From: Jason Gunthorpe jgg@nvidia.com
[ Upstream commit 0d979509539ed1df883a30d442177ca7be609565 ]
The huge page functionality in TTM does not work safely because PUD and PMD entries do not have a special bit.
get_user_pages_fast() considers any page that passed pmd_huge() as usable:
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) || pmd_devmap(pmd))) {
And vmf_insert_pfn_pmd_prot() unconditionally sets
entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
eg on x86 the page will be _PAGE_PRESENT | PAGE_PSE.
As such gup_huge_pmd() will try to deref a struct page:
head = try_grab_compound_head(pmd_page(orig), refs, flags);
and thus crash.
Thomas further notices that the drivers are not expecting the struct page to be used by anything - in particular the refcount incr above will cause them to malfunction.
Thus everything about this is not able to fully work correctly considering GUP_fast. Delete it entirely. It can return someday along with a proper PMD/PUD_SPECIAL bit in the page table itself to gate GUP_fast.
Fixes: 314b6580adc5 ("drm/ttm, drm/vmwgfx: Support huge TTM pagefaults") Signed-off-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Thomas Hellström thomas.helllstrom@linux.intel.com Reviewed-by: Christian König christian.koenig@amd.com [danvet: Update subject per Thomas' &Christian's review] Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch Link: https://patchwork.freedesktop.org/patch/msgid/0-v2-a44694790652+4ac-ttm_pmd_... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 2 +- drivers/gpu/drm/nouveau/nouveau_gem.c | 2 +- drivers/gpu/drm/radeon/radeon_gem.c | 2 +- drivers/gpu/drm/ttm/ttm_bo_vm.c | 94 +--------------------- drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 4 - drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c | 72 +---------------- drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 3 - include/drm/ttm/ttm_bo_api.h | 3 +- 8 files changed, 7 insertions(+), 175 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c index 9a67746c10edd..b14ff19231b91 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -61,7 +61,7 @@ static vm_fault_t amdgpu_gem_fault(struct vm_fault *vmf) }
ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot, - TTM_BO_VM_NUM_PREFAULT, 1); + TTM_BO_VM_NUM_PREFAULT);
drm_dev_exit(idx); } else { diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c index 8c2ecc2827232..c89d5964148fd 100644 --- a/drivers/gpu/drm/nouveau/nouveau_gem.c +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c @@ -56,7 +56,7 @@ static vm_fault_t nouveau_ttm_fault(struct vm_fault *vmf)
nouveau_bo_del_io_reserve_lru(bo); prot = vm_get_page_prot(vma->vm_flags); - ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1); + ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT); nouveau_bo_add_io_reserve_lru(bo); if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) return ret; diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c index 458f92a708879..a36a4f2c76b09 100644 --- a/drivers/gpu/drm/radeon/radeon_gem.c +++ b/drivers/gpu/drm/radeon/radeon_gem.c @@ -61,7 +61,7 @@ static vm_fault_t radeon_gem_fault(struct vm_fault *vmf) goto unlock_resv;
ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot, - TTM_BO_VM_NUM_PREFAULT, 1); + TTM_BO_VM_NUM_PREFAULT); if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) goto unlock_mclk;
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 5b9b7fd01a692..4a655ab23c89d 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -171,89 +171,6 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo, } EXPORT_SYMBOL(ttm_bo_vm_reserve);
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE -/** - * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults - * @vmf: Fault data - * @bo: The buffer object - * @page_offset: Page offset from bo start - * @fault_page_size: The size of the fault in pages. - * @pgprot: The page protections. - * Does additional checking whether it's possible to insert a PUD or PMD - * pfn and performs the insertion. - * - * Return: VM_FAULT_NOPAGE on successful insertion, VM_FAULT_FALLBACK if - * a huge fault was not possible, or on insertion error. - */ -static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf, - struct ttm_buffer_object *bo, - pgoff_t page_offset, - pgoff_t fault_page_size, - pgprot_t pgprot) -{ - pgoff_t i; - vm_fault_t ret; - unsigned long pfn; - pfn_t pfnt; - struct ttm_tt *ttm = bo->ttm; - bool write = vmf->flags & FAULT_FLAG_WRITE; - - /* Fault should not cross bo boundary. */ - page_offset &= ~(fault_page_size - 1); - if (page_offset + fault_page_size > bo->resource->num_pages) - goto out_fallback; - - if (bo->resource->bus.is_iomem) - pfn = ttm_bo_io_mem_pfn(bo, page_offset); - else - pfn = page_to_pfn(ttm->pages[page_offset]); - - /* pfn must be fault_page_size aligned. */ - if ((pfn & (fault_page_size - 1)) != 0) - goto out_fallback; - - /* Check that memory is contiguous. */ - if (!bo->resource->bus.is_iomem) { - for (i = 1; i < fault_page_size; ++i) { - if (page_to_pfn(ttm->pages[page_offset + i]) != pfn + i) - goto out_fallback; - } - } else if (bo->bdev->funcs->io_mem_pfn) { - for (i = 1; i < fault_page_size; ++i) { - if (ttm_bo_io_mem_pfn(bo, page_offset + i) != pfn + i) - goto out_fallback; - } - } - - pfnt = __pfn_to_pfn_t(pfn, PFN_DEV); - if (fault_page_size == (HPAGE_PMD_SIZE >> PAGE_SHIFT)) - ret = vmf_insert_pfn_pmd_prot(vmf, pfnt, pgprot, write); -#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD - else if (fault_page_size == (HPAGE_PUD_SIZE >> PAGE_SHIFT)) - ret = vmf_insert_pfn_pud_prot(vmf, pfnt, pgprot, write); -#endif - else - WARN_ON_ONCE(ret = VM_FAULT_FALLBACK); - - if (ret != VM_FAULT_NOPAGE) - goto out_fallback; - - return VM_FAULT_NOPAGE; -out_fallback: - count_vm_event(THP_FAULT_FALLBACK); - return VM_FAULT_FALLBACK; -} -#else -static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf, - struct ttm_buffer_object *bo, - pgoff_t page_offset, - pgoff_t fault_page_size, - pgprot_t pgprot) -{ - return VM_FAULT_FALLBACK; -} -#endif - /** * ttm_bo_vm_fault_reserved - TTM fault helper * @vmf: The struct vm_fault given as argument to the fault callback @@ -261,7 +178,6 @@ static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf, * @num_prefault: Maximum number of prefault pages. The caller may want to * specify this based on madvice settings and the size of the GPU object * backed by the memory. - * @fault_page_size: The size of the fault in pages. * * This function inserts one or more page table entries pointing to the * memory backing the buffer object, and then returns a return code @@ -275,8 +191,7 @@ static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf, */ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, pgprot_t prot, - pgoff_t num_prefault, - pgoff_t fault_page_size) + pgoff_t num_prefault) { struct vm_area_struct *vma = vmf->vma; struct ttm_buffer_object *bo = vma->vm_private_data; @@ -327,11 +242,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, prot = pgprot_decrypted(prot); }
- /* We don't prefault on huge faults. Yet. */ - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && fault_page_size != 1) - return ttm_bo_vm_insert_huge(vmf, bo, page_offset, - fault_page_size, prot); - /* * Speculatively prefault a number of pages. Only error on * first page. @@ -429,7 +339,7 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
prot = vma->vm_page_prot; if (drm_dev_enter(ddev, &idx)) { - ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1); + ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT); drm_dev_exit(idx); } else { ret = ttm_bo_vm_dummy_page(vmf, prot); diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h index 5652d982b1ce6..c87d74f0afc52 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h @@ -1526,10 +1526,6 @@ void vmw_bo_dirty_unmap(struct vmw_buffer_object *vbo, pgoff_t start, pgoff_t end); vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf); vm_fault_t vmw_bo_vm_mkwrite(struct vm_fault *vmf); -#ifdef CONFIG_TRANSPARENT_HUGEPAGE -vm_fault_t vmw_bo_vm_huge_fault(struct vm_fault *vmf, - enum page_entry_size pe_size); -#endif
/* Transparent hugepage support - vmwgfx_thp.c */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c index e5a9a5cbd01a7..922317d1acc8a 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c @@ -477,7 +477,7 @@ vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf) else prot = vm_get_page_prot(vma->vm_flags);
- ret = ttm_bo_vm_fault_reserved(vmf, prot, num_prefault, 1); + ret = ttm_bo_vm_fault_reserved(vmf, prot, num_prefault); if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) return ret;
@@ -486,73 +486,3 @@ out_unlock:
return ret; } - -#ifdef CONFIG_TRANSPARENT_HUGEPAGE -vm_fault_t vmw_bo_vm_huge_fault(struct vm_fault *vmf, - enum page_entry_size pe_size) -{ - struct vm_area_struct *vma = vmf->vma; - struct ttm_buffer_object *bo = (struct ttm_buffer_object *) - vma->vm_private_data; - struct vmw_buffer_object *vbo = - container_of(bo, struct vmw_buffer_object, base); - pgprot_t prot; - vm_fault_t ret; - pgoff_t fault_page_size; - bool write = vmf->flags & FAULT_FLAG_WRITE; - - switch (pe_size) { - case PE_SIZE_PMD: - fault_page_size = HPAGE_PMD_SIZE >> PAGE_SHIFT; - break; -#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD - case PE_SIZE_PUD: - fault_page_size = HPAGE_PUD_SIZE >> PAGE_SHIFT; - break; -#endif - default: - WARN_ON_ONCE(1); - return VM_FAULT_FALLBACK; - } - - /* Always do write dirty-tracking and COW on PTE level. */ - if (write && (READ_ONCE(vbo->dirty) || is_cow_mapping(vma->vm_flags))) - return VM_FAULT_FALLBACK; - - ret = ttm_bo_vm_reserve(bo, vmf); - if (ret) - return ret; - - if (vbo->dirty) { - pgoff_t allowed_prefault; - unsigned long page_offset; - - page_offset = vmf->pgoff - - drm_vma_node_start(&bo->base.vma_node); - if (page_offset >= bo->resource->num_pages || - vmw_resources_clean(vbo, page_offset, - page_offset + PAGE_SIZE, - &allowed_prefault)) { - ret = VM_FAULT_SIGBUS; - goto out_unlock; - } - - /* - * Write protect, so we get a new fault on write, and can - * split. - */ - prot = vm_get_page_prot(vma->vm_flags & ~VM_SHARED); - } else { - prot = vm_get_page_prot(vma->vm_flags); - } - - ret = ttm_bo_vm_fault_reserved(vmf, prot, 1, fault_page_size); - if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) - return ret; - -out_unlock: - dma_resv_unlock(bo->base.resv); - - return ret; -} -#endif diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c index e6b1f98ec99f0..0a4c340252ec4 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c @@ -61,9 +61,6 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma) .fault = vmw_bo_vm_fault, .open = ttm_bo_vm_open, .close = ttm_bo_vm_close, -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - .huge_fault = vmw_bo_vm_huge_fault, -#endif }; struct drm_file *file_priv = filp->private_data; struct vmw_private *dev_priv = vmw_priv(file_priv->minor->dev); diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index f681bbdbc6982..36f7eb9d06639 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -594,8 +594,7 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf, pgprot_t prot, - pgoff_t num_prefault, - pgoff_t fault_page_size); + pgoff_t num_prefault);
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf);