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[91.14.161.181]) by smtp.gmail.com with ESMTPSA id v28sm17238559wrv.93.2021.08.30.23.19.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Aug 2021 23:19:02 -0700 (PDT) Subject: Re: [PATCH] drm/amdgpu: Fix a deadlock if previous GEM object allocation fails To: "Pan, Xinhui" , "Grodzovsky, Andrey" , "amd-gfx@lists.freedesktop.org" Cc: "Koenig, Christian" , "Deucher, Alexander" References: <0a52e64c-c5c7-ab65-4370-94374e2d0458@amd.com> <9AE27401-DFDB-44C1-86BE-064F3378D5D5@amd.com> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: <72e03423-461c-c6c9-e1f4-84d185cf3ab4@gmail.com> Date: Tue, 31 Aug 2021 08:19:01 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <9AE27401-DFDB-44C1-86BE-064F3378D5D5@amd.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" Am 31.08.21 um 07:47 schrieb Pan, Xinhui: > > 在 2021/8/31 13:38，“Pan, Xinhui” 写入: > > > > 在 2021/8/31 12:03，“Grodzovsky, Andrey” 写入: > > > On 2021-08-30 11:24 p.m., Pan, Xinhui wrote: > > [AMD Official Use Only] > > > > [AMD Official Use Only] > > > > Unreserve root BO before return otherwise next allocation got deadlock. > > > > Signed-off-by: xinhui pan > > --- > > drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 11 +++++------ > > 1 file changed, 5 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c > > index 85b292ed5c43..c9db7d2c5816 100644 > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c > > @@ -355,19 +355,18 @@ int amdgpu_gem_create_ioctl(struct drm_device *dev, void *data, > > DRM_DEBUG("Failed to allocate GEM object (%llu, %d, %llu, %d)\n", > > size, initial_domain, args->in.alignment, r); > > } > > + > > + if (flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID) > > + amdgpu_bo_unreserve(vm->root.bo); > > return r; > > } > > > > if (flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID) { > > - if (!r) { > > - struct amdgpu_bo *abo = gem_to_amdgpu_bo(gobj); > > + struct amdgpu_bo *abo = gem_to_amdgpu_bo(gobj); > > > > - abo->parent = amdgpu_bo_ref(vm->root.bo); > > - } > > + abo->parent = amdgpu_bo_ref(vm->root.bo); > > amdgpu_bo_unreserve(vm->root.bo); > > } > > - if (r) > > - return r; > > > The above early return seems to be needed for -ERESTARTSYS case. > > Andrey > > There are two returns. ERESTARTSYS and other error after retry are already handled by the first return in if {}. So the second return is not needed. > > Thanks > Xinhui > > Also we can do something like below which is simpler. Yeah, I think that would be better. We could also change the "if (r) { if (r != -ERESTARTSYS) {" into just "if (r != -ERESTARTSYS)" then. But good catch anyway. Regards, Christian. > @@ -355,7 +355,6 @@ int amdgpu_gem_create_ioctl(struct drm_device *dev, void *data, > DRM_DEBUG("Failed to allocate GEM object (%llu, %d, %llu, %d)\n", > size, initial_domain, args->in.alignment, r); > } > - return r; > } > > if (flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID) { > > > > > > r = drm_gem_handle_create(filp, gobj, &handle); > > /* drop reference from allocate - handle holds it now */ > > -- > > 2.25.1 > > > >