From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755321AbdAKTKm (ORCPT ); Wed, 11 Jan 2017 14:10:42 -0500 Received: from mx2.suse.de ([195.135.220.15]:54075 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751531AbdAKTKk (ORCPT ); Wed, 11 Jan 2017 14:10:40 -0500 Date: Wed, 11 Jan 2017 20:10:36 +0100 From: "Luis R. Rodriguez" To: "Luis R. Rodriguez" Cc: shuah@kernel.org, jeyu@redhat.com, rusty@rustcorp.com.au, ebiederm@xmission.com, dmitry.torokhov@gmail.com, acme@redhat.com, corbet@lwn.net, martin.wilck@suse.com, mmarek@suse.com, pmladek@suse.com, hare@suse.com, rwright@hpe.com, jeffm@suse.com, DSterba@suse.com, fdmanana@suse.com, neilb@suse.com, rgoldwyn@suse.com, subashab@codeaurora.org, xypron.glpk@gmx.de, keescook@chromium.org, atomlin@redhat.com, mbenes@suse.cz, paulmck@linux.vnet.ibm.com, dan.j.williams@intel.com, jpoimboe@redhat.com, davem@davemloft.net, mingo@redhat.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 00/10] kmod: stress test driver, few fixes and enhancements Message-ID: <20170111191036.GP13946@wotan.suse.de> References: <20161208184801.1689-1-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161208184801.1689-1-mcgrof@kernel.org> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 08, 2016 at 10:47:51AM -0800, Luis R. Rodriguez wrote: > Upon running into an old kmod v19 issue with mount (get_fs_type()) a few of us > hunted for the cause of the issue. Although the issue ended up being a > userspace issue, a stress test driver was written to help reproduce the issue, > and along the way a few other fixes and sanity checks were implemented. > > I've taken the time to generalize the stress test driver as a kselftest driver > with a 9 test cases. The last two test cases reveal an existing issue which > is not yet addressed upstream, even if you have kmod v19 present. A fix is > proposed in the last patch. Orignally we had discarded this patch as too > complex due to the alias handling, but upon further analysis of test cases > and memory pressure issues, it seems worth considering. Other than the > last patch I don't think much of the other patches are controversial, but > sending as RFC first just in case. > > If its not clear, an end goal here is to make module loading a bit more > deterministic with stronger sanity checks and stress tests. Please note, > the stress test diver requires 4 GiB of RAM to run all tests without running > out of memory. A lot of this has to do with the memory requirements needed > for a dynamic test for multiple threads, but note that the final memory > pressure and OOMs actually don't come from this allocation, but instead > from many finit_module() calls, this consumes quite a bit of memory, specially > if you have a lot of dependencies which also need to be loaded prior to > your needed module -- as is the case for filesystem drivers. > > These patches are available on my linux-next git-tree on my branch > 20161208-kmod-test-driver-try2 [0], which is based on linux-next tag > next-20161208. Patches are also available based on v4.9-rc8 [1] for > those looking for a bit more stable tree given x86_64 on linux-next is > hosed at the moment. > > Since kmod.c doesn't seem to get much love, and since I've been digging > quite a bit into it for other users (firmware) I suppose I could volunteer > myself to maintain this code as well, unless there are oppositions to this. > > [0] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linux-next.git/log/?h=20161208-kmod-test-driver-try2 > [1] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linux.git/log/?h=20161208-kmod-test-driver > > Luis R. Rodriguez (10): > kmod: add test driver to stress test the module loader > module: fix memory leak on early load_module() failures > kmod: add dynamic max concurrent thread count > kmod: provide wrappers for kmod_concurrent inc/dec > kmod: return -EBUSY if modprobe limit is reached > kmod: provide sanity check on kmod_concurrent access > kmod: use simplified rate limit printk > sysctl: add support for unsigned int properly > kmod: add helpers for getting kmod count and limit > kmod: add a sanity check on module loading > A lot of good discussions have come up form this, and so also a few more patches. I'm going to split up the work into changes which make sense now and leave debug work for a follow up later. Luis