Fix a long-standing TTM issue where we manipulated the vma page_prot
bits while mmap_sem was taken in read mode only. We now make a local
copy of the vma structure which we pass when we set the ptes.
Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 30 +++++++++++++-----------------
1 file changed, 13 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index c03514b..ac617f3 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -102,6 +102,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
int retval = VM_FAULT_NOPAGE;
struct ttm_mem_type_manager *man =
&bdev->man[bo->mem.mem_type];
+ struct vm_area_struct cvma;
/*
* Work around locking order reversal in fault / nopfn
@@ -164,26 +165,21 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
}
/*
- * Strictly, we're not allowed to modify vma->vm_page_prot here,
- * since the mmap_sem is only held in read mode. However, we
- * modify only the caching bits of vma->vm_page_prot and
- * consider those bits protected by
- * the bo->mutex, as we should be the only writers.
- * There shouldn't really be any readers of these bits except
- * within vm_insert_mixed()? fork?
- *
- * TODO: Add a list of vmas to the bo, and change the
- * vma->vm_page_prot when the object changes caching policy, with
- * the correct locks held.
+ * Make a local vma copy to modify the page_prot member
+ * and vm_flags if necessary. The vma parameter is protected
+ * by mmap_sem in write mode.
*/
+ cvma = *vma;
+ cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);
+
if (bo->mem.bus.is_iomem) {
- vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
- vma->vm_page_prot);
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ cvma.vm_page_prot);
} else {
ttm = bo->ttm;
- vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
- vm_get_page_prot(vma->vm_flags) :
- ttm_io_prot(bo->mem.placement, vma->vm_page_prot);
+ if (!(bo->mem.placement & TTM_PL_FLAG_CACHED))
+ cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
+ cvma.vm_page_prot);
/* Allocate all page at once, most common usage */
if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
@@ -210,7 +206,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
pfn = page_to_pfn(page);
}
- ret = vm_insert_mixed(vma, address, pfn);
+ ret = vm_insert_mixed(&cvma, address, pfn);
/*
* Somebody beat us to this PTE or prefaulting to
* an already populated PTE, or prefaulting error.
--
1.7.10.4
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