Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754410AbZDPVan (ORCPT ); Thu, 16 Apr 2009 17:30:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752092AbZDPVad (ORCPT ); Thu, 16 Apr 2009 17:30:33 -0400 Received: from mga10.intel.com ([192.55.52.92]:44982 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750992AbZDPVad (ORCPT ); Thu, 16 Apr 2009 17:30:33 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,200,1239001200"; d="scan'208";a="448612108" Message-ID: <49E7A377.3000901@linux.intel.com> Date: Thu, 16 Apr 2009 14:30:31 -0700 From: Arjan van de Ven User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 To: Greg KH CC: 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 Subject: Re: Please revert kobject_uevent UMH_NO_WAIT References: <20090410231245.GF6719@linux.vnet.ibm.com> <20090410233919.GS26366@ZenIV.linux.org.uk> <200904130048.n3D0mw1f077050@www262.sakura.ne.jp> <200904150328.n3F3S0F9083222@www262.sakura.ne.jp> <200904160046.n3G0ki9o028612@www262.sakura.ne.jp> <200904160535.n3G5ZBIE006724@www262.sakura.ne.jp> <20090416212436.GA31113@suse.de> In-Reply-To: <20090416212436.GA31113@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1683 Lines: 39 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 -- 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/