From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756729Ab1KVJoz (ORCPT ); Tue, 22 Nov 2011 04:44:55 -0500 Received: from mail-yw0-f46.google.com ([209.85.213.46]:40362 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750766Ab1KVJox (ORCPT ); Tue, 22 Nov 2011 04:44:53 -0500 Message-ID: <1321954729.2474.4.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Subject: Re: WARNING: at mm/slub.c:3357, kernel BUG at mm/slub.c:3413 From: Eric Dumazet To: Markus Trippelsdorf Cc: Christoph Lameter , Christian Kujau , Benjamin Herrenschmidt , "Alex,Shi" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Pekka Enberg , Matt Mackall , "netdev@vger.kernel.org" , Tejun Heo Date: Tue, 22 Nov 2011 10:38:49 +0100 In-Reply-To: <20111122084513.GA1688@x4.trippels.de> References: <20111121161036.GA1679@x4.trippels.de> <1321894353.10470.19.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <1321895706.10470.21.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <20111121173556.GA1673@x4.trippels.de> <1321900743.10470.31.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> <20111121185215.GA1673@x4.trippels.de> <20111121195113.GA1678@x4.trippels.de> <1321907275.13860.12.camel@pasglop> <20111122084513.GA1688@x4.trippels.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.1- Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le mardi 22 novembre 2011 à 09:45 +0100, Markus Trippelsdorf a écrit : > I sometimes see the following pattern. Is this a false positive? > > > ============================================================================= > BUG anon_vma: Redzone overwritten > ----------------------------------------------------------------------------- > > INFO: 0xffff88020f347c80-0xffff88020f347c87. First byte 0xbb instead of 0xcc > INFO: Allocated in anon_vma_fork+0x51/0x140 age=1 cpu=2 pid=1826 > __slab_alloc.constprop.70+0x1ac/0x1e8 > kmem_cache_alloc+0x12e/0x160 > anon_vma_fork+0x51/0x140 > dup_mm+0x1f2/0x4a0 > copy_process+0xd10/0xf70 > do_fork+0x100/0x2b0 > sys_clone+0x23/0x30 > stub_clone+0x13/0x20 > INFO: Freed in __put_anon_vma+0x54/0xa0 age=0 cpu=1 pid=1827 > __slab_free+0x33/0x2d0 > kmem_cache_free+0x10e/0x120 > __put_anon_vma+0x54/0xa0 > unlink_anon_vmas+0x12f/0x1c0 > free_pgtables+0x83/0xe0 > exit_mmap+0xee/0x140 > mmput+0x43/0xf0 > flush_old_exec+0x33f/0x630 > load_elf_binary+0x340/0x1960 > search_binary_handler+0x8f/0x180 > do_execve+0x2d3/0x370 > sys_execve+0x42/0x70 > stub_execve+0x6c/0xc0 > INFO: Slab 0xffffea00083cd1c0 objects=10 used=9 fp=0xffff88020f347ab8 flags=0x4000000000000081 > INFO: Object 0xffff88020f347c40 @offset=3136 fp=0xffff88020f347ab8 > > Bytes b4 ffff88020f347c30: 39 b6 fb ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a 9.......ZZZZZZZZ > Object ffff88020f347c40: 30 c9 9b 0d 02 88 ff ff 01 00 00 00 00 00 5a 5a 0.............ZZ > Object ffff88020f347c50: 50 7c 34 0f 02 88 ff ff 50 7c 34 0f 02 88 ff ff P|4.....P|4..... > Object ffff88020f347c60: 00 00 00 00 00 00 00 00 00 00 00 00 5a 5a 5a 5a ............ZZZZ > Object ffff88020f347c70: 70 7c 34 0f 02 88 ff ff 70 7c 34 0f 02 88 ff ff p|4.....p|4..... > Redzone ffff88020f347c80: bb bb bb bb bb bb bb bb ........ > Padding ffff88020f347dc0: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ > Pid: 1820, comm: slabinfo Not tainted 3.2.0-rc2-00369-gbbbc479-dirty #83 > Call Trace: > [] ? print_section+0x38/0x40 > [] print_trailer+0xe3/0x150 > [] check_bytes_and_report+0xe0/0x100 > [] check_object+0x183/0x240 > [] validate_slab_slab+0x1c0/0x230 > [] validate_store+0xa6/0x190 > [] slab_attr_store+0x1c/0x30 > [] sysfs_write_file+0xc8/0x140 > [] vfs_write+0xa3/0x160 > [] sys_write+0x45/0x90 > [] system_call_fastpath+0x16/0x1b > FIX anon_vma: Restoring 0xffff88020f347c80-0xffff88020f347c87=0xcc Wait a minute You trigger this using slabinfo looping or something ? Bug is in slabinfo then, dont use it, and see if bug triggers. Given slub is now lockless, validate_slab_slab() is probably very wrong these days.