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[216.228.121.64]) by mx.google.com with ESMTPS id z186si575488oiz.28.2019.06.06.19.36.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 19:36:18 -0700 (PDT) Received-SPF: pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.64 as permitted sender) client-ip=216.228.121.64; Authentication-Results: mx.google.com; dkim=pass header.i=@nvidia.com header.s=n1 header.b=Al0TXJZB; spf=pass (google.com: domain of jhubbard@nvidia.com designates 216.228.121.64 as permitted sender) smtp.mailfrom=jhubbard@nvidia.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=nvidia.com Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 06 Jun 2019 19:36:03 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Thu, 06 Jun 2019 19:36:17 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Thu, 06 Jun 2019 19:36:17 -0700 Received: from [10.110.48.28] (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 7 Jun 2019 02:36:16 +0000 Subject: Re: [PATCH v2 hmm 02/11] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register To: Jason Gunthorpe , Jerome Glisse , "Ralph Campbell" , CC: , , Andrea Arcangeli , , , Jason Gunthorpe References: <20190606184438.31646-1-jgg@ziepe.ca> <20190606184438.31646-3-jgg@ziepe.ca> X-Nvconfidentiality: public From: John Hubbard Message-ID: <7902a4fa-f789-de3f-e448-a8cfc412f40b@nvidia.com> Date: Thu, 6 Jun 2019 19:36:15 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190606184438.31646-3-jgg@ziepe.ca> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1559874963; bh=VS+EJuXcHOl/Y4VTDcHn1QB4ZCx6paXXC66trO1FQ50=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=Al0TXJZBwEkVZOZLD+8oC+fGR+4awq+psveUro+gmkBw0ex9RNhYyL2afTzYC14Gr 8zB5XgAXfiKt5Ff+657AS8ZHpALXU0H/KUEvYt9Mi7EarnemI51LhZ5vBL29ckj1zd HP+FGiZDyljWrHzzDBl3Uzj3nlWpgR9gxtx1fChJdV8n1uEp+pOMmXcSI4THVyOuz4 n6AOMfvn4cvrqQMM4O9BBxmDqcFBYuAjgDD0zIF/AKUB6D3WrX7nk49LFB2nZf5tzU 4H43m7RivZWoi8z1XfLcHDx2C0oWYchI7sQt2wgJByok8/0FGFOqi+QL4QrsnjcO0+ EOVIBu40QOceA== 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 6/6/19 11:44 AM, Jason Gunthorpe wrote: > From: Jason Gunthorpe > > Ralph observes that hmm_range_register() can only be called by a driver > while a mirror is registered. Make this clear in the API by passing in the > mirror structure as a parameter. > > This also simplifies understanding the lifetime model for struct hmm, as > the hmm pointer must be valid as part of a registered mirror so all we > need in hmm_register_range() is a simple kref_get. > > Suggested-by: Ralph Campbell > Signed-off-by: Jason Gunthorpe > --- > v2 > - Include the oneline patch to nouveau_svm.c > --- > drivers/gpu/drm/nouveau/nouveau_svm.c | 2 +- > include/linux/hmm.h | 7 ++++--- > mm/hmm.c | 15 ++++++--------- > 3 files changed, 11 insertions(+), 13 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c > index 93ed43c413f0bb..8c92374afcf227 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_svm.c > +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c > @@ -649,7 +649,7 @@ nouveau_svm_fault(struct nvif_notify *notify) > range.values = nouveau_svm_pfn_values; > range.pfn_shift = NVIF_VMM_PFNMAP_V0_ADDR_SHIFT; > again: > - ret = hmm_vma_fault(&range, true); > + ret = hmm_vma_fault(&svmm->mirror, &range, true); > if (ret == 0) { > mutex_lock(&svmm->mutex); > if (!hmm_vma_range_done(&range)) { > diff --git a/include/linux/hmm.h b/include/linux/hmm.h > index 688c5ca7068795..2d519797cb134a 100644 > --- a/include/linux/hmm.h > +++ b/include/linux/hmm.h > @@ -505,7 +505,7 @@ static inline bool hmm_mirror_mm_is_alive(struct hmm_mirror *mirror) > * Please see Documentation/vm/hmm.rst for how to use the range API. > */ > int hmm_range_register(struct hmm_range *range, > - struct mm_struct *mm, > + struct hmm_mirror *mirror, > unsigned long start, > unsigned long end, > unsigned page_shift); > @@ -541,7 +541,8 @@ static inline bool hmm_vma_range_done(struct hmm_range *range) > } > > /* This is a temporary helper to avoid merge conflict between trees. */ > -static inline int hmm_vma_fault(struct hmm_range *range, bool block) > +static inline int hmm_vma_fault(struct hmm_mirror *mirror, > + struct hmm_range *range, bool block) > { > long ret; > > @@ -554,7 +555,7 @@ static inline int hmm_vma_fault(struct hmm_range *range, bool block) > range->default_flags = 0; > range->pfn_flags_mask = -1UL; > > - ret = hmm_range_register(range, range->vma->vm_mm, > + ret = hmm_range_register(range, mirror, > range->start, range->end, > PAGE_SHIFT); > if (ret) > diff --git a/mm/hmm.c b/mm/hmm.c > index 547002f56a163d..8796447299023c 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -925,13 +925,13 @@ static void hmm_pfns_clear(struct hmm_range *range, > * Track updates to the CPU page table see include/linux/hmm.h > */ > int hmm_range_register(struct hmm_range *range, > - struct mm_struct *mm, > + struct hmm_mirror *mirror, > unsigned long start, > unsigned long end, > unsigned page_shift) > { > unsigned long mask = ((1UL << page_shift) - 1UL); > - struct hmm *hmm; > + struct hmm *hmm = mirror->hmm; > > range->valid = false; > range->hmm = NULL; > @@ -945,15 +945,12 @@ int hmm_range_register(struct hmm_range *range, > range->start = start; > range->end = end; > > - hmm = hmm_get_or_create(mm); > - if (!hmm) > - return -EFAULT; > - > /* Check if hmm_mm_destroy() was call. */ > - if (hmm->mm == NULL || hmm->dead) { > - hmm_put(hmm); > + if (hmm->mm == NULL || hmm->dead) > return -EFAULT; > - } > + > + range->hmm = hmm; > + kref_get(&hmm->kref); > > /* Initialize range to track CPU page table updates. */ > mutex_lock(&hmm->lock); > I'm not a qualified Nouveau reviewer, but this looks obviously correct, so: Reviewed-by: John Hubbard thanks, -- John Hubbard NVIDIA