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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id j83sm1912436qke.7.2020.05.20.05.48.17 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 May 2020 05:48:18 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jbO8v-00063L-Du; Wed, 20 May 2020 09:48:17 -0300 Date: Wed, 20 May 2020 09:48:17 -0300 From: Jason Gunthorpe To: Michel Lespinasse Cc: John Hubbard , Matthew Wilcox , Laurent Dufour , Andrew Morton , linux-mm , LKML , Peter Zijlstra , Vlastimil Babka , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Daniel Jordan Subject: Re: [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock Message-ID: <20200520124817.GG31189@ziepe.ca> References: <20200423015917.GA13910@bombadil.infradead.org> <20200424012612.GA158937@google.com> <20200424013958.GC158937@google.com> <20200519131009.GD189720@google.com> <7c540ac9-ba44-7187-5dc2-60b4c761e91c@linux.ibm.com> <20200519153251.GY16070@bombadil.infradead.org> <10d48b77-5c6e-2e10-84e6-16cdd76a45f1@nvidia.com> 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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 19, 2020 at 07:39:30PM -0700, Michel Lespinasse wrote: > > > I think this assertion should be deleted from this driver. It's there > > > in case get_user_pages_fast() takes the mmap sem. It would make sense to > > > have this assertion in get_user_pages_fast() in case we take the fast path > > > which doesn't acquire the mmap_sem. Something like this: > > I like this idea a lot - having might_lock assertions in > get_user_pages_fast makes a log more sense than doing the same at the > call sites. +1 I've wanted to see more complete lockdep annotations in gup.c for a while now.. There has been a number of bugs this would have caught Jason