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[212.51.149.109]) by smtp.gmail.com with ESMTPSA id b9-v6sm9128923edk.62.2018.09.03.00.52.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 03 Sep 2018 00:52:46 -0700 (PDT) Date: Mon, 3 Sep 2018 09:52:44 +0200 From: Daniel Vetter To: Chris Wilson Cc: Jia-Ju Bai , airlied@linux.ie, gustavo@padovan.org, maarten.lankhorst@linux.intel.com, seanpaul@chromium.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Alex Deucher , amd-gfx@lists.freedesktop.org, David Zhou , Christian =?iso-8859-1?Q?K=F6nig?= Subject: Re: [PATCH] gpu: drm: drm_mm: Fix a sleep-in-atomic-context bug in show_leaks() Message-ID: <20180903075244.GE21634@phenom.ffwll.local> Mail-Followup-To: Chris Wilson , Jia-Ju Bai , airlied@linux.ie, gustavo@padovan.org, maarten.lankhorst@linux.intel.com, seanpaul@chromium.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Alex Deucher , amd-gfx@lists.freedesktop.org, David Zhou , Christian =?iso-8859-1?Q?K=F6nig?= References: <20180901122041.2357-1-baijiaju1990@gmail.com> <153580517420.12034.2035309606925619207@skylake-alporthouse-com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <153580517420.12034.2035309606925619207@skylake-alporthouse-com> X-Operating-System: Linux phenom 4.14.0-3-amd64 User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 01, 2018 at 01:32:54PM +0100, Chris Wilson wrote: > Quoting Jia-Ju Bai (2018-09-01 13:20:41) > > The driver may sleep with holding a spinlock. > > > > The function call paths (from bottom to top) in Linux-4.16 are: > > > > [FUNC] kmalloc(GFP_KERNEL) > > drivers/gpu/drm/drm_mm.c, 130: > > kmalloc in show_leaks > > drivers/gpu/drm/drm_mm.c, 913: > > show_leaks in drm_mm_takedown > > drivers/gpu/drm/drm_vma_manager.c, 107: > > drm_mm_takedown in drm_vma_offset_manager_destroy > > drivers/gpu/drm/drm_vma_manager.c, 106: > > _raw_write_lock in drm_vma_offset_manager_destroy > > > > [FUNC] kmalloc(GFP_KERNEL) > > drivers/gpu/drm/drm_mm.c, 130: > > kmalloc in show_leaks > > drivers/gpu/drm/drm_mm.c, 913: > > show_leaks in drm_mm_takedown > > drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 71: > > drm_mm_takedown in amdgpu_vram_mgr_fini > > drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c, 70: > > spin_lock in amdgpu_vram_mgr_fini > > > > [FUNC] kmalloc(GFP_KERNEL) > > drivers/gpu/drm/drm_mm.c, 130: > > kmalloc in show_leaks > > drivers/gpu/drm/drm_mm.c, 913: > > show_leaks in drm_mm_takedown > > drivers/gpu/drm/ttm/ttm_bo_manager.c, 128: > > drm_mm_takedown in ttm_bo_man_takedown > > drivers/gpu/drm/ttm/ttm_bo_manager.c, 126: > > spin_lock in ttm_bo_man_takedown > > > > To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC. > > The bug are above, since those spinlocks do not protect the data and > imply use-after-free. Adding amdgpu, since that's where the bug seems to be. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch