summaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
authorJason Gunthorpe <jgg@nvidia.com>2021-10-20 01:27:31 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2021-11-05 11:13:19 +0100
commit0d979509539ed1df883a30d442177ca7be609565 (patch)
tree783afaf2a055723bcb4dd927c445eeb1b201a6e6 /include
parentdma-buf/poll: Get a file reference for outstanding fence callbacks (diff)
downloadlinux-0d979509539ed1df883a30d442177ca7be609565.tar.xz
linux-0d979509539ed1df883a30d442177ca7be609565.zip
drm/ttm: remove ttm_bo_vm_insert_huge()
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_jgg@nvidia.com
Diffstat (limited to 'include')
-rw-r--r--include/drm/ttm/ttm_bo_api.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 0551e2587f14..cd785cfa3123 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -584,8 +584,7 @@ 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);