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[157.230.128.187]) by smtp.gmail.com with ESMTPSA id a18sm12089121pjh.25.2020.04.19.16.07.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Apr 2020 16:07:31 -0700 (PDT) Received: by 42.do-not-panic.com (Postfix, from userid 1000) id CBDD3403EA; Sun, 19 Apr 2020 23:07:30 +0000 (UTC) Date: Sun, 19 Apr 2020 23:07:30 +0000 From: Luis Chamberlain To: Bart Van Assche Cc: axboe@kernel.dk, viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org, rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com, nstange@suse.de, akpm@linux-foundation.org, mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 05/10] blktrace: upgrade warns to BUG_ON() on unexpected circmunstances Message-ID: <20200419230730.GH11244@42.do-not-panic.com> References: <20200419194529.4872-1-mcgrof@kernel.org> <20200419194529.4872-6-mcgrof@kernel.org> <54b63fd9-0c73-5fdc-b43d-6ab4aec3a00d@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54b63fd9-0c73-5fdc-b43d-6ab4aec3a00d@acm.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000364, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Apr 19, 2020 at 03:50:13PM -0700, Bart Van Assche wrote: > On 4/19/20 12:45 PM, Luis Chamberlain wrote: > > @@ -498,10 +498,7 @@ static struct dentry *blk_trace_debugfs_dir(struct blk_user_trace_setup *buts, > > struct dentry *dir = NULL; > > /* This can only happen if we have a bug on our lower layers */ > > - if (!q->kobj.parent) { > > - pr_warn("%s: request_queue parent is gone\n", buts->name); > > - return NULL; > > - } > > + BUG_ON(!q->kobj.parent); > > Does the following quote from Linus also apply to this patch: "there is NO > F*CKING EXCUSE to knowingly kill the kernel." See also > https://lkml.org/lkml/2016/10/4/1. We can use WARN_ON() and keep the return NULL, sure. Luis