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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id z57sm9460981qta.62.2019.06.17.17.45.09 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 17 Jun 2019 17:45:09 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hd2FJ-0000ob-FF; Mon, 17 Jun 2019 21:45:09 -0300 Date: Mon, 17 Jun 2019 21:45:09 -0300 From: Jason Gunthorpe To: Christoph Hellwig Cc: Jerome Glisse , Ralph Campbell , John Hubbard , Felix.Kuehling@amd.com, linux-rdma@vger.kernel.org, linux-mm@kvack.org, Andrea Arcangeli , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Ben Skeggs , Philip Yang Subject: Re: [PATCH v3 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release Message-ID: <20190618004509.GE30762@ziepe.ca> References: <20190614004450.20252-1-jgg@ziepe.ca> <20190614004450.20252-12-jgg@ziepe.ca> <20190615142106.GK17724@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190615142106.GK17724@infradead.org> User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Jun 15, 2019 at 07:21:06AM -0700, Christoph Hellwig wrote: > On Thu, Jun 13, 2019 at 09:44:49PM -0300, Jason Gunthorpe wrote: > > From: Jason Gunthorpe > > > > hmm_release() is called exactly once per hmm. ops->release() cannot > > accidentally trigger any action that would recurse back onto > > hmm->mirrors_sem. > > In linux-next amdgpu actually calls hmm_mirror_unregister from its > release function. That whole release function looks rather sketchy, > but we probably need to sort that out first. Does it? I see this: static void amdgpu_hmm_mirror_release(struct hmm_mirror *mirror) { struct amdgpu_mn *amn = container_of(mirror, struct amdgpu_mn, mirror); INIT_WORK(&amn->work, amdgpu_mn_destroy); schedule_work(&amn->work); } static struct hmm_mirror_ops amdgpu_hmm_mirror_ops[] = { [AMDGPU_MN_TYPE_GFX] = { .sync_cpu_device_pagetables = amdgpu_mn_sync_pagetables_gfx, .release = amdgpu_hmm_mirror_release }, [AMDGPU_MN_TYPE_HSA] = { .sync_cpu_device_pagetables = amdgpu_mn_sync_pagetables_hsa, .release = amdgpu_hmm_mirror_release }, }; Am I looking at the wrong thing? Looks like it calls it through a work queue should should be OK.. Though very strange that amdgpu only destroys the mirror via release, that cannot be right. Jason