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Mon, 12 Oct 2020 01:52:06 -0700 (PDT) Received: from abel.fritz.box ([2a02:908:1252:fb60:6a6c:c67:2644:1d74]) by smtp.gmail.com with ESMTPSA id o35sm8622988edd.4.2020.10.12.01.52.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Oct 2020 01:52:06 -0700 (PDT) From: " =?utf-8?q?Christian_K=C3=B6nig?= " X-Google-Original-From: =?utf-8?q?Christian_K=C3=B6nig?= To: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, chris@chris-wilson.co.uk, airlied@redhat.com, daniel@ffwll.ch, sumit.semwal@linaro.org, willy@infradead.org, jhubbard@nvidia.com, jgg@ziepe.ca, linmiaohe@huawei.com Subject: [PATCH 2/2] mm: introduce vma_set_file function v4 Date: Mon, 12 Oct 2020 10:52:03 +0200 Message-Id: <20201012085203.56119-2-christian.koenig@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201012085203.56119-1-christian.koenig@amd.com> References: <20201012085203.56119-1-christian.koenig@amd.com> MIME-Version: 1.0 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: Add the new vma_set_file() function to allow changing vma->vm_file with the necessary refcount dance. v2: add more users of this. v3: add missing EXPORT_SYMBOL, rebase on mmap cleanup, add comments why we drop the reference on two occasions. v4: make it clear that changing an anonymous vma is illegal. Signed-off-by: Christian König Reviewed-by: Daniel Vetter (v2) Reported-by: kernel test robot Reported-by: kernel test robot Reported-by: kernel test robot Reviewed-by: Jason Gunthorpe --- drivers/dma-buf/dma-buf.c | 3 +-- drivers/gpu/drm/etnaviv/etnaviv_gem.c | 4 +--- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 3 +-- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 5 +++-- drivers/gpu/drm/msm/msm_gem.c | 4 +--- drivers/gpu/drm/omapdrm/omap_gem.c | 3 +-- drivers/gpu/drm/vgem/vgem_drv.c | 3 +-- drivers/staging/android/ashmem.c | 6 +++--- include/linux/mm.h | 2 ++ mm/mmap.c | 12 ++++++++++++ 10 files changed, 26 insertions(+), 19 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 08630d057cf2..8e6a114c6034 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1160,8 +1160,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, return -EINVAL; /* readjust the vma */ - fput(vma->vm_file); - vma->vm_file = get_file(dmabuf->file); + vma_set_file(vma, dmabuf->file); vma->vm_pgoff = pgoff; return dmabuf->ops->mmap(dmabuf, vma); diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c index 312e9d58d5a7..10ce267c0947 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c @@ -145,10 +145,8 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_gem_object *etnaviv_obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); - get_file(etnaviv_obj->base.filp); vma->vm_pgoff = 0; - vma->vm_file = etnaviv_obj->base.filp; + vma_set_file(vma, etnaviv_obj->base.filp); vma->vm_page_prot = vm_page_prot; } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index fec0e1e3dc3e..8ce4c9e28b87 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -119,8 +119,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct * if (ret) return ret; - fput(vma->vm_file); - vma->vm_file = get_file(obj->base.filp); + vma_set_file(vma, obj->base.filp); return 0; } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 3d69e51f3e4d..ec28a6cde49b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -893,8 +893,9 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma) * requires avoiding extraneous references to their filp, hence why * we prefer to use an anonymous file for their mmaps. */ - fput(vma->vm_file); - vma->vm_file = anon; + vma_set_file(vma, anon); + /* Drop the initial creation reference, the vma is now holding one. */ + fput(anon); switch (mmo->mmap_type) { case I915_MMAP_TYPE_WC: diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index de915ff6f4b4..a71f42870d5e 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -223,10 +223,8 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); - get_file(obj->filp); vma->vm_pgoff = 0; - vma->vm_file = obj->filp; + vma_set_file(vma, obj->filp); vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); } diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c index 979d53a93c2b..0d4542ff1d7d 100644 --- a/drivers/gpu/drm/omapdrm/omap_gem.c +++ b/drivers/gpu/drm/omapdrm/omap_gem.c @@ -564,9 +564,8 @@ int omap_gem_mmap_obj(struct drm_gem_object *obj, * address_space (so unmap_mapping_range does what we want, * in particular in the case of mmap'd dmabufs) */ - fput(vma->vm_file); vma->vm_pgoff = 0; - vma->vm_file = get_file(obj->filp); + vma_set_file(vma, obj->filp); vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); } diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index fa54a6d1403d..ea0eecae5153 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -397,8 +397,7 @@ static int vgem_prime_mmap(struct drm_gem_object *obj, if (ret) return ret; - fput(vma->vm_file); - vma->vm_file = get_file(obj->filp); + vma_set_file(vma, obj->filp); vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags)); diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index 10b4be1f3e78..4789d36ddfd3 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -450,9 +450,9 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) vma_set_anonymous(vma); } - if (vma->vm_file) - fput(vma->vm_file); - vma->vm_file = asma->file; + vma_set_file(vma, asma->file); + /* XXX: merge this with the get_file() above if possible */ + fput(asma->file); out: mutex_unlock(&ashmem_mutex); diff --git a/include/linux/mm.h b/include/linux/mm.h index ca6e6a81576b..f7a005153d02 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2693,6 +2693,8 @@ static inline void vma_set_page_prot(struct vm_area_struct *vma) } #endif +void vma_set_file(struct vm_area_struct *vma, struct file *file); + #ifdef CONFIG_NUMA_BALANCING unsigned long change_prot_numa(struct vm_area_struct *vma, unsigned long start, unsigned long end); diff --git a/mm/mmap.c b/mm/mmap.c index 3a2670d73355..8634d0bb54ad 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -136,6 +136,18 @@ void vma_set_page_prot(struct vm_area_struct *vma) WRITE_ONCE(vma->vm_page_prot, vm_page_prot); } +/* + * Change backing file, only valid to use during initial VMA setup. + */ +void vma_set_file(struct vm_area_struct *vma, struct file *file) +{ + /* Changing an anonymous vma with this is illegal */ + get_file(file); + swap(vma->vm_file, file); + fput(file); +} +EXPORT_SYMBOL(vma_set_file); + /* * Requires inode->i_mapping->i_mmap_rwsem */