Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753967AbZDPVhI (ORCPT ); Thu, 16 Apr 2009 17:37:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753349AbZDPVgz (ORCPT ); Thu, 16 Apr 2009 17:36:55 -0400 Received: from mail-fx0-f158.google.com ([209.85.220.158]:49043 "EHLO mail-fx0-f158.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753179AbZDPVgy convert rfc822-to-8bit (ORCPT ); Thu, 16 Apr 2009 17:36:54 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=kPive23m7bmhabzrlqN68EbMdtLUqJyU0nzdUAlVQ4vu/L6KvJ31xPeHds2Nm7D5XK RWo04geEOijFcL7PE74ZjLGbZpL8fM2DoZdAt2dkP66uHasZnokXT6VLZCU87QnWW9BQ upYa5SOEzuYQXuUxnMMa7ECtwRApYiccQ+4SI= MIME-Version: 1.0 In-Reply-To: <49E7A377.3000901@linux.intel.com> References: <20090410231245.GF6719@linux.vnet.ibm.com> <200904150328.n3F3S0F9083222@www262.sakura.ne.jp> <200904160046.n3G0ki9o028612@www262.sakura.ne.jp> <200904160535.n3G5ZBIE006724@www262.sakura.ne.jp> <20090416212436.GA31113@suse.de> <49E7A377.3000901@linux.intel.com> Date: Thu, 16 Apr 2009 22:36:52 +0100 Message-ID: <87a5b0800904161436u2226daf4y7bbaf99c4ac85f1a@mail.gmail.com> Subject: Re: Please revert kobject_uevent UMH_NO_WAIT From: Will Newton To: Arjan van de Ven Cc: Greg KH , Hugh Dickins , Linus Torvalds , Tetsuo Handa , alan@lxorguk.ukuu.org.uk, viro@zeniv.linux.org.uk, jmorris@namei.org, akpm@linux-foundation.org, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2171 Lines: 54 On Thu, Apr 16, 2009 at 10:30 PM, Arjan van de Ven wrote: > Greg KH wrote: >> >> On Thu, Apr 16, 2009 at 09:55:29PM +0100, Hugh Dickins wrote: >>> >>> Please revert commit f520360d93cdc37de5d972dac4bf3bdef6a7f6a7 >>> "kobject: don't block for each kobject_uevent". >>> >>> Tetsuo Handa, running a kernel with CONFIG_DEBUG_PAGEALLOC=y >>> and CONFIG_UEVENT_HELPER_PATH=/sbin/hotplug, has been hitting RCU >>> detected CPU stalls: it's been spinning in the loop where do_execve() >>> counts up the args (but why wasn't fixup_exception working? dunno). >>> >>> The recent change, switching kobject_uevent_env() from UMH_WAIT_EXEC >>> to UMH_NO_WAIT, is broken: the exec uses args on the local stack here, >>> and an env which is kfreed as soon as call_usermodehelper() returns. >>> It very much needs to wait for the exec to be done. >>> >>> Or keep the UMH_NO_WAIT, and complicate the code to allocate and free >>> these resources correctly? ?No, as GregKH pointed out when making the >>> commit, CONFIG_UEVENT_HELPER_PATH="" is a much better optimization - >>> though some distros are still saying /sbin/hotplug in their .config, >>> yet with no such binary in their initrd or their root. >>> >>> Or... >>> >>> [PATCH] revert kobject_uevent UMH_NO_WAIT >>> >>> Reported-by: Tetsuo Handa >>> Signed-off-by: Hugh Dickins >> >> Acked-by: Greg Kroah-Hartman > > Acked-by: Arjan van de Ven > as well > > not worth the hassle if this breaks too much Acked-by: Will Newton It's causing crashes for me too (reported 10 days ago). > -- > 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/ > -- 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/