Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751318AbdIJSjm (ORCPT ); Sun, 10 Sep 2017 14:39:42 -0400 Received: from mx3.wp.pl ([212.77.101.9]:26190 "EHLO mx3.wp.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750730AbdIJSjl (ORCPT ); Sun, 10 Sep 2017 14:39:41 -0400 Date: Sun, 10 Sep 2017 20:39:37 +0200 From: Jakub Kicinski To: Dmitry Torokhov Cc: LKML , Greg Kroah-Hartman Subject: Re: [bisected] Re: Module removal-related regression? Message-ID: <20170910203937.17d4603a@cakuba.netronome.com> In-Reply-To: <8D38F5B5-C5EA-4436-91CB-B302A42A78F0@gmail.com> References: <20170909194121.39cd9f56@cakuba.netronome.com> <20170909212732.5bc98775@cakuba.netronome.com> <20170909221726.241c29f6@cakuba.netronome.com> <20170910000338.093aa04e@cakuba.netronome.com> <20170910162111.GA17387@dtor-ws> <20170910200010.4ad7a032@cakuba.netronome.com> <8D38F5B5-C5EA-4436-91CB-B302A42A78F0@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-WP-MailID: 4524bc9ace1fe531884aa2614acff9f5 X-WP-AV: skaner antywirusowy Poczty Wirtualnej Polski X-WP-SPAM: NO 000000A [sTN0] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5134 Lines: 130 On Sun, 10 Sep 2017 11:12:17 -0700, Dmitry Torokhov wrote: > On September 10, 2017 11:00:10 AM PDT, Jakub Kicinski wrote: > >On Sun, 10 Sep 2017 09:21:11 -0700, Dmitry Torokhov wrote: > >> On Sun, Sep 10, 2017 at 12:03:38AM +0200, Jakub Kicinski wrote: > >> > On Sat, 09 Sep 2017 13:59:25 -0700, Dmitry Torokhov wrote: > >> > > On September 9, 2017 1:17:26 PM PDT, Jakub Kicinski > > wrote: > >> > > >On Sat, 9 Sep 2017 12:55:51 -0700, Dmitry Torokhov wrote: > >> > > >> On Sat, Sep 9, 2017 at 12:27 PM, Jakub Kicinski > > > >> > > >wrote: > >> > > >> > On Sat, 9 Sep 2017 19:41:21 +0200, Jakub Kicinski wrote: > > > >> > > >> >> Hi! > >> > > >> >> > >> > > >> >> I'm having trouble with modules on linux/master. rmmod > >succeeds > >> > > >but the > >> > > >> >> module is still loaded and the refcount goes to 1: > >> > > >> >> > >> > > >> >> #rmmod nfp; insmod ./src/nfp.ko nfp_pf_netdev=0 ; \ > >> > > >> >> /opt/netronome/bin/nfp-hwinfo -n 2 assembly.partno \ > >> > > >> >> lsmod | grep nfp; \ > >> > > >> >> rmmod nfp; \ > >> > > >> >> lsmod | grep nfp > >> > > >> >> nfp 249856 0 > >> > > >> >> nfp 200704 1 > >> > > >> >> > >> > > >> >> If I rmmod again the module will be actually unloaded. The > >user > >> > > >space > >> > > >> >> is mostly Ubuntu 14.04. Has anyone seen this? I'm trying > >to > >> > > >bisect > >> > > >> >> now... > >> > > >> > > >> > > >> > Got 'em! > >> > > >> > > >> > > >> > commit 1455cf8dbfd06aa7651dcfccbadb7a093944ca65 (HEAD, > >> > > >refs/bisect/bad) > >> > > >> > Author: Dmitry Torokhov > >> > > >> > Date: Wed Jul 19 17:24:30 2017 -0700 > >> > > >> > > >> > > >> > driver core: emit uevents when device is bound to a > >driver > >> > > >> > >> > > >> Does it happen with all modules or only nfp one? > >> > > >> > >> > > >> It seems to work here: > >> > > >> > >> > > >> dtor@dtor-glaptop3:~ $ lsmod | grep psmouse > >> > > >> psmouse 135168 0 > >> > > >> dtor@dtor-glaptop3:~ $ sudo rmmod psmouse > >> > > >> dtor@dtor-glaptop3:~ $ lsmod | grep psmouse > >> > > >> dtor@dtor-glaptop3:~ $ sudo modprobe psmouse > >> > > > > >> > > >It looks like the driver is actually reloaded. The driver used > >to > >> > > >return EPROBE_DEFER, but I think it doesn't any more (rebuilding > >the > >> > > >kernel to test that right now). > >> > > > > >> > > >Could the uevent on unbind tickle Ubuntu 14.04's udev or somehow > >> > > >else cause the driver to be loaded again? > >> > > > >> > > It depends on how silly the udev rules are, but yes, this can > >definitely happen. > >> > > >> > I confirmed the driver doesn't use EPROBE_DEFER any more: > >> > > >> > $ grep -nrI EPROBE_DEFER drivers/net/ethernet/netronome/ > >> > $ > >> > >> Not sure why you bring the deferrals here, they have nothing to do > >with > >> module removal. Also, deferrals are rarely issued by the leaf driver, > >and > >> more often by providers of resources (GPIO, regulator, interrupt, > >etc). > > > >Yes, it's unusual, but this driver used to do it. Which is exactly why > >I brought it up. Turns out it was irrelevant :) > > > >> > I tested without any udev rules in /etc/udev/, just the standard > >distro > >> > ones. Same thing. > >> > >> Right, so this is the default udev rule: > >> > >> /lib/udev/rules.d/80-drivers.rules: > >> > >> # do not edit this file, it will be overwritten on update > >> > >> ACTION=="remove", GOTO="drivers_end" > >> > >> ENV{MODALIAS}=="?*", RUN{builtin}="kmod load $env{MODALIAS}" > >> SUBSYSTEM=="tifm", ENV{TIFM_CARD_TYPE}=="SD", RUN{builtin}="kmod load > >tifm_sd" > >> SUBSYSTEM=="tifm", ENV{TIFM_CARD_TYPE}=="MS", RUN{builtin}="kmod load > >tifm_ms" > >> SUBSYSTEM=="memstick", RUN{builtin}="kmod load ms_block mspro_block" > >> SUBSYSTEM=="i2o", RUN{builtin}="kmod load i2o_block" > >> SUBSYSTEM=="module", KERNEL=="parport_pc", RUN{builtin}="kmod load > >ppdev" > >> SUBSYSTEM=="serio", ENV{MODALIAS}=="?*", RUN{builtin}="kmod load > >$env{MODALIAS}" > >> SUBSYSTEM=="graphics", RUN{builtin}="kmod load fbcon" > >> KERNEL=="mtd*ro", ENV{MTD_FTL}=="smartmedia", RUN{builtin}="kmod load > >sm_ftl" > >> > >> LABEL="drivers_end" > >> > >> So udev (and systemd) want to load kernel module on any action > >besides > >> device removal. Shortsighted decision I'd say. I'll send a patch to > >> systemd, in the mean time you can simply adjust your local rule to > >read > >> > >> ACTION!="add", GOTO="drivers_end" > > > >Mm. That is a silly thing. You will break a lot of setups, though. > > I think the priority it to have module loading working properly, and > for most users once module is loaded it stays loaded. Unloading is > mostly for developers. > > Luckily newer systemd versions drop events they do not recognize, so > exposure is even smaller. Could you point me to where that's done?