > > any of the above leaks disappear (in case the above are some transient > > rcu freeing reports; normally this shouldn't happen as the objects are > > still referred but I'll look at the relevant code once I have your > > .config). > > Once I run the echo, the leaks are still remained. OK, so they aren't just transient. Thanks. -- Catalin -- 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