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([2a02:908:1252:fb60:be8a:bd56:1f94:86e7]) by smtp.gmail.com with ESMTPSA id b18sm5628976ejc.41.2020.07.30.05.03.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jul 2020 05:03:11 -0700 (PDT) Reply-To: christian.koenig@amd.com Subject: Re: [Linaro-mm-sig] [PATCH] dma-resv: lockdep-prime address_space->i_mmap_rwsem for dma-resv To: Daniel Vetter , DRI Development Cc: linux-xfs@vger.kernel.org, Maarten Lankhorst , linux-rdma@vger.kernel.org, Intel Graphics Development , Dave Chinner , =?UTF-8?Q?Christian_K=c3=b6nig?= , linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, Jason Gunthorpe , Qian Cai , linux-fsdevel@vger.kernel.org, Daniel Vetter , Andrew Morton , linux-media@vger.kernel.org References: <20200728135839.1035515-1-daniel.vetter@ffwll.ch> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: Date: Thu, 30 Jul 2020 14:03:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200728135839.1035515-1-daniel.vetter@ffwll.ch> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Am 28.07.20 um 15:58 schrieb Daniel Vetter: > GPU drivers need this in their shrinkers, to be able to throw out > mmap'ed buffers. Note that we also need dma_resv_lock in shrinkers, > but that loop is resolved by trylocking in shrinkers. > > So full hierarchy is now (ignore some of the other branches we already > have primed): > > mmap_read_lock -> dma_resv -> shrinkers -> i_mmap_lock_write > > I hope that's not inconsistent with anything mm or fs does, adding > relevant people. > > Signed-off-by: Daniel Vetter > Cc: Sumit Semwal > Cc: "Christian König" > Cc: linux-media@vger.kernel.org > Cc: linaro-mm-sig@lists.linaro.org > Cc: Dave Chinner > Cc: Qian Cai > Cc: linux-xfs@vger.kernel.org > Cc: linux-fsdevel@vger.kernel.org > Cc: Thomas Hellström (Intel) > Cc: Andrew Morton > Cc: Jason Gunthorpe > Cc: linux-mm@kvack.org > Cc: linux-rdma@vger.kernel.org > Cc: Maarten Lankhorst Reviewed-by: Christian König > --- > drivers/dma-buf/dma-resv.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c > index 0e6675ec1d11..9678162a4ac5 100644 > --- a/drivers/dma-buf/dma-resv.c > +++ b/drivers/dma-buf/dma-resv.c > @@ -104,12 +104,14 @@ static int __init dma_resv_lockdep(void) > struct mm_struct *mm = mm_alloc(); > struct ww_acquire_ctx ctx; > struct dma_resv obj; > + struct address_space mapping; > int ret; > > if (!mm) > return -ENOMEM; > > dma_resv_init(&obj); > + address_space_init_once(&mapping); > > mmap_read_lock(mm); > ww_acquire_init(&ctx, &reservation_ww_class); > @@ -117,6 +119,9 @@ static int __init dma_resv_lockdep(void) > if (ret == -EDEADLK) > dma_resv_lock_slow(&obj, &ctx); > fs_reclaim_acquire(GFP_KERNEL); > + /* for unmap_mapping_range on trylocked buffer objects in shrinkers */ > + i_mmap_lock_write(&mapping); > + i_mmap_unlock_write(&mapping); > #ifdef CONFIG_MMU_NOTIFIER > lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); > __dma_fence_might_wait();