Commit c445c166 authored by Thomas Hellstrom (VMware)'s avatar Thomas Hellstrom (VMware) Committed by Dave Airlie
Browse files

drm/ttm: Temporarily disable the huge_fault() callback 



With amdgpu and CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y, there are
errors like:
BUG: non-zero pgtables_bytes on freeing mm
and:
BUG: Bad rss-counter state
with TTM transparent huge-pages.
Until we've figured out what other TTM drivers do differently compared to
vmwgfx, disable the huge_fault() callback, eliminating transhuge
page-table entries.

Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: default avatarThomas Hellstrom (VMware) <thomas_os@shipmail.org>
Reported-by: default avatarAlex Xu (Hello71) <alex_y_xu@yahoo.ca>
Tested-by: default avatarAlex Xu (Hello71) <alex_y_xu@yahoo.ca>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200409164925.11912-1-thomas_os@shipmail.org
parent cb6d4066

drivers/gpu/drm/ttm/ttm_bo_vm.c

+0 −63
Original line number Diff line number Diff line
@@ -436,66 +436,6 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf) 
}

EXPORT_SYMBOL(ttm_bo_vm_fault);



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

/**

 * ttm_pgprot_is_wrprotecting - Is a page protection value write-protecting?

 * @prot: The page protection value

 *

 * Return: true if @prot is write-protecting. false otherwise.

 */

static bool ttm_pgprot_is_wrprotecting(pgprot_t prot)

{

	/*

	 * This is meant to say "pgprot_wrprotect(prot) == prot" in a generic

	 * way. Unfortunately there is no generic pgprot_wrprotect.

	 */

	return pte_val(pte_wrprotect(__pte(pgprot_val(prot)))) ==

		pgprot_val(prot);

}



static vm_fault_t ttm_bo_vm_huge_fault(struct vm_fault *vmf,

				       enum page_entry_size pe_size)

{

	struct vm_area_struct *vma = vmf->vma;

	pgprot_t prot;

	struct ttm_buffer_object *bo = vma->vm_private_data;

	vm_fault_t ret;

	pgoff_t fault_page_size = 0;

	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;

	}



	/* Fallback on write dirty-tracking or COW */

	if (write && ttm_pgprot_is_wrprotecting(vma->vm_page_prot))

		return VM_FAULT_FALLBACK;



	ret = ttm_bo_vm_reserve(bo, vmf);

	if (ret)

		return ret;



	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;



	dma_resv_unlock(bo->base.resv);



	return ret;

}

#endif



void ttm_bo_vm_open(struct vm_area_struct *vma)

{

	struct ttm_buffer_object *bo = vma->vm_private_data;
@@ -598,9 +538,6 @@ static const struct vm_operations_struct ttm_bo_vm_ops = { 
	.open = ttm_bo_vm_open,

	.close = ttm_bo_vm_close,

	.access = ttm_bo_vm_access,

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	.huge_fault = ttm_bo_vm_huge_fault,

#endif

};



static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,

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