From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F4C6C2BB54 for ; Tue, 7 Apr 2020 11:55:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 367B720731 for ; Tue, 7 Apr 2020 11:55:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="MgUm0WOp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728306AbgDGLzw (ORCPT ); Tue, 7 Apr 2020 07:55:52 -0400 Received: from mail-qk1-f196.google.com ([209.85.222.196]:40098 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728146AbgDGLzv (ORCPT ); Tue, 7 Apr 2020 07:55:51 -0400 Received: by mail-qk1-f196.google.com with SMTP id z15so1252966qki.7 for ; Tue, 07 Apr 2020 04:55:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ceAe9s5g1bpqs/xuk9UoBUiTWj0Xhc3RDSdNgpswe0Q=; b=MgUm0WOp8c8FLGB7Ig9nz5OKFLDWqyBHiLaWKxbCjl1iyEUxM/1XZNr5O+NhZHo4fe R0Z4TJCHZYXh8L+/cnbal1UBc20KEWoa0ukvwx3SVgDGMMOhhguGv0RYFu+d5DyTCIBf jHKEw9N6iCFhBkxiuxyt5R7nS9hQi5T4HbwpN5hDyOlI7PsUtPVBvNEooBibfPsXyt+K nJWpiDXZcDh8f06MQ4IXCB9B6lojiTIDGV51LtXY/UuE+bzimWeak/KA3iFWTFKX3bks //GWpDCzc5fL8Z5Y01nEBk8UUbKsTx46WlNeMjhIq1HC7P85+dHAmmuXmnPMDcmhHg+B IOIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=ceAe9s5g1bpqs/xuk9UoBUiTWj0Xhc3RDSdNgpswe0Q=; b=CFPbK5lqCb/WE47JHjaVPuj99C27JvjH61JbRUoCYnri/fSnjvgR8NM22HyZUsic2C 12nftVIRbAA3sDBNE+N7y/Swn8+8kyo7sQXQTPJU8V/Ya9LwN9h1lhHqKsiI2Ft8oFpt vIqdNQjWlSNQzqRIsu6tE7Ta/nYB7iXyFwZ0gOZT4wnBQRXc9J0qy4ZXvnkW0aRtTsVi IUuZ9rCOeZ8CKlDUKUmzETtrpLDQh+qI2pcsAYweRzHVnNqj1cVI1bC/VW5LMorm+EaU Z0xVzAYIaklBvtC2LfQGG67LT/Sth6sMANnbQB2uJ4VCwKOrKPQyinErRWhP9vbQiay+ T8Yg== X-Gm-Message-State: AGi0PuZR8SYevEuM4dlyG6Ad3mE1zoHBW5fXFPbQ/b9tQEhDeSkl+iL8 GWzCKFXso0DL4cHWdVIG+1HIYQ== X-Google-Smtp-Source: APiQypI6tyZXZJ/lR2tBYH+vI4JsVy0kISJi44Lw4iUz36y6gU16DjHD+k1n8fMNxZYuWTBREupC8w== X-Received: by 2002:a05:620a:91d:: with SMTP id v29mr1681222qkv.424.1586260549945; Tue, 07 Apr 2020 04:55:49 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-68-57-212.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.57.212]) by smtp.gmail.com with ESMTPSA id q13sm7074962qki.136.2020.04.07.04.55.49 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 07 Apr 2020 04:55:49 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jLmpY-0007fp-Nb; Tue, 07 Apr 2020 08:55:48 -0300 Date: Tue, 7 Apr 2020 08:55:48 -0300 From: Jason Gunthorpe To: Dmitry Vyukov Cc: Leon Romanovsky , syzbot , RDMA mailing list , Greg Kroah-Hartman , LKML , netdev , Rafael Wysocki , syzkaller-bugs Subject: Re: WARNING in ib_umad_kill_port Message-ID: <20200407115548.GU20941@ziepe.ca> References: <00000000000075245205a2997f68@google.com> <20200406172151.GJ80989@unreal> <20200406174440.GR20941@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Apr 07, 2020 at 11:56:30AM +0200, Dmitry Vyukov wrote: > > I'm not sure what could be done wrong here to elicit this: > > > > sysfs group 'power' not found for kobject 'umad1' > > > > ?? > > > > I've seen another similar sysfs related trigger that we couldn't > > figure out. > > > > Hard to investigate without a reproducer. > > Based on all of the sysfs-related bugs I've seen, my bet would be on > some races. E.g. one thread registers devices, while another > unregisters these. I did check that the naming is ordered right, at least we won't be concurrently creating and destroying umadX sysfs of the same names. I'm also fairly sure we can't be destroying the parent at the same time as this child. Do you see the above commonly? Could it be some driver core thing? Or is it more likely something wrong in umad? Jason