From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755211Ab0EZTTR (ORCPT ); Wed, 26 May 2010 15:19:17 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:44363 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752721Ab0EZTTP (ORCPT ); Wed, 26 May 2010 15:19:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:reply-to:to:subject:date:user-agent:cc:references:in-reply-to :mime-version:content-type:content-transfer-encoding:message-id; b=QD58xbgCUuJYrZEXlACDiLWFsOHW7tBu3wF8cL3vTXt4DBBxFEWe9aAmb8vMkMLDLg /gmyquNW7f8oV5e4Ry9dpVBGn1Yhymsuqgrgi8eaZqILHI0W8vI0Cf/6JTazp2fIaufM MD1aQOkTCTNtHfEcMPlLt6vHGV21CPSXBvETo= From: Maciej Rutecki Reply-To: maciej.rutecki@gmail.com To: Parag Warudkar Subject: Re: UML broken for CONFIG_SLAB Date: Wed, 26 May 2010 21:19:10 +0200 User-Agent: KMail/1.12.4 (Linux/2.6.34; KDE/4.3.4; i686; ; ) Cc: linux-kernel@vger.kernel.org References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201005262119.10600.maciej.rutecki@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I created a Bugzilla entry at https://bugzilla.kernel.org/show_bug.cgi?id=16054 for your bug report, please add your address to the CC list in there, thanks! On niedziela, 23 maja 2010 o 23:40:04 Parag Warudkar wrote: > UML seems to be badly broken 2.6.34 onwards - leading to random segfaults. > > Reading symbols from /home/parag/devel/kernel/linux-2.6-um/linux...done. > (gdb) r > Starting program: /home/parag/devel/kernel/linux-2.6-um/linux > Checking that ptrace can change system call numbers...OK > Checking syscall emulation patch for ptrace...OK > Checking advanced syscall emulation patch for ptrace...OK > Checking for tmpfs mount on /dev/shm...OK > Checking PROT_EXEC mmap in /dev/shm/...OK > Checking for the skas3 patch in the host: > - /proc/mm...not found: No such file or directory > - PTRACE_FAULTINFO...not found > - PTRACE_LDT...not found > UML running in SKAS0 mode > Core dump limits : > soft - 0 > hard - NONE > > Program received signal SIGSEGV, Segmentation fault. > 0x000000006007823f in alloc_kmemlist (cachep=0x61c00f40, limit= optimized out>, batchcount=, shared= out>, gfp=208) at mm/slab.c:3861 > 3861 l3->free_limit = (1 + nr_cpus_node(node)) * > (gdb) > > (gdb) bt > #0 0x000000006007823f in alloc_kmemlist (cachep=0x61c00f40, limit= optimized out>, batchcount=, shared= out>, gfp=208) at mm/slab.c:3861 > #1 do_tune_cpucache (cachep=0x61c00f40, limit=, > batchcount=, shared=, gfp=208) > at mm/slab.c:3943 > #2 0x00000000600783be in enable_cpucache (cachep=0x61c00f40, > gfp=1639983680) at mm/slab.c:3993 > #3 0x000000006016e43d in setup_cpu_cache (cachep=0x61c00f40, gfp=208) at > mm/slab.c:2017 > #4 0x0000000060078797 in kmem_cache_create (name=0x601c80b6 > "idr_layer_cache", size=, align= out>, flags=262144, ctor=) > at mm/slab.c:2351 > #5 0x000000006000982c in idr_init_cache () at lib/idr.c:676 > #6 0x00000000600015df in start_kernel () at init/main.c:658 > > This one I tried to debug and something weird seems to be going on - > > mm/slab.c:3849 does a l3 = kmalloc_node(...), which *seems* to be > returning NULL but the check on next line - if (!l3) doesn't seem to be > succeeding. > > Finally it seems to happily dereference l3 (0x40 offsets etc.) up until > dereferencing free_limit at which point it explodes. > > A very few times it goes a little further and explodes at > > fsck from util-linux-ng 2.16 > ROOT: clean, 18550/65536 files, 106443/262144 blocks > > Program received signal SIGSEGV, Segmentation fault. > 0x00000000600effb7 in cfq_close_cooperator (cfqd=0x7fcbe000, > cur_cfqq=0x7ff81bb0) at block/cfq-iosched.c:1801 > 1801 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) > (gdb) p cfqq > $1 = (struct cfq_queue *) 0x0 > (gdb) p cur_cfqq > $2 = (struct cfq_queue *) 0x7ff81bb0 > (gdb) > > This is with CONFIG_SLAB=y. > > Parag > -- > 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/ > -- Maciej Rutecki http://www.maciek.unixy.pl