Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754431AbaLJL73 (ORCPT ); Wed, 10 Dec 2014 06:59:29 -0500 Received: from mail-lb0-f171.google.com ([209.85.217.171]:63030 "EHLO mail-lb0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751699AbaLJL72 (ORCPT ); Wed, 10 Dec 2014 06:59:28 -0500 MIME-Version: 1.0 In-Reply-To: <54882533.6080901@nod.at> References: <20141210104624.GB32280@tucsk.suse.de> <54882533.6080901@nod.at> Date: Wed, 10 Dec 2014 12:59:25 +0100 X-Google-Sender-Auth: d8VS04GsBoUYiIfUgRx0txcATVk Message-ID: Subject: Re: [BUG] uml panics with "Segfault with no mm" in v3.19-rc From: Geert Uytterhoeven To: Richard Weinberger Cc: Miklos Szeredi , Ley Foon Tan , Arnd Bergmann , "linux-kernel@vger.kernel.org" , Daniel Walter , user-mode-linux-devel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 10, 2014 at 11:49 AM, Richard Weinberger wrote: > Am 10.12.2014 um 11:46 schrieb Miklos Szeredi: >> The guilty commit is: >> >> 00f634bc522d "asm-generic: add generic futex for !CONFIG_SMP" > > Thanks a lot Miklos! > Your bisecting faster than I do. > > Let's dig into the issue! Do you need "select HAVE_FUTEX_CMPXCHG if FUTEX"? Cfr. commit e571c58f313d35c5 ("m68k: Skip futex_atomic_cmpxchg_inatomic() test") and commit 03b8c7b623c80af2 ("futex: Allow architectures to skip futex_atomic_cmpxchg_inatomic() test"). BTW, I still think the real problem is the wrong address space, cfr. "[PATCH/RFC] futex: Switch to USER_DS for futex test" (http://www.spinics.net/lists/linux-m68k/msg06597.html), so you may also want to try that. However, that caused problems on s390, as it ran too early: http://permalink.gmane.org/gmane.linux.kernel.next/30165 >> And the backtrace: >> >> #0 0x00007ffff7866457 in kill () from /lib64/libc.so.6 >> #1 0x000000006002a454 in uml_abort () at arch/um/os-Linux/util.c:93 >> #2 0x000000006002a7e5 in os_dump_core () at arch/um/os-Linux/util.c:148 >> #3 0x000000006001b48a in panic_exit (self=, unused1=, unused2=) at arch/um/kernel/um_arch.c:240 >> #4 0x000000006004e4df in notifier_call_chain (nl=, val=6, v=0xffffffff, nr_to_call=-1, nr_calls=0x0) at kernel/notifier.c:93 >> #5 0x000000006004e558 in __atomic_notifier_call_chain (nr_calls=, nr_to_call=, v=, val=, nh=) at kernel/notifier.c:183 >> #6 atomic_notifier_call_chain (nh=, val=, v=) at kernel/notifier.c:193 >> #7 0x0000000060238570 in panic (fmt=) at kernel/panic.c:133 >> #8 0x000000006001ad91 in segv (fi=..., ip=1610803493, is_user=, regs=0x602c1840 ) at arch/um/kernel/trap.c:218 >> #9 0x000000006001b0f8 in segv_handler (sig=, unused_si=, regs=) at arch/um/kernel/trap.c:191 >> #10 0x0000000060029238 in sig_handler_common (sig=11, si=0x602c1d30 , mc=) at arch/um/os-Linux/signal.c:44 >> #11 0x0000000060029304 in sig_handler (sig=, si=, mc=) at arch/um/os-Linux/signal.c:231 >> #12 0x0000000060028dfd in hard_handler (sig=, si=0x6, p=) at arch/um/os-Linux/signal.c:165 >> #13 >> #14 memcpy () at arch/x86/um/../lib/memcpy_64.S:160 >> #15 0x000000006001c13d in copy_from_user (to=0x61c49e28, from=, n=) at arch/um/kernel/skas/uaccess.c:145 >> #16 0x0000000060072618 in futex_atomic_cmpxchg_inatomic (newval=, oldval=, uaddr=, uval=) at include/asm-generic/futex.h:109 >> #17 cmpxchg_futex_value_locked (curval=0x61c49e28, uaddr=0x0, uval=, newval=) at kernel/futex.c:596 >> #18 0x0000000060008b70 in futex_detect_cmpxchg () at kernel/futex.c:3020 >> #19 futex_init () at kernel/futex.c:3043 >> #20 0x00000000600166ba in do_one_initcall (fn=0x60008adf ) at init/main.c:791 Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- 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/