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[192.55.52.120]) by mx.google.com with ESMTPS id s68si3116938pfb.39.2019.06.07.15.32.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Jun 2019 15:32:12 -0700 (PDT) Received-SPF: pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.120 as permitted sender) client-ip=192.55.52.120; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ira.weiny@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=ira.weiny@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Jun 2019 15:32:11 -0700 X-ExtLoop1: 1 Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga008.jf.intel.com with ESMTP; 07 Jun 2019 15:32:10 -0700 Date: Fri, 7 Jun 2019 15:33:24 -0700 From: Ira Weiny To: Jason Gunthorpe 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, Jason Gunthorpe Subject: Re: [PATCH v2 hmm 02/11] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Message-ID: <20190607223324.GD14559@iweiny-DESK2.sc.intel.com> References: <20190606184438.31646-1-jgg@ziepe.ca> <20190606184438.31646-3-jgg@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190606184438.31646-3-jgg@ziepe.ca> User-Agent: Mutt/1.11.1 (2018-12-01) 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 Thu, Jun 06, 2019 at 03:44:29PM -0300, 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; I don't think you need this assignment here. In the code below (right after the mutext_lock()) it is set already. And looks like it remains that way after the end of the series. Reviewed-by: Ira Weiny > + kref_get(&hmm->kref); > > /* Initialize range to track CPU page table updates. */ > mutex_lock(&hmm->lock); > -- > 2.21.0 >